How Sleep Works
Importance of Sleep
Sleep resets our ability to be focused, alert, and emotionally stable in the wakeful period.
Sleep and wakefulness are tethered to one another.
- what we do in the wakeful state determines when we fall asleep, how quickly we fall asleep, and whether or not we stay asleep
How Sleep Works
Sleep is governed by two forces:
- Adenosine
- Circadian Rhythm
Adenosine
Adenosine is a molecule in our nervous system and body that builds up the longer we are awake.
- low level in brain and body after sleep
- high levels after being awake for long time
Adenosine create a sort of sleep hunger. Adenosine naturally builds up in your body the longer you are awake.
Caffeine
Caffeine acts as an adenosine antagonist by binding to the adenosine receptor.
- Blocks adenosine build up
- Once caffeine wears off, adenosine will bind with even greater affinity
- This is the crash that makes you feel especially tired
Caffeine tolerance varies per person due to genetic variations in terms of their adenosine receptors.
Caffeine increases dopamine, a neuromodulator molecule.
Circadian Rhythm
Circadian means about one day, or 24 hours.
- Our internal clock
- exists in the brain of every animal we’re aware of
The circadian rhythm determines
- when we are sleepy
- when we are awake
Your circadian rhythm is primarily governed by light, specifically sunlight.
- also affected by:
- timing of food intake
- timing of exercise
- drugs
How Waking Works
A hormone is a chemical that is released from one organ in your body and acts on other organs elsewhere in the body, including the nervous system.
A person wakes up in the morning due to a hormone called cortisol is released from your adrenal glands. There is also a release of epinephrine (adrenaline) from adrenals and in the brain.
This alerts your whole body to:
- increase heart rate
- tense muscles
- start moving
It is very important that this cortisol pulse comes early in the day.
When you wake up, an internal timer is set off in your body and the nervous system that dictates when the hormone melatonin, which makes you sleepy, will be released from the pineal gland.
- releases about 12-14 hours later
- Melatonin only comes from the pineal gland
- Melatonin can be thought of as the sleepiness signal
Light’s Role in Regulating Sleep
Light comes into your eyes through a set of neurons called retinal ganglion cells.
One type of retinal ganglion cells perceives a particular type of light and communicates that to the internal central clock known as the suprachiasmatic nucleus.
- The suprachiasmatic nucleus has connections to every cell and organ of the body
Important
Getting light to this central clock is vital in timing the release of cortisol and melatonin properly.
Our cells respond best to a particular quality and amount of light that come from sunlight called low solar angle sunlight.
- within 1-2 hours of sunrise
- within 1 hour of sunset
Artificial light can activate these cells, but not optimally.
- sunlight through a window or glass is 50x less effective
- with sunglasses it is 100-1000x less effective
The longer you are awake, the more sensitive to light these cells become.
Sunrise
It is optimal to get sunlight in your eyes as close to waking as possible.
- about 2-10 minutes of sunlight exposure
Bringing the cortisol pulse earlier in your wakeful period, earlier in the day has a number of benefits:
- positive effect on blood pressure, mental health, and more
Tip
Sunlight is 1,000-10,000x times more effective at setting your internal clock than, say, compared to early in the day in darkness.
Sunset
Viewing sunlight at low solar angle near sunset signals the central circadian clock that it’s the end of the day.
There is a study that shows that viewing sunlight around the time of sunset prevents some of the bad effects of light in preventing melatonin release later that same night.
- This is a protective system
- 2-10 minutes
How Do You Know if You Had Enough Sunlight?
You will know because your circadian rhythm will fall into some degree of normalcy:
- waking up more or less the same time each day
- fall asleep more easily at night
It generally takes about 2-3 days for these systems to align.
Bad Effects of Light
Due to artificial light from screens, we have access to light at night.
Because you become more sensitive to light the longer you are awake, smaller amounts of light, even the poor quality artificial light, can trigger the activation of the clock and disrupt your sleep pattern.
Danger
Avoid viewing light between 11 pm and 4 am!
Why?
- suppresses the release of dopamine and can inhibit learning
- Many other bad effects
How?
- Light through the eyes sends a signal to the habenula
- When the habenula gets activated, it makes us feel less happy and more disappointed
- also called the disappointment nucleus
How to reduce this bad effect of light exposure at night?
- Red light does not trigger this signal, or neural pathway
- but must be specific type of infrared light
- Use red lights
- Position light physically low
- Dim lights
- Candle lights and fire do not trigger this pathway
Sleep Supplements
Magnesium threonate will help you fall asleep when taken 30-60 minutes before sleep.
Theanine (100-200 mg) also helps fall asleep
- can cause very vivid dreams
- amplifies sleep walking
Taken together can be too much and cause too much sleepiness and difficulty walking up.
Apigenin (50 mg) can help support the creation of sleepiness to help fall asleep and stay asleep.
- potent estrogen inhibitor