No one knows what a perfect night’s sleep actually looks like

The less you worry about your rest, the better it will be: That’s Jamie Zeitzer’s advice.

Jamie M. Zeitzer is a professor of psychiatry at Stanford University’s Center for Sleep Sciences. Here’s his tale from the field, as told to Claire Maldarelli.

As a sleep researcher, one of the most common questions I’m asked is how to get a better night’s rest. That’s a challenging inquiry to answer. Many of us in the field began studying the subject because we are so terrible at it in practice. And despite decades of study, we still don’t totally understand what sleep is—or why our ancestors first started doing it.

All vertebrates alive today have a form of slumber. So do some invertebrates like fruit flies and sea slugs. You can trace restfulness back to single-celled organisms that split their time between periods of quiescence and bursts of activity. In some ways, sleep is just a state of inactivity. But there’s something unique about it that we haven’t figured out.

Despite what our fitness trackers might tell us, we don’t yet know what mix of deep, light, and REM—the three stages of sleep—translates into the best rest. People obsess over these numbers, but they aren’t actionable.

With so much left to learn about the purpose of repose, it’s no wonder we can’t quantify it. Unfortunately, I’ve also found, in my research and personal habits, that most sleeping problems stick around. Once you’ve had trouble getting your z’s, you’ll be susceptible to that same issue again. The irony, of course, is that the less you worry about your rest, the better it will be. Given my profession, I sort of set myself up for failure there.

This story appeared in the Spring 2020, Origins issue of Popular Science.