It's all about the clock—internal and external
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June 24, 2020 9:40 AM EDT

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 minute staring 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.

“There is a risk for a breakdown in the biological clock,” says Dr. David Neubauer, associate professor at the Johns Hopkins University School of Medicine and a faculty member at the school’s Sleep Disorders Center. “Maybe you’re staying up later, eating regular meals in the evening but snacking or napping during the day. We have had people in whom circadian rhythmicity disintegrates.”

And those are people in the best and most enviable work situations. People who are out of a job are likely to suffer profound anxiety over finances and the future that working people don’t. Others, like those on the front lines of the pandemic—working in hospitals or at other essential jobs—now define their lives by little but work, which takes its own toll. “It’s incredibly stressful,” Neubauer says.” They’re working with patients who are in extreme conditions or are dying. They’re working long shifts. When they come home it’s difficult to relax and drift off to sleep.”

In either case, this can lead to what sleep researchers call “acute insomnia,” an inability to relax and fall asleep due to a “precipitate stressor.”

“There is depression, loneliness, anxiety and all of that undermines the ability to sleep,” Neubauer says.

Other kinds of anxiety cut across employment lines. No one is completely safe from COVID-19. Virtually everyone knows what it means to wear a mask, to socially distance, to randomly cough or sneeze and wonder if it is the first sign of a deadly disease. That chronic stress takes its own toll. Neubauer reports people having anxiety dreams in which they’re not wearing a mask when they should, or are getting too close to other people when they shouldn’t.

Other factors that mess with our sleep are more within our control, especially our media diets—both what we’re consuming and how we’re consuming it. The news has been all bad—or at least all distressing—lately, involving the coronavirus itself; police killings, systemic racism and the uprisings to protest the inequities; and the usual partisan mud fights over the economy and other issues. Gorge on that all day and you go to bed stuffed and anxious. When it comes to news then, less is more. “We can get a good update in five minutes,” Neubauer recommends. “We don’t need five hours.”

The news delivery system also matters. We use phones, tablets and computers all day, and then carry them right into our beds at night. That exposes us to both overstimulating information and to blue-wavelength light that is thought to suppress the sleep-inducing hormone melatonin (though some research has called that widely accepted wisdom into question). Either way, if your screen is the last thing you see before you turn out the lights, you’re probably not doing your sleep any favors. “I have people put their phones to bed at least one hour before they go to sleep,” Goldstein says. “It’s a hard cutoff from both the information and the light.”

Consistency matters too. Goldstein recommends that even if work does not require us to be up at a certain hour, we try to set an alarm for 8:00 AM—or another fixed but early hour—to align our circadian cycles better with the sun. And if at all possible, no napping if you fall out of alignment; that just scrambles the homeostatic system.

Sleep, which is easily the most passive thing we do, ought not be a thing that requires so much work. And under ideal circumstances it doesn’t. But the current circumstances are not remotely ideal—awful for some, at the very least stressful for everyone else. We can’t control the pandemic; we can control our response to it. Improving our sleep might be one of the healthiest responses of all.

Write to Jeffrey Kluger at jeffrey.kluger@time.com.

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