• it modulates the timing of the cortisol pulse: once every 24 hours, you're going to get a boost in cortisol. It's a healthy boost, it sets your temperature rhythm in motion, and it sets your level of alertness, focus, and mood.
• you want that cortisol pulse to happen as early in the day.  When this pulse comes in the afternoon, your temperature rhythm is going to be shifted late and that's actually a signature of depression and anxiety and difficulty falling asleep.
• when you don't get that light until a few hours later,  everything is shifted and you will find it difficult to fall asleep at night.

You can get bright light from electronic devices early in the day but it's not enough. You need photons from sunlight

• If you live in Scandinavia, or in the depths of winter, don't buy an expensive daytime simulator, get one of these led light boxes for drawing they're very inexpensive in comparison;
• put that on your desk and just look at that thing for a few minutes in the morning. It's not as good, but better than being in the darkness; then when the sun's out getting outside.
• in winter, you want to go through every bit of effort to double or triple the amount of time that you're spending outside in the morning, so instead of 10 minutes make it 30 minutes.

Dopamine's main role in the brain and body is to drive motivation, craving, and pursuit.

It is not the molecule of pleasure, it is the molecule of drive. It is life force.

They both clear out the adenosine from our bodies.

Delay the intake of caffeine by 60 to 90  minutes after waking, and allow the adenosine to be cleared out of your system (it's not only cleared out In sleep, it's also cleared out in that kind of sleepy state of early morning). The other thing that clears it out - is exercise.

The longer we are awake the longer the buildup of something called adenosine in the brain and body;  adenosine turns on the parasympathetic nervous system and suppresses the sympathetic nervous system.  When we sleep adenosine is pushed back down. Caffeine effectively, through some chemical steps, blocks the effects of adenosine.

• If you're waking up naturally, without an alarm, that means that your temperature is starting to rise at that time that's why you wake up.
• that temperature increase triggers that cortisol release now and that's why some people wake up right before their alarm clock it's this cortisol pulse.

You wake up because of an increase in core body temperature, and that increase in core body temperature triggers that increase in cortisol; the clocks of your body are matched to this cortisol pulse so viewing bright light in the morning anchors it (so it happens every day around the same time).

Sometime around 2-3 PM, you're going to hit your temperature maximum: you might feel a  little sleepy at that time but that's actually the time in which your gut your all your systems are kind of revving at the maximum capacity.

Then it's going to start to drop and that drop in temperature eventually will be a full one to 3 degrees below what your temperature maximum is and that's when you're going to get sleepy and fall asleep. This is why it's important to keep the room cool at night to fall asleep.

The goal is to increase body temperature in order to be awake and to decrease the body temperature in order to be asleep.

Exercising will increase body temperature, somewhat paradoxically getting into a cold shower or cold water is going to increase it.