[Huberman Lab Podcast笔记-睡眠]

Factors affecting our sleep quality

• Adenosine
  Sleepiness is driven by increase of adenosine that happen naturally. Caffeine acts as a adenosine antagonist by blocking its receptor. Rather than demonize caffeine, or saying everyone can drink caffeine until late, you need to figure out what's right for you.

• Circadian force
  Our sleep and our period of sleepiness tends to be condensed into one block, typically one 6 to10 hour block. That block of sleep and when it falls within into each 24 hour cycle is governed by a number of different things. The most powerful things is light, particularly sunlight.

Hormones

• Cortisol
  Alert your whole system in your body when you wake up, it's important the pulse of cortisol comes early in the day and happens all at once.

• Melatonin
  Only released from pineal. Suppress the other hormone which triggers the onset of puberty. Not recommended to take melatonin supplement, the dose may be actually 50% to 400% of what is says on the bottle.

Time the cortisol pulse
The cells respond better to sunlight at low solar angle. Get sunlight in your eyes as close to waking as possible. If you can watch the sunrise, great, however if you wake up a few hours after the sunrise, you still want to get outside to view the sunlight. It's critically important you get outside to get these light. It's 50 times less effective to view the sunlight through the window, car windshield or a side window of a car. Once the sun is overhead, the quality of light shifts and you miss the opportunity to time the cortisol pulse. You really want to time that cortisol pulse properly. Because a late shifted cortisol pulse, in particular a 9pm, 8pm increasing cortisol is one of the consequence or maybe causes of depression and anxiety. 2 to 10 minutes of sunlight exposure is gonna work. If you cannot get sunlight, you can get artificial light especially blue light.

Sunset
Viewing sunlight during sunset prevents the negative effect light does to your body later.
Having those two signals arriving to your central clock, that your body your internal world knows when its morning and knows when its evening, is tremendously powerful.

Bad light
You want as much light as is safely possible early in the day, morning and throughout the day including blue light unless you have real issue with screen light sensitivity, you want as little light coming in your eyes, artificial or sunlight after say 8pm. Certainly you do not want to get bright light exposure to your eyes between 11pm to 4am. Study shows light arrives to the eyes betweem 11pm to 4am approximately suppress the release of dopamine, this neuromodulator that makes us feel good, and can inhibit learning and create all sorts of detrimental effects.

Light location
Dim light low in your physical environment is the best.

How to wake up early
Lights before you wake up make you sleep more and wake up early, want to go to bed early. It will advance your clock. You don't want to get too much exposure late in the evening.