In April 1986, the Chernobyl nuclear power station in Ukraine had a deadly and costly experiment that led to the greatest nuclear accident on record, killing 32 people instantly and crippling thousands more in Russia, France and Italy.
The explosion, which resulted from an unstable nuclear reactor getting overheated, poisoned the wildlife and led to an exponential rise in cancer cases in the surrounding area.

The Worst Nuclear Accident

On 30 April 1986, the world’s worst nuclear disaster goes public, days after the event. What exactly happened at Reactor Number Four at Chernobyl's nuclear power plant, and why?

Stashed ideas

Published: <time datetime="2021-07-21T08:30:48+01:00" dir="ltr">July 21, 2021 at 8:30 am </time>

When an ill-conceived experiment at Chernobyl nuclear power station went wrong on 26 April 1986, the consequences were catastrophic.

Technicians on Reactor Number Four at the Soviet plant, in Ukraine, hoped to ascertain whether the reactor turbine could power the cooling pumps, in case of electrical failure. They did this by running the reactor on low power but disabling emergency safety systems – including the automatic shutdown.

The increasingly unstable reactor overheated but tests weren’t cancelled, regulations were ignored and mistakes piled up until 1.23am, when a chain reaction in the core caused a power surge and meltdown. The reactor exploded, sending flames and radioactive material 300 metres into the sky.

What followed was a tragic and costly cover-up. Firefighters weren’t informed of the radiation, so were exposed to fatal doses, while the evacuation of the nearby city of Pripyat didn’t begin for 36 hours. It was only after monitoring stations in Sweden (620 miles away) picked up high radioactivity in the air that the accident was made public on Russian news.

The radiation was contained by early May, but at extreme risk to the workers who built a concrete-and-steel ‘sarcophagus’ over the reactor.

In the immediate aftermath, 32 people perished due to radioactivity, but countless more died later as radiation blew as far as Russia, France and Italy.

An ‘exclusion zone’ extended nearly 19 miles from the station, but that couldn’t stop the poisoning of wildlife, a drastic rise in cancer cases and worldwide fear that nuclear power was far from safe.

Jonny Wilkes is a freelance writer specialising in history

What was the Chernobyl Disaster?

In the 19th Century, manufacturers added all kinds of unpleasant substances to processed food.
Milk sellers in the US once added chalk or dye to make their watered-down batches look more palatable. Other food companies added copper sulphate - a garden pesticide - to their tinned vegetables to make them look greener. Formaldehyde or borax was added to extend shelf life. In England, green sugary sweets were coloured with arsenic, and lead was added to red or yellow ones.

The need for food labelling

Health

Forcing stricter labelling regulations took decades. Today, processed foods come with abundant information about their contents, although it is not always easy to understand. Food regulations differ around the world. The UN and WHO's Codex Alimentarius provides an international set of labelling standards, but the food code is voluntary and used in different ways worldwide. Nutrition labelling is mandatory in the major economies, including the US, India, China, Japan, Australia and EU members.

Food regulations around the world

The ingredients are listed from the main ingredient to the least ingredient by weight. For hazelnut spread, the first (and biggest) ingredient is sugar, then oil. <ul><li>Lower down, you'll come across "E numbers". The EU uses these shortcodes to describe additives. For example, E300 is vitamin C, E160c is paprika.</li><li>In the US, there is no such coding. Instead, additives are described by their chemical names, such as sodium caseinate rather than E469. But it really refers to a protein derived from milk.</li></ul>

Understanding ingredients

Some nations like the UK use red, amber, and green colour codes to express how healthy a processed food is in terms of fat, saturates, sugars and salt.  For example, a processed meal might have 7.7g of saturated fat and be labelled red. It may also show a percentage like 39%. The amount is calculated using the "Reference intake", which is the maximum recommended intake amount for an adult woman who does an average amount of physical activity.

Nutrition facts

Serving size was another definition that may seem obvious at first but is complex to define. Until the Nutrition Facts label appeared, each manufacturer decided for themselves how big a portion was. <ul><li>The 1990 US legislation mandated that the serving size should be the amount "customarily consumed and which is expressed in a common household measure that is appropriate to the food"—but knowing what a serving size is required national surveys. </li><li>In the end, the FDA calculated the US serving sizes by using 139 categories, which includes four types of cereal and four types of cheese.</li></ul>

Serving sizes

Health claims are regulated to avoid manufacturers over-promising.  The US uses three relevant types of claims:<ul><li>Authorised claim: The approved claim must have "significant scientific agreement."</li><li>Qualified claim: The science is not settled. "Scientific evidence suggests..."</li><li>Structure-function claim: These claims are vague, such as "calcium builds strong bones". They should be viewed as marketing language.</li></ul>

Health and nutrition claims

The information on a processed food label may seem obvious, but there's often more to decipher than first appears.

To begin, it's worth acknowledging that food regulations differ around the world, so it would require more than a single article to describe every country's labelling conventions. The UN and WHO's <a dir="ltr" href="http://www.fao.org/fao-who-codexalimentarius/en/">Codex Alimentarius </a>provides an international set of labelling standards, but this "food code" is voluntary, and is applied in different ways around the world. When it comes to <a dir="ltr" href="http://www.eufic.org/images/uploads/files/ExecutiveSummary.pdf">nutrition labelling </a>, most of the world's major economies make it mandatory, including the US, India, China, Japan, Australia and EU members. But for some it is voluntary unless a health claim is made, such as in Turkey, Singapore or South Africa.

Generally though, most labels feature an ingredient list and some information about the product's nutritional value: calories, fat, sugars, salt and so on. In recent decades, manufacturers have also started adding health and wellbeing benefits, aware that it helps sell their products.

All clear and obvious? Not quite.

Understanding ingredients

For starters, consider the ingredient list . What manufacturers don't spell out on the front is that these are listed from most predominant to least predominant by weight. So far, so obvious, you might say. But it does lead to some labelling sleight of hand. For instance, if you look closer at a hazelnut spread label, past the pictures of nuts on the front, you'll notice that the first (and therefore biggest) ingredient is actually sugar, often followed by oil. You can find a similar pattern with breakfast cereal: even if a box advertises "wholegrain wheat" in big letters on the front, the ingredients often list sugar in a close second place. Some brands of frosted flakes, for example, have <a dir="ltr" href="https://theconversation.com/how-much-sugar-is-lurking-in-your-cereal-36797">37g of sugar for every 100g of cereal </a>. That's roughly the same ratio as in a chocolate chip cookie.

A few, like the artificial colour E122 in cakes and sweets, may have adverse effects on children prone to hyperactivity

Lower down the ingredient list, you'll also come across names that are less recognisable than oats, sugar or nuts. In the EU, manufacturers use a system of <a dir="ltr" href="https://webgate.ec.europa.eu/foods_system/main/?sector=FAD&amp;auth=SANCAS">short codes to describe additives called "E numbers" </a>, which over the years have acquired a controversial – and occasionally undeserved – reputation as dangerous and mysterious chemicals. A few, like the artificial colour E122 in cakes and sweets, may have <a dir="ltr" href="https://www.food.gov.uk/safety-hygiene/food-additives#food-colours-and-hyperactivity">adverse effects on children </a>prone to hyperactivity. But others are good for you, or at least harmless: <a dir="ltr" href="https://www.bbc.co.uk/blogs/food/2010/08/are-e-numbers-really-bad-for-y.shtml">E300 is vitamin C, E948 is oxygen and E160c is paprika. </a>

In the US, there is no such coding, and such additives are described with their chemical name. So, on a US label you'd read <a dir="ltr" href="https://www.theguardian.com/lifeandstyle/2015/sep/08/food-labeling-us-fda-eu-health-food-safety">"sodium caseinate", rather than "E469" </a>. On the surface, that would seem clearer, but even that convention is a little obtuse about what the stuff actually is: sodium caseinate is used in foods like sausages or bread, and is the main ingredient in coffee creamer, but neither its E number nor its chemical name would tell you that it's a protein derived from milk.

Another sodium-based difference between countries to be aware of is that the US lists sodium levels on its products (specifically its nutritional labels, which we'll cover next), whereas the EU lists salt. Salt may be a type of sodium, but sodium is a category that also includes the caseinate additive we just mentioned, as well as other ingredients like bicarbonate of soda.

Nutrition facts

As your eye roves around a processed food packet, you will probably also come across some form of nutritional information too.

Some nations, like the UK, have a traffic light system for nutrition that expresses how healthy a processed food is in terms of fat, saturates, sugars and salt, using the colours red, amber and green. For example, a processed oven meal might have 7.7g of saturated fat, and so be labelled red. In some (but not all) cases, it also comes with a percentage, in this case 39%. The colour scheme was designed to be intuitively easy to understand, but how the percentages are worked out may not be immediately obvious. The 39% in that meal is calculated using the "Reference Intake", which is the maximum recommended amount. In Europe, this value has gradually been replacing "Guideline Daily Amounts" (GDA) on labelling, which differed by gender and age.

The traffic light system, which appears on the front of UK food, offers a quick and clear message for nutritional value (Credit: Alamy)

Unlike GDAs, the Reference Intakes are single figures – 90g sugars or 20g of saturated fat, for instance. What is perhaps less obvious to the average consumer is that they are the recommended maximum intake for an <a dir="ltr" href="https://www.nhs.uk/live-well/eat-well/what-are-reference-intakes-on-food-labels/">adult woman who does an average amount of physical activity </a>. If the Reference Intake was based on the nutritional maximums recommended for the average adult man, which are sometimes higher, then it would risk women unwittingly eating too much.

So, if the saturated fat in the meal pictured above had been labelled based on UK health guidelines for men aged 19-64 (which is <a dir="ltr" href="https://www.nhs.uk/live-well/eat-well/eat-less-saturated-fat/">no more than 30g per day </a>), the percentage would actually be more like 26% – clearly that's still not healthy, but it's lower.

However, it's not like British men are reading these labels and undereating – <a dir="ltr" href="https://www.bbc.co.uk/news/health-53514170">it's the opposite </a>. And one recent survey found that <a dir="ltr" href="https://yougov.co.uk/topics/politics/articles-reports/2017/04/11/only-one-ten-brits-are-checking-all-traffic-light-">a third of British men say they ignore nutritional labels </a>, compared to one in six women.

The Nutrition Facts label was one of the most ambitious public health initiatives ever undertaken by the FDA

Decisions about how labels should account for sex differences – along with various other dilemmas – also played out in the US a few decades ago, when the Food and Drink Administration was designing its ubiquitous "Nutrition Facts", a label that <a dir="ltr" href="https://extranet.who.int/nutrition/gina/en/node/8006">legislators in 1990 </a>mandated should appear on pretty much all food packaging in the US.

The US Nutrition Facts label was updated in 2016, but has been mandatory on foods since the 1990s (Credit: FDA)

Navigating opposition from foodmakers and politicians, the Nutrition Facts label was "one of the most ambitious public health initiatives ever undertaken by the FDA", its <a dir="ltr" href="https://downloads.regulations.gov/FDA-2012-N-1210-0002/attachment_199.pdf">designers later wrote </a>. It went through various iterations, and was scientifically tested on consumers to see how well they read and understood it.

"Nothing in the legislation specified what the label should look like, but we knew that it had to employ the science of graphic design to nudge behaviour. In the lingo of marketers, it had to 'pop'," <a dir="ltr" href="http://www3.med.unipmn.it/papers/2014/NEJM/2014-07-17_nejm/nejmp1402971.pdf">wrote David Kessler, former commissioner of the FDA, in 2014. </a>This included details such as black and white colouring to provide strong contrast, eliminating punctuation marks to improve readability, and even fiddling with the specific distance between the lines to ensure clarity.

Below you can see the design evolution up to the 1990s version, experimenting with pie charts, bars and other graphical presentations:

The pre-1990s label (top left), followed by four potential designs, and the one eventually approved (bottom right) (Credit: Jerold Mande/FDA/Burkey Belser/Erika Ritzer)

The FDA team also had to make a series of pivotal decisions about how and what nutrition information to display. The US version of Reference Intake was dubbed "Daily Value", and like in Europe, the FDA had to balance the needs of men and women. In the early 1990s, the recommendations of caloric intake for adults ranged from 1,900 calories per day for women over 51 to 3,000 for men 15-18 years of age. At first, the FDA toyed with the idea of using a population-weighted average of 2,350 calories, but they settled on 2,000 calories, arguing that overconsumption in women was the greater risk.

Another major set of decisions for the FDA involved the official definitions of "serving size", which would seem obvious at first, but is actually complex to define. Until the Nutrition Facts label arrived, each manufacturer got to decide how big a portion was. This led to all sorts of trickery: a cake could be presented as "light" by simply cutting the serving size on the label, rather than the fat or sugar content.

A cake could be presented as "light" by simply cutting the serving size on the label, rather than the fat or sugar content

The 1990 legislation had mandated that serving size should be the amount "customarily consumed and which is expressed in a common household measure that is appropriate to the food". But as <a dir="ltr" href="https://downloads.regulations.gov/FDA-2012-N-1210-0002/attachment_199.pdf">the FDA team soon discovered </a>, calculating serving sizes for the full smorgasbord of American food was quite the task, involving myriad national surveys to establish how much people ate.

So, for example, the serving size for cookies was fixed at 30g, or thereabouts (so two 18g cookies would still equal a serving size). Some categories, though, provided the researchers with a real challenge: for instance, they couldn't make a single serving rule for "breakfast cereal", because granola, for instance, is much heavier than cornflakes.

In the end, they <a dir="ltr" href="https://www.regulations.gov/document/FDA-2004-N-0258-0136">defined 139 categories </a>, which includes four types of cereal, four types of cheese, and a host of definitions for desserts and cakes, from "heavyweight cake" to "lightweight cake". (Cake frosting, incidentally, also has its own category, if you are partial to that – and it's two tablespoons.)

The US serving size for ice cream was revised recently, to reflect that Americans were eating larger portions (Credit: Carlo Allegri/Getty Images)

The US serving sizes <a dir="ltr" href="https://www.fda.gov/food/food-labeling-nutrition/changes-nutrition-facts-label">changed again in 2016 </a>, notably for ice cream and for soda. Either the original estimates were inaccurate, or Americans now eat more ice cream and drink more fizzy drinks. Either way, the FDA changed a serving of ice cream from half a cup to two-thirds (one cup of ice cream is around 150g), and ditched the reference amount of 8oz (227ml) for a serving of soda. The 2016 change also accommodated the fact that bottle sizes are now bigger: so whether you pick up a 12oz (355ml) or 20oz (568ml) of sugary soda, both will be labelled as a single serving.

Crucially, if it's not already clear by now, what you ought to know when you see the words "serving size" on a label is that it is not a recommended amount, rather it is the typical portion that the average American actually consumes – and that's not always an amount that adds up to a healthy diet.

Health and nutrition claims

A final piece of label decoding involves health claims, which are regulated to avoid manufacturers over-promising. Laws differ internationally, but in the US, there are <a dir="ltr" href="https://www.fda.gov/food/food-labeling-nutrition/questions-and-answers-health-claims-food-labeling">three types of claim </a>that are relevant: "authorised", "qualified", and "structure-function" claims. Knowing which is which can help to gauge how much weight to give the claim when making diet choices.

An example of an <a dir="ltr" href="https://www.fda.gov/food/food-labeling-nutrition/authorized-health-claims-meet-significant-scientific-agreement-ssa-standard">authorised claim </a>, on a low sodium packet, might be: "Diets low in sodium may reduce the risk of high blood pressure, a disease associated with many factors". To have this approved by the FDA, there must be "significant scientific agreement".

A <a dir="ltr" href="https://www.fda.gov/food/food-labeling-nutrition/qualified-health-claims-letters-enforcement-discretion">qualified health claim </a>has more nuance, reflecting the fact that the science is not settled. It might go something like: "Scientific evidence suggests, but does not prove, that whole grains, as part of a low-saturated-fat, low-cholesterol diet, may reduce the risk of diabetes".

Finally, a <a dir="ltr" href="https://www.fda.gov/food/food-labeling-nutrition/structurefunction-claims">structure-function claim </a>is intentionally vague, such as "calcium builds strong bones". The key with these assertions is that they don't (and can't) make any specific promises to improve health, and should be viewed only as marketing language.

A range of breakfast cereals aimed at children in Spain (Credit: Getty Images)

Using typography tricks and small print, many manufacturers – in the US and all over the world – try to amp up health benefits and fade back downsides. In one recent study of breakfast cereal in Australia, for example, 83% of children's cereals touted a <a dir="ltr" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6683094/">nutrition or health claim </a>, such as "high fibre" or "low salt", yet a majority were rated as unhealthy or nutritionally poor overall. Among other notorious examples on the supermarket shelf are the <a dir="ltr" href="https://www.bbc.co.uk/news/health-45565364">"low fat" yoghurts that should really be labelled "high sugar". </a>

No matter which country you live in, then, it's prudent to do some background research about what you see on a label. While it might seem comprehensive and detailed, there's often more to the health claims, ingredients or nutritional information than can be displayed on the packet. The labelling of foods has come a long way since the days milk contained formaldehyde and candy came with arsenic – but that doesn't mean that a label tells you everything.

* Richard Fisher is a senior journalist for BBC Future. Twitter: <a dir="ltr" href="https://twitter.com/rifish">@rifish </a>.

Deborah Blum was Fisher's supervisor during a fellowship he completed between 2019-20 at Massachusetts Institute of Technology.

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How to decode a food label

Sleep paralysis is a neurological phenomenon in which a person awakens from sleep but is temporarily paralyzed.
The episode may last a few seconds to minutes and is accompanied by the strangest hallucinations. It can feel terrifying.

Sleep paralysis

Sleep paralysis often occurs when we take a nap, when jet-lagged or sleep-deprived. We wake up while still in the stage where vivid dreams occur, called the rapid eye movement sleep (REM).
During REM, the front brain - central to our ability to plan and think logically - turns off and makes our bodies temporarily paralyzed. It prevents us from acting out &quot;real&quot; dreams. Sometimes we wake up in this stage. The vivid and sometimes threatening dreaming of REM can &quot;spill over&quot; into conscious awakening. It can feel like a nightmare coming alive.

Neurological origins of sleep paralysis

Sleep paralysis can sometimes make us feel like we&#39;re floating outside our body. The out-of-body experience can reliably be reproduced in the laboratory by disrupting the temporo-parietal junction in the brain. This region helps build a body image based on inputs it receives from the senses. The area is usually turned off during REM sleep.
In sleep paralysis, there is no feedback from the body telling the brain how to build the body image, resulting in out-of-body hallucinations such as seeing your body float in the air or sink deep into the bed.

Out-of-body experiences

The most distressing during sleep paralysis is seeing an intruder that sometimes attacks the sleeper. Anything the imagination can invent can happen. Commonly, the intruder chokes the person by crushing his chest. The creature can include details like a demonic face with sharp teeth and cat eyes.
One explanation is that in the same way that people who are born with a missing arm may experience phantom limbs - they feel the missing limb - a person can &#39;feel&#39; another phantom person during sleep paralysis.

Seeing a ghost

Research suggests that your beliefs about sleep paralysis can shape your experience.
In Denmark, people see sleep paralysis as something trivial caused by the brain. Egyptians fear dying from sleep paralysis and consequently have longer episodes. The fear will activate fear areas in the brain, making them more likely to wake up during REM. The escalating anxiety would worsen sleep paralysis, causing more intense bodily hallucinations.

Fear feeds terrifying sleep paralysis

<ul>
<li>Understanding what is happening during sleep paralysis helps to prevent fear cycles. People are relieved to hear they are not &quot;crazy&quot;.</li>
<li>Literally turn your back on the terrifying monster by dreaming a coherent dream in which you are aware you are dreaming.</li>
<li>Meditation relaxation (MR) therapy was designed to treat sleep paralysis. The treatment includes techniques of cognitive reappraisals, emotional distancing, meditation, and muscle relaxation.</li>
</ul>

Controlling sleep paralysis

Sleep paralysis, which 20 percent of people experience at least once, can be terrifying. Though it is a neurological phenomenon, our culture and beliefs can make the experience worse. One potential treatment is to learn to control the content of our dreams.

Neuroscience explains terrifying ordeals, from out-of-body experiences to alien abductions.

<ul><li>Sleep paralysis, which 20 percent of people experience at least once, can be terrifying. </li><li>Though it is a neurological phenomenon, our culture and beliefs can make the experience worse. </li><li>One potential treatment is to learn to control the content of our dreams. </li> </ul>

Imagine waking up in the middle of pitch darkness, only to realize you are completely paralyzed. You suddenly notice out of nowhere, an aggressive and horrendous human-like cat is on your bed. Next, the worst-case scenario unfolds: The creature viciously attacks you, and you vividly feel its razor-sharp teeth penetrating your flesh. Next morning, you wake up with a bruise on your body.

It sounds like something out of a Stephen King horror novel, but the events describe a real-life case of sleep paralysis, as my colleagues and I recently reported in a <a dir="ltr" href="http://www.ncbi.nlm.nih.gov/pubmed/25802016">study </a>conducted in Italy.

Sleep paralysis is a condition in which a person awakens from sleep but is temporarily paralyzed, unable to move or speak. The phenomenon, in fact, is not uncommon. Around 20 percent of people experience sleep paralysis at least once in their life.

Though the episodes of sleep paralysis are brief, lasting a few seconds to minutes, they are rich with mystery and potential insight into the nature of the human brain. How does sleep paralysis happen, and why does it accompany the strangest hallucinations?

<a dir="ltr" href="https://en.wikipedia.org/wiki/Sleep#/media/File:Albert_Anker_-_Schlafendes_M%C3%A4dchen_auf_einer_Holzbank.jpg">Credit </a>: Albert Anker via Wikipedia / Public domain

Sleep paralysis often occurs when we take a nap during the day, when jet lagged, or in any way, when sleep deprived. It happens when we wake up while still in a stage of sleep, called rapid eye movement sleep (REM), during which most vivid dreams occur. During REM, a part of the front brain called the dorsolateral prefrontal cortex, central to our ability to plan and think logically, turns off. This explains why our dreams during REM seem so real, and why the fabric of reality is so out of control when we dream — with warped landscapes and abruptly changing times, places, and people. (The Hollywood blockbuster Inception brilliantly captures the surreal flavor of dreams.)

To prevent us from acting out such intensely "real" dreams during REM and potentially hurting ourselves, our brain has a brilliant solution: it makes our bodies temporarily paralyzed.

REM is also the stage that most resembles wakefulness. Our blood pressure and heartbeat increase, and our breathing quickens. Even brain waves speed up, becoming virtually indistinguishable from wakefulness.

Sometimes, however, we actually do wake up while still in REM sleep. In a sense, we have a "switch" in the brain that tilts us between REM and wakefulness. And all it takes is a few neurochemicals to leave us stuck in this borderline state between parallel "realities" — sleep and wakefulness.

As if being paralyzed and unable to speak when waking up isn't chilling enough, occasionally, the vivid and sometimes threatening dreaming of REM can "spill over" into conscious awakening. This state — in medical jargon referred to as "sleep paralysis accompanied by hypnopompic hallucinations" — can best be described as a dream, or worse yet, a nightmare coming alive before our eyes.

Sleep paralysis can sometimes cause eerie sensations of floating outside one's body or looking down upon oneself from the bedroom ceiling. In certain cultures, such out-of-body experiences are attributed to the "soul" — a type of "astral travel" — where the spiritual self projects itself into an alternative realm of existence.

But out-of-body experiences originate in the brain. In fact, they can reliably be produced in the laboratory. We simply have to disrupt the activity of a brain region called the temporoparietal junction. This region helps us build a "body image" in the parietal lobes (the top-middle part of the brain) or a type of neural representation of the self, based on the inputs it receives from the senses. The temporoparietal junction, which is also critical for our ability to distinguish between "self" and "other," is normally turned off during REM sleep. This is why there is a loosening of the sense of self when we dream: we sometimes see ourselves from a third-person perspective, and other times the self occupies another person's body.

It is thought that similar disturbances in the temporoparietal junction can occur during sleep paralysis. When we realize we are paralyzed, the motor cortex in the brain immediately sends signals to the rest of the body to move and to overcome the paralysis. It also sends additional signals (sort of like "cc'ing" when emailing) to the parietal lobes. Normally, there is feedback from the limbs telling the brain how to build our body image but not during sleep paralysis.

The confusing signals received by the brain can influence how the brain builds our sense of "self," and the result is all kinds of bizarre bodily hallucinations, such as out-of-body experiences or seeing one's limbs or entire body rotate in the air like a tornado or sink deep into the bed as if drowning in quicksand.

<a dir="ltr" href="https://www.gettyimages.com/detail/news-photo/woman-dressed-up-as-a-zombie-nun-takes-part-in-the-news-photo/868759772?adppopup=true">Credit </a>: <a dir="ltr" href="https://www.gettyimages.com/search/photographer?family=editorial&amp;photographer=AFP+Contributor" rel="noopener noreferrer">AFP Contributor </a>via Getty Images

Perhaps more distressing than becoming a ghost is seeing one. Sleep paralysis is arguably most infamous for the sinister shadowy "bedroom-intruder" that sometimes attacks the sleeper. The "creature" is usually lurking in the distant dark, slowly approaching in on its victim.

From here, all kinds of ominous things can happen, as far as the imagination can stretch. Commonly, the intruder chokes and suffocates the person by crushing his chest or pressing on his neck. And occasionally, the creature brutally rapes the paralyzed sleeper. The figure often appears simply as a dark shadow, similar to the human size and shape. But, it can also include detailed features, say, a scary demonic face with animal characteristics, like sharp teeth and cat eyes.

This figure goes by different names around the world. My colleague Devon Hinton of Harvard Medical School and I found that in Egypt, the creature is thought to be a Jinn (an "evil genie") — a spirit-like entity that may hunt down, terrorize, and even kill its victims. In another study, we've discovered that among some Italians, it is believed to be a malevolent witch or a terrifying human-like cat, known locally as the Pandafeche . Some space alien abduction cases also fit the sleep paralysis scenario: the person is laying in his bed paralyzed; suddenly the alien appears and begins to experiment on the sleeper's sexual organs, collecting eggs and semen.

<a dir="ltr" href="https://en.wikipedia.org/wiki/Temporoparietal_junction#/media/File:Brain_-_Lobes_-_Temporoparietal_junction.png">Credit </a>: John A Beal via Wikipedia and licensed under <a dir="ltr" href="https://creativecommons.org/licenses/by/2.5/">CC BY 2.5 </a>

UC-San Diego neuroscientist VS Ramachandran and I recently proposed a neurological explanation for why we see this shadowy creature during sleep paralysis.

The idea was sparked by research showing that people who are born with a missing arm may experience phantom limbs, meaning that they feel the presence of missing limbs. This led to the idea that there might be a "hardwired" template, or map, of a person's body surface in the right parietal lobe of the brain. So when a person born with no arm is experiencing a phantom arm, he is really feeling the presence of the "arm" that is part of his internal body map. This map would be connected to emotional and visual centers in the brain, causing us to be attracted to body shapes similar to our own. In other words, causing us as humans to be innately attracted to other humans, and not to, say, pigs (at least for most of us!).

More clues about such a hardwired body map come from a rare disorder called apotemnophilia, in which a person has a desire to have a limb amputated and is attracted to people with missing limbs.

Ramachandran and I suggested that a disturbance in the processing of "self" and "other" — at the temporoparietal junction — results in a hallucinated projection of one's own body map; the mind literally casts a shadow, just like the body does. As the barrier between self and other dissolves, the person mistakes his own "shadow" (or body template) for a separate entity.

Compare this to an out-of-body experience: here your sense of self is shifted and you identify with your "ghostly self," not your "bodily self." When you see a "ghost," on the other hand, your vantage point doesn't get shifted, and you identify with your "bodily self," instead of your "ghostly self." And with the "threat detection system" of the brain on high alert (also known as threat hypervigilance), we are even more likely to interpret the human-like shadow as an evil, other entity.

Moreover, our brain regards it as highly improbable that chest pressure, sensations of suffocation, rapid breathing (which are caused by REM physiology), and — on top of everything — seeing a human-like shadow, occur by random chance. When REM dreaming becomes activated as well, the shadowy figure can take on all kinds of sophisticated shapes and dimensions, and the entire plot thickens. At this point, memory and the narrative abilities of other brain regions play a role in the evolving hallucination.

While our neurological explanation for the shadowy figure has yet to be proven, it fits well with previous observations. It has been shown that occasionally when the temporoparietal junction is disrupted using an electric current, instead of having an out-of-body experience, the person senses the presence of a shadowy figure. This figure is perceived to stand behind the person and to mimic his posture; even though the person is aware that the postural features of the shadowy figure are similar to his, he still regards it as a separate person. Based on this, the scientists who conducted the <a dir="ltr" href="http://www.nature.com/nature/journal/v443/n7109/full/443287a.html">study </a>concluded that they had created a "ghost-like" double.

<a dir="ltr" href="https://en.wikipedia.org/wiki/Sleep_paralysis#/media/File:John_Henry_Fuseli_-_The_Nightmare.JPG">Credit </a>: <a dir="ltr" href="https://en.wikipedia.org/wiki/en:Henry_Fuseli" rel="noopener noreferrer" title="w:en:Henry Fuseli">Henry Fuseli </a>via Wikipedia / Public domain

In the 1986 Stephen King horror Novel It , the clown-like killer exploits the fears of its victims to hunt down its prey — young children who fear monsters. Although fictional, literature is sometimes closer to science than one would think. Our own research suggests that one's beliefs about sleep paralysis can profoundly shape the experience.

In one study, Devon Hinton and I found that in Denmark, people regard their sleep paralysis as something trivial caused by the brain. In sharp contrast, we found Egyptians often hold very specific cultural and supernatural beliefs about theirs. In another study, we discovered that Egyptians experiencing sleep paralysis not only fear it much more than Danes do — to the extent that many fear dying from it — but they also have longer episodes and on average experience sleep paralysis three times more often.

These findings strongly indicate that for Egyptians, beliefs have radically transformed the experience — a form of mind-body interaction — causing not only psychological fear but also conditioned physiological fear of sleep paralysis. When they go to bed, they fear the "cultural creature" might attack them. Ironically, this will activate fear centers in the brain (such as the amygdala), making them more likely to wake up during REM and have sleep paralysis. And once they have sleep paralysis, they interpret it in light of their cultural beliefs, thinking, "I am being attacked by an evil spirit," making them even more terrified. Escalating fear and arousal would worsen sleep paralysis by prolonging the episode and resulting in more intense bodily hallucinations, as they are more likely to try to move during the paralysis, causing body image disturbances.

It doesn't end there. Now, they notice that they are experiencing sleep paralysis more often and that episodes are longer and more horrifying. They become convinced that they are targeted, perhaps even possessed, by a supernatural creature. This, in turn, makes them even more afraid, and the vicious cycle continues to feed on itself.

It is still unclear whether the fear generated by sleep paralysis can be pathological. But in our recent study, to be published soon, we found that experiencers of sleep paralysis in Egypt have greater symptoms of trauma and anxiety compared to those who have never experienced it. Intriguingly, we also found that those who experience hallucinations during their sleep paralysis have more trauma and anxiety symptoms. These findings point to the possibility that sleep paralysis, if accompanied by certain beliefs, might be a traumatizing experience. This is also consistent with the findings of Richard McNally, also at Harvard, that sleep paralysis interpreted as alien abduction can elicit physiological fear comparable to patients with post-traumatic stress disorder.

In the 1984 horror movie A Nightmare on Elm Street , the ghost Freddy Krueger ferociously terrorizes and kills young teenagers during their nightmares. But the protagonist Nancy is finally able to make Krueger vanish from her nightmares; she follows the advice of her friend Glen (played by a young Johnny Depp), who insists that if you turn your back on the monster, you "take away its energy and it disappears."

Indeed, dispelling the fear surrounding sleep paralysis is an important means to help people cope with their experience and, crucially, to prevent escalating fear cycles that can lead to worse and more frequent episodes. One way to do this is to disseminate scientific knowledge about the experience. This often works. People are genuinely relieved to hear that they aren't "crazy," that they aren't the only ones experiencing it, and that the phenomena seem to originate in the brain.

A more radical approach to overcome the fear of sleep paralysis is by "literally" turning your back on the terrifying monster, by sliding into a lucid dream — that is, a dream in which you are aware that you are dreaming. It is not surprising that sleep paralysis can be a gateway to lucid dreaming. Both sleep paralysis and lucid dreaming are consciousness states that lie between REM and wakening; the former is dreaming while awake; the latter, being awake while dreaming.

Neural circuitry associated with wakefulness is more likely to become activated during sleep paralysis, such as the dorsolateral prefrontal cortex that helps us organize our logical thoughts when awake (and which is normally turned off during REM). When the dorsolateral prefrontal cortex becomes active during sleep, we enter a type of hybrid consciousness that combines the surrealness of dreams and the rationality of wakefulness. And so, we become aware that we are dreaming — and like a great Michelangelo we can create our own fantasy worlds composed of colorful landscapes and creatures of all kinds conjured by our minds. Being able to manipulate the content of one's sleep paralysis hallucinations and REM-dream imagery could give the experiencer a sense of control over the situation and might therefore be therapeutic.

I was once able to slide into a lucid dream during my own sleep paralysis. Lucky for me, no terrifying intruders were present. When I became aware that my dreaming "self" was walking around in my bedroom, it occurred to me to do an "experiment." I found a piece of scrap paper on the floor and put it in my pocket. I thought to myself, if it's still there upon awakening, I would have to reconsider some of my own scientific theories about the role of the brain in favor of more uncanny explanations. My pocket was empty when I woke up.

On a different occasion, I wanted to test whether by deliberately trying to move during the paralysis (causing disturbances to my body image) and imagining that a sinister creature was present in my bedroom (activating dream imagery), I could create my own hallucinated "Frankenstein monster." I wasn't able to complete the "experiment" out of sheer horror, but I still joke with my colleagues telling them that we're among a select group of people who can say we're working while sleeping.

Based on my scientific work on sleep paralysis around the world and our proposed neurological explanation for why people hallucinate ghosts during the episode, I thought to myself, "How do I create a simple, yet effective therapy for sufferers?" Meditation-relaxation (MR) therapy was recently designed as a direct treatment for sleep paralysis. The <a dir="ltr" href="http://vanwinkles.com/the-demon-vanquisher">treatment </a>, which includes techniques of cognitive reappraisals and emotional distancing, meditation, and muscle relaxation, aims to minimize current attacks and decrease the frequency, severity, and duration of future ones. In a recent pilot study, we found that MR therapy reduced sleep paralysis episodes by 50+ percent when applied for eight weeks in patient with narcolepsy.

As we are just beginning to probe this fascinating condition and unlock its neural basis, the mystery remains. Here is a single phenomenon that can make us see and become ghosts, have encounters with space aliens from distant galaxies, and plunge us into far and exotic lands of lucid dreaming, where we are the sculptors of our own realities, all the while laying silently in our beds. It shows us firsthand how the feeling of a sense of self as a unified entity separate from others arises in the brain and how vulnerable this feeling is to disruption.

Dr. Baland S. Jalal is a researcher at Harvard University, Department of Psychology and visiting researcher at Cambridge University, Department of Psychiatry. He obtained his PhD at Cambridge University in the School of Clinical Medicine (Trinity College Cambridge) and was a Fellow at Harvard University (2016, 2018). He is a close collaborator and co-author on 10 papers with the renowned neuroscientist VS Ramachandran (2011 TIME magazine 100 most influential people in the world).

Sleep paralysis: a terrifying encounter with our own mind

Your immune system defends your body from infection. If you can support it, there will be benefits.
Your immune system creates, stores, and distributes white blood cells that fight bacteria and viruses you are exposed to.

Your immune system is your friend

<ul>
<li>Eating fruits and vegetables helps your immune system fight viruses and bacteria.</li>
<li>A positive attitude can help your body fight illnesses.</li>
<li>Covering your mouth when you cough or sneeze can keep germs at bay.</li>
<li>Sucking your baby&#39;s pacifier can make them less likely to develop allergies, a recent study found.</li>
</ul>

Facts about the immune system

<ul>
<li>A lack of sleep does not affect your immune system. There is a strong link between restorative sleep and a healthy immune system.</li>
<li>Supplements can help you get better faster. Taking megadoses of one vitamin has not been proven to support the immune system.</li>
<li>Kids need supplements. They really should get vitamins and minerals from eating nutritious foods.</li>
<li>Exercise does not affect the immune system. Exercise lowers blood pressure, keeps body weight under control and can protect you from some diseases.</li>
</ul>

Immune system myths

What do you really know when it comes to boosting your immune system and fighting off a cold?

Your immune system is your friend. It protects your body from infection. Give it your full support and, as with any friend, there will be perks.

Here’s how it works: Your immune system creates, stores, and distributes the white <a data-crosslink-type="article" data-metrics-link="" dir="ltr" href="https://www.webmd.com/heart/anatomy-picture-of-blood">blood cells </a>that fight bacteria and viruses that enter your body, especially during cold and flu season.

For such a simple-sounding process, there's a lot of bad information out there. Here are some myths and facts about the immune system and how it works.

Eating fruits and veggies keeps your immune system strong.

Fact. Mom and dad were right when they told you to eat your <a data-crosslink-type="slideshow" data-metrics-link="" dir="ltr" href="https://www.webmd.com/food-recipes/ss/slideshow-exotic-fruits">fruits and vegetables </a>. Studies show that people who eat a lot of them get sick less. The nutrients in them can help your immune system fight viruses and bacteria.

Not getting enough sleep has no effect on your immune system.

Myth. There's a strong link between sleep and a healthy immune system. But not just any <a data-crosslink-type="slideshow" data-metrics-link="" dir="ltr" href="https://www.webmd.com/sleep-disorders/ss/slideshow-sleep-disorders-overview">sleep </a>will do. Restorative <a data-crosslink-type="tools" data-metrics-link="" dir="ltr" href="https://www.webmd.com/sleep-disorders/sleep-habits-assessment">sleep </a>, which means <a data-crosslink-type="article" data-metrics-link="" dir="ltr" href="https://www.webmd.com/sleep-disorders/sleep-requirements">enough sleep </a>to get the body back into fighting shape, is key.

Sleep needs vary by person, but most adults need 7-8 hours a night. Teens need 9-10 hours, school-aged kids need at least 10 hours, <a data-crosslink-type="article" data-metrics-link="" dir="ltr" href="https://www.webmd.com/parenting/guide/parenting-preschoolers-mistakes">preschoolers </a>need 11-12 hours, and newborns need 16-18 hours.

Over the past few decades, though, the average time asleep has dropped to less than 7 hours a night for adults. If you sleep less than your body needs, you’ll build up a sleep debt. And you can't make that up with naps or by sleeping in on weekends. Bottom line: Get to bed at a time when you know you can sleep at least 7 hours.

Fact. A good outlook may be good for your health. One study of law students showed that their immune systems kept pace with their thoughts about how tough school would be. When they felt better about school, they had a better immune system. When they were worried, their immune system slowed. The upshot: Looking on the bright side might better equip your body to fight illnesses.

Myths vs. Facts About Boosting Your Immune Sytem

A simple look at our brain, we would see a blob of jiggly meat, however, this blob of jiggly meat is extremely powerful. Through years of evolution, our brains are responsible for conjuring our pasts and predicting our futures, control our bodies, and create our experiences in the past and the present.
Our brains can also modify our physical reality through a social reality where we can make up something out of nothing and convince other people to treat it as real.

The Superhuman Power Of The Brain

Our brains rely on memories when faced with ambiguous data whereas it guesses the causes of the data received as it plans what to do next in order to keep us alive and well.
An esteemed neuroscientist described our daily experience as &quot;the remembered present&quot; where our brains will constantly and invisibly guess future actions based on memories that are similar to the present moment. Our brain&#39;s guesses, may they be right or wrong, manifests as our actions and senses.

Reverse Inference Problem

Our brains can actually consider physical objects and impose new or different functions on it even if it is not a part of its physical nature, using only our collective minds. This phenomenon is called social reality.
It has an amazing level of influence on our lives, not only on an individual level but the effects can be felt globally. Where we believe a certain stereotype, soon it creates a self-fulling prophecy which perpetuates the stereotype in a vicious cycle.

Social Reality

The brain makes categories based on context. Say an elephant, a fountain, and a water gun are all three different objects, however, the brain can categorize them as &quot;objects that can shoot water.&quot;
The categories made by the brain are extremely flexible and are what drives many of our actions and experiences. this is also the engine behind social reality because when we share such categorizations and make them real it is able to influence people as well as our genetic evolution as a species.

Abstract Categories

&quot;We have more control over reality than we might think, and more responsibility for reality than we might realize or want&quot;.

Do we see the world as it really is, or are we creating our own reality? We delve into the neuroscience behind the world that we experience.

There is a classic Monty Python sketch in which a customer, played by John Cleese, enters a pet shop to buy a cat. The dodgy shopkeeper, played by Michael Palin, whips out a terrier instead and offers to convert the dog surgically into a cat, a budgie, or a fish.

“Terriers make lovely fish,” he assures the customer. “I could do that for you straight away. Legs off, fins on, stick a little pipe through the back of its neck so it can breathe, bit of gold paint…” In real life, we often view our pets in terms of other animals, and no scalpel is required.

Perhaps you’ve met dogs who are so aloof that they seem like cats, or cats who are so affiliative that they’re more like dogs. My family used to have a pet betta fish named Ariel who seemed more puppy than fish. She’d allow us to pet her without complaint, and when we dropped food in the fish tank she’d nuzzle our fingers.

This topic might seem frivolous, but it reveals a superpower of the human brain. We can consider a physical object, such as a fish, and impose new functions on it that are not part of its physical nature, using only our collective minds. To my family, Ariel was a puppy, even though nothing about her body was dog-like.

We simply agreed that Ariel had puppyish qualities, and that agreement became our reality. (The perceptive reader may have noticed that I’ve referred to Ariel as ‘she’, even though the colourful bettas sold in pet shops are always male. Our daughter, who was three at the time and in love with Walt Disney’s The Little Mermaid , informed us in no uncertain terms of Ariel’s preferred pronoun.)

Read more about the brain:

This superpower to modify physical reality is called ‘social reality’. You or I can simply make something up and communicate it to other people, and if they treat it as real, it becomes real. For better or for worse.

Social reality has an astonishing level of influence on our lives. We impose functions on bits of paper and metal and they become money. We draw imaginary lines in the dirt and they become the borders of a country, and the people on opposite sides of those imagined lines transform into citizens with rights, and foreigners without them.

Brexit is also social reality. Even your own name is social reality. Someone just made it up, and you and other people treat it as real. In fact, most of us spend most of our time in a real world of serious make-believe.

How your brain deals with sensory information

How do human brains create social reality? To answer this, let’s consider it from a brain’s point of view. For your whole life, your brain is trapped inside a dark, silent box called your skull.

Your brain constantly receives data from your eyes, ears, nose, and other sense organs. It also receives a continuous stream of sense data from inside your body as your lungs expand, your heart beats, your temperature changes, and the rest of your insides carry on their symphony of activity.

All this data presents a mystery to your brain-in-a-box. Together, the data represents the end result of some set of causes that are unknown.

When something in the world produces a change in air pressure that you hear as a loud bang, some potential causes could be a door slamming, a gunshot, or a fish tank toppling to the floor. When your stomach unleashes a gurgle, the cause might be hunger, indigestion, nervousness, or love.

So, your brain has a problem to solve, which philosophers call a ‘reverse inference problem’. Faced with ambiguous data, your brain must somehow guess the causes of that data as it plans what to do next, so it can keep you alive and well.

Fortunately, your brain has another source of information that can help with this task: memory. Your brain can draw on your lifetime of past experiences, some of which were similar to the present moment, to guess the meaning of the sense data.

A slammed door, rather than a fish tank, may well be the best candidate for a loud bang if, for example, there is a strong breeze blowing through a nearby window, or if your heartbroken lover has just stormed out of the room and you’ve experienced similar exits in past relationships.

Your brain’s best guess – right or wrong – manifests itself as your action and everything you see, hear, smell, taste and feel in that moment. And this whirlwind of mental construction all happens in the blink of an eye, completely outside of your awareness.

The esteemed neuroscientist Gerald Edelman described daily experience as “the remembered present”. You might feel like you simply react to events that happen around you, but in fact, your brain constantly and invisibly guesses what to do next and what you will experience next, based on memories that are similar to the present moment.

A key word here is ‘similar’. The brain doesn’t need an exact match. If you saw Ariel the betta for the first time, your brain could guess that she’s a fish because you’ve seen similar fish before in bowls. Likewise, you have no trouble climbing a new, unfamiliar staircase because you’ve climbed staircases in the past. So similarity is enough for your brain to help you survive and thrive in the world.

Read more about how the brain works:

In psychology and philosophy, things that are similar to one another form a category. For example, think about fish, a common-sense category that includes many taxonomic groups of aquatic animals. Fish come in all colours, shapes and sizes. They swim with a variety of motions. Some travel in schools and others are solitary. Some live in oceans, some in ponds, and some in human homes.

A typical fish may have fins and scales and breathe underwater, but some fish have no scales (such as sharks), some have no fins (such as the hagfish), and a few can breathe on land (such as the lungfish). Despite this, we still consider all of these creatures similar and call them fish. We would never consider a dog to be a fish (Michael Palin’s creation notwithstanding).

You might think that categories exist in the outside world, but in fact, your brain makes them. If I ask you to imagine a fish as a pet, your brain creates a category that could include bettas, goldfish and guppies. But if I ask you to imagine a fish in a restaurant, your brain would more likely build a category from cod, haddock and salmon. So a category like ‘fish’ is not something static in your brain. It is an abstract category that your brain creates, based on context.

The most important similarities forming a category like ‘fish’ are not about physical looks but about function. You don’t eat a betta sandwich for lunch or keep a salmon in an aquarium, because the function of a pet is different from the function of a meal.

Similarly, the function of a fishbowl is usually to hold live fish, but in another context it can become a vase for flowers, a container for pencils or spare change, a drinking bowl for a thirsty dog, a fire extinguisher for a small blaze, or even a weapon to hurl at an attacker.

How social reality creates physical reality

Abstract categories are tremendously flexible. Consider the following three objects: a bottle of water, an elephant and a pistol. These objects do not look alike, feel alike, smell alike, or have any other obvious physical similarities. It turns out that they do share a physical function: they can all squirt water. So they form a category.

But they also share another function that, unlike water-squirting, is completely untethered from their physical nature. They are members of the category, ‘things that would fail to pass through airport security’. This purely abstract category is only based on function and is a product of human minds (other members of this category include cocaine, the Sahara Desert, and loud, rude songs about immigration officials).

Purely abstract categories, in fact, drive many of your actions and experiences. When your brain makes guesses about the sense data around and within you, those guesses often form an abstract category based on function.

To explain a feeling of shortness of breath, your brain might construct a category containing physical exercise, a punch in the gut, surprise, lust and a hundred other potential causes that are all similar to the present moment, so it can whittle them down and act. Category construction is the process by which your brain figures out what something is, what to do about it, and how it should regulate your organs, hormones and immune system as it prepares for action.

.css-d7z4j9{font-family:'Source Sans Pro',sans-serif;font-size:2rem;line-height:2.5rem;letter-spacing:-0.125%;font-weight:700;}The Worst Nuclear Accident