Here's a useful analogy for why sleep is so important. Imagine that your health and energy are a bucket of water. In your day-to-day life, there are things that fill your bucket up. Sleep is one of the main inputs. These are also things like nutrition, meditation, stretching, laughter, and other forms of recovery.There are also forces that drain the water from your bucket. These are outputs like lifting weights or running, stress from work or school, relationship problems, or other forms of stress and anxiety. <a href="https://jamesclear.com/sleep#footnote-5-17404">5</a>

Finally, sleep is paramount for metabolic health.<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2951287/">Studies</a>have shown that when you sleep 5.5 hours per night instead of 8.5 hours per night, a lower proportion of the energy you burn comes from fat, while more comes from carbohydrate and protein. This can predispose you to fat gain and muscle loss. Additionally, insufficient sleep or abnormal sleep cycles can lead to insulin insensitivity and <a href="https://www.nature.com/nutd/journal/v3/n5/full/nutd20138a.html">metabolic syndrome</a>, increasing your risk of diabetes and heart disease.

The quality of your sleep is determined by a process called the sleep-wake cycle.There are two important parts of the sleep-wake cycle:<ol><li>Slow wave sleep (also known as deep sleep)</li><li>REM sleep (REM stands for Rapid Eye Movement)</li></ol>During slow wave sleep the body relaxes, breathing becomes more regular, blood pressure falls, and the brain becomes less responsive to external stimuli, which makes it more difficult to wake up. This phase is critical for renewal and repair of the body. During slow wave sleep, the pituitary gland releases growth hormone, which stimulates tissue growth and muscle repair. Researchers also believe that the body's immune system is repaired during this stage. Slow wave sleep is particularly critical if you're an athlete. You'll often hear about professional athletes like Roger Federer or LeBron James sleeping 11 or 12 hours per night. <a href="https://jamesclear.com/sleep#footnote-8-17404">8</a>

But what is sleep, exactly? Why is it so important and so restorative for our bodies and minds? How does it impact our lives when we are awake? Sleep serves multiple purposes that are essential to your brain and body. Let's break down some of the most important ones.The first purpose of sleep is restoration.Every day, your brain accumulates metabolic waste as it goes about its normal neural activities. While this is completely normal, too much accumulation of these waste products has been linked to neurological disorders such as Alzheimer's disease.

These outputs are cumulative. Even a little leak can result in significant water loss over time.If you want to keep your bucket full, you have two options.<ol><li>Refill your bucket on a regular basis. That means making time for sleep and recovery.</li><li>Let the stressors in your life accumulate and drain your bucket. Once you hit empty, your body will force you to rest through injury and illness.</li></ol>Recovery is not negotiable. You can either make time to rest and rejuvenate now or make time to be sick and injured later. Keep your bucket full. <a href="https://jamesclear.com/sleep#footnote-6-17404">6</a>

REM sleep is to the mind what slow wave sleep is to the body. The brain is relatively quiet during most sleep phases, but during REM your brain comes to life. REM sleep is when your brain dreams and re-organizes information. During this phase your brain clears out irrelevant information, boosts your memory by connecting the experiences of the last 24 hours to your previous experiences, and facilitates learning and neural growth. Your body temperature rises, your blood pressure increases, and your heart rate speeds up. Despite all of this activity, your body hardly moves. Typically, the REM phase occurs in short bursts about 3 to 5 times per night.

The way this process occurs is fairly remarkable:During sleep, brain cells actually shrink by 60 percent, allowing the brain's waste-removal system-called the glymphatic system-to essentially "take out the trash" more easily. The result? Your brain is restored during sleep, and you wake up refreshed and with a clear mind.The second purpose of sleep is memory consolidation.Sleep is crucial for <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3768102/">memory consolidation</a>, which is the process that maintains and strengthens your long-term memories. Insufficient or fragmented sleep can hamper your ability to form both concrete memories (facts and figures) and emotional memories.

Alright, so how do we get rid of metabolic waste? <a href="https://www.urmc.rochester.edu/news/story/3956/to-sleep-perchance-to-clean.aspx">Recent research</a>has suggested that sleep plays a crucial role in cleaning out the brain each night. While these toxins canbe flushed out during waking hours, researchers have found that clearance during sleep is as much as <a href="https://www.ncbi.nlm.nih.gov/pubmed/24199995">two-fold faster</a>than during waking hours.

If you want to learn how to sleep better, then you're in the right place. This guide will walk you through everything you need to know if you want to get better sleep. I'll explain the science of sleep and how it works, discuss why many people suffer from sleep deprivation without knowing it, and offer practical tips for getting better sleep and having more energy.

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Sleep Stages

REM