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In the first half of the day, dopamine and norepinephrine are elevated in the brain, body, and bloodstream much more than serotonin. This affects our perception of time and suggests we should tackle the hardest tasks early in the day.

You can't cheat the circuits related to acetylcholine and dopamine; after about 90 minutes, focus diminishes.

Sleep is the best performance enhancing drug in the whole world. It's the thing you want to do every night.

Altradian rhythms, about 90 minutes long, govern our ability to focus and engage in mental or physical work.

The single best thing I've learned out of everything I've ever done is your resting heart rate before sleep is the best thing you can do for your health. Hands down.

If you have a cup of coffee at 4 p.m., at bedtime, a half a cup of coffee is in your system.

Did you know if you don't sleep, your prefrontal cortex goes offline and you lose your willpower? So when you're trying to not eat the cookie, you're powerless. You can't do it. It's gone.

Light seen by your eyes inhibits melatonin, which makes you sleepy and regulates hormones like testosterone and estrogen.

You need to turn your screens off an hour before bed. That one hour is so important because you have to give your body the ability to wind down. And if you're scrolling or working, you're going to be in a roused state, which boosts your heart rate.

Disruptions in circadian entrainment cause huge health problems, increasing cancer risk, obesity, and mental health issues.