COVID-19 and its associated quarantine have messed with pretty much every aspect of our lives. Work time, meal time, family time, play time; our moods, our stress level, our tolerance; our ability to spend so much as one more minutestaring at the same four walls of the same den or living room or home office in which we spend most of our days.
And if you’re like plenty of people, the quarantine has also completely bollixed up your sleep cycle, wrecking what might have been the most predictable and peaceful eight hours of your day. Unless, that is, you’re like plenty of other people—and the quarantine has led to some of the best and most consistently restful sleep you’ve ever had. If the pandemic itself has been an unalloyed bad, its impact on sleep has been much more ambiguous.
“There are both upsides and downsides,” says Dr. Cathy Goldstein, associate professor of neurology at the University of Michigan Sleep Disorders Center. “We have more time in general so we’re devoting more of it to sleeping. When people run out of discretionary time, the first thing they do is condense their sleep. Now we can get that full eight hours—but we can also get too much.” At the same time, she points out, the pandemic might be causing other people to get too little sleep, or at times none at all.
Broadly, Goldstein explains, sleep is governed by two systems: the homeostatic and the circadian. The homeostatic system is more internal and is simply a function of how much sleep you’ve had and when you need more. The circadian system is pegged more to the external—the 24-hour clock and the daylight-nighttime cycle. “The two systems are independent but interlocking,” Goldstein says.
Left to ourselves, with no external clock but the rising and setting of the sun—humans in the state of nature in other words—we would all fall naturally into an approximate midnight to 8:00 AM sleep cycle, with 4:00 AM the peak and midpoint of rest. Those times are not fixed, of course, with the entire eight-hour cycle shifting earlier during the summer, when the sun might rise before 6:00 AM. Ten to midnight seems like a relatively late bedtime, but in that same state of nature there were also evening matters to tend to: getting children fed and put to sleep, tending the fires, watching out for predators. Indeed, Goldstein says, it’s normal for all of us to have a burst of evening alertness from 7:00 to 9:00 PM, which is more or less when our long-ago ancestors would have been performing these chores.
During quarantine, it appears that a lot of people are finding their way back to that primordial sleep state. In two papers currently in pre-publication for the journal Current Biology—one a study of 435 European respondents, and the other of 139 students at the University of Colorado, Boulder—researchers had only good news to report.
“They found the subjects were sleeping slightly longer and at more consistent times across the course of the week,” Goldstein says. “They found a reduction in ‘social jet lag,’ which is the deviation from the midnight to 8:00 AM natural cycle. The discrepancy is much reduced—with subjects sleeping more consistently across seven days.”
But things are also more complicated—and less rosy—than that. People with jobs that allow them to work from home may be less physically active than they normally would be, which can disrupt the homeostatic system; they may have less exposure to outdoor light and dark, which can disrupt the circadian system. They may be eating more or at irregular times, which can put the digestive and sleep cycles in opposition to each other.