This is Expert Habits, a regular column in which thinkers, leaders, and other high performers talk about the habits and routines that help them live a better life.
Why do we sleep? Dr. Matthew Walker, a podcaster, sleep technology entrepreneur, and professor of neuroscience and biomedical Engineering at UT Dallas wrote a 2017 bestselling pop-sci book that answers that very question.
“Twenty years ago, the crass answer was: ‘Well, you sleep to cure sleepiness,’ which is the stupid equivalent of saying, ‘well, you eat to cure hunger,’” says Dr. Walker. “No, you don’t eat to cure hunger. You eat for all sorts of physiological reasons.”
The same, he says, goes for sleep. Per Walker, who has studied brain performance and sleep innovation for the past two decades, everything from our appetite to cardiovascular dynamics like blood pressure is adversely impacted by a lack of proper sleep. Studies have shown, for example, that men who consistently sleep five hours or less a night even have significantly lower levels of testosterone, which in turn ages their reproductive capabilities. Even more concerning: Almost a third of adults in the US get below the recommended amount of sleep (at least seven hours) every night, according to the Center for Disease Control.
Despite the wealth of knowledge Dr. Walker has struggled with getting enough rest, too.“Just because you know a lot about sleep does not mean that you are immune to the vagaries of things like insomnia,” he says. “And I’ve probably had two significant bouts of insomnia in my lifetime. The fortunate thing is that I know I have all of the tools to course-correct it very quickly.”
Below Dr. Walker details the importance of his nighttime mood lighting, why he always puts his hands in warm water before bed, and why he maintains a consistent sleep schedule. “Regularity is king,” he says.
Set a “to-bed” alarm an hour before bed
“You already keep an alarm that decides when you get up. Notice what’s missing: Nothing decides when you go to sleep. Wake-up is guarded. Bedtime is the most undefended border in your day, and everything raids it. One more email. One more episode. One more scroll. The hour you meant to protect gets annexed 10 minutes at a time, until it’s gone. The to-bed alarm is the border guard.
“But the deeper reason lives in the architecture of sleep itself. Falling asleep is not a switch you flip. It’s a descent. A plane doesn’t drop from thirty-five thousand feet onto the runway in one second—it begins its approach long before the wheels touch, throttling down, losing altitude in a slow, deliberate glide. Your brain does the same thing (or should do the same thing, but many of us in society believe sleep is like a light switch). Core temperature has to fall. The alerting signal your body clock has broadcast since morning finally has to go quiet. None of it happens on command.
“So when the alarm sounds an hour before lights-out, it isn’t telling you to sleep. It’s telling you to start your descent—handing back the 60 minutes you need to throttle down, at the same time every night. You can’t land a plane you never started descending.”
Conduct a nightly digital detox
“Even if it’s 30 minutes before bed, or even just 15 minutes. Some kind of disengagement and a blast radius distance between you stopping your engagement with digital technology and trying to fall asleep is going to be better. And the further the distance between those two things, typically the greater the efficacy. So the dose and the timing make the medicine.