A drop in temperature of 1-3 degrees is required for your body to enter a state of sleep, and a rise of 1-3 degrees will wake you up.
Caffeine can limit sleepiness by preventing the actions of adenosine.
Cortisol, which enhances your immune system, metabolism, ability to focus, and ability to move your body, should peak at the time you wake up, which can be achieved by viewing bright sunlight within 30-60 minutes of waking.
Artificial light cannot replace sunlight when trying to activate the cortisol mechanism, and can even disrupt sleep at night.
The morning sunlight dose should be about 5 minutes of sunlight exposure to the eyes per day on a clear day, 10 minutes on a cloudy day, and 20-30 minutes on a densely overcast or minimal sun day.
To leverage temperature for wakefulness, take a cold shower or ice bath for 1-3 minutes to increase core body temperature quickly, or exercise early in the day.
If you workout in the afternoon, take a hot shower or bath after exercise to decrease body temperature and help prepare your body for sleep.
Delay caffeine intake for 90-120 minutes after waking to avoid the afternoon crash, and avoid drinking caffeine after 4 pm.
The goal should be to view sunlight first thing in the morning 80% of the time, and if you miss a day, get twice as much duration of light the next day.
You can measure sunlight using apps like Light Meter on the App Store or Google Play.
