For many people, the pandemic has completely changed the morning routine. No more running to catch the subway or racing to get to campus. So we’re sleeping in. According to one study out of the University of Colorado Boulder, students attending class remotely slept an average of 30 minutes longer during the week, and 24 minutes longer on the weekend, than they had during the regular pre-pandemic semester. They also shifted their wake times, getting out of bed nearly an hour later on school days. And it’s not just American students who have been spending more time snoozing; other studies found that during early lockdowns in Argentina and Europe, people slept longer and woke up later.

Céline Vetter, one of the authors of the Colorado study, says it’s hard to conclude from this data whether the pandemic has been good for our sleep habits, but it has revealed something else that’s important. “What it really says is that work is really a powerful determinant of our sleep behavior,” says Vetter, who directs the university’s Circadian and Sleep Epidemiology Lab. In other words, work schedules fundamentally change how and when people sleep, often causing them to sleep less—and rise earlier—than they would if they were just following their own circadian rhythm.

Now, as more businesses and schools are transitioning back to normal routines, some scientists argue that we shouldn’t necessarily return to the way things were in January 2020. Instead, we should consider the growing body of evidence that suggests that scheduling the workday to optimize sleep cycles would be better for people’s physical and psychological health. The results could stretch far beyond improved productivity. “When we think about optimizing sleep and aligning circadian rhythms with work hours, this is not only to optimize work,” says Vetter. “It is also to optimize life.”

The circadian rhythm is the natural process that regulates being asleep and awake. It’s a complex dance between genetics, hormones, and external factors like light and noise. Humans are diurnal creatures, meant to be awake during the day and to wind down at night. When we don’t get enough sleep, mistakes happen. Sleep deprivation can increase the likelihood of medical errors and car crashes. It can also make it harder to process emotional information or be empathetic. Working against that diurnal cycle can be bad for physical health too; it increases the risk of developing cardiovascular disease, type 2 diabetes, and colorectal cancer.

Some of the sleep cycle is influenced by external conditions. Sunlight cues the body to wake up, so being in a room with blackout curtains makes it much harder to wake up than if you were in a room where light streams in at dawn. Similarly, when it’s time to go to bed, dimming the house helps your body understand it’s time to rest.

Human behaviors matter too. Eating late at night or being on screens tells your body that it’s time to be active, which can counteract the effect of even the darkest room. And the longer we are awake, the more our need for sleep will build, creating what’s called homeostatic pressure, which is only relieved by finally getting some shut-eye. So pulling an extra shift means you might be ready for a nap in the middle of the day, even though the sun is out.

And finally, some sleep traits are genetically inherited. For example, thanks to a DNA fluke, some people need much less—or much more—than the average seven to nine hours every night.

A person’s genetic sleep traits combine to create a chronotype. An “early chronotype” is essentially a morning person, eager to wake up with the sun and head to bed early, while a “late chronotype” wants to stay up into the night and wake up later. People’s sleep hours range widely: One study found that in the United States they vary by nearly 10 hours. That means that a 9 am work start time could be a very different biological reality for some workers. “If you’re an early chronotype, this could be towards the middle of your day,” says Vetter. But for someone else, 9 am could still be their biological night.

For example, a recent study of police officers in Quebec by researchers in the Netherlands and Canada showed that people with different chronotypes had divergent reactions to working morning, evening, and overnight shifts. Early chronotypes adapted better to day shifts and slept more overall when they had early schedules. Conversely, officers who were late chronotypes lost sleep when they had to come in early, but slept more hours overall than their early-bird colleagues when they had later shifts.

Diane Boivin, a professor of psychiatry at McGill University and a coauthor on the study, says these findings show that one's chronotype is heavily influenced by genetics. But, she points out, there’s a limit to the role that genes can play, even for people who love to burn the midnight oil. “Even though you can find individuals who are extreme evening types and even describe themselves as night owls, we’re never night owls to the point that we become nocturnal animals,” she says. For the roughly 25 percent of the US workforce that does shift work—jobs like nursing, manufacturing, or hospitality—pulling the graveyard shift is likely to be tough. “It’s a minority of workers who do adapt,” says Boivin.

But for jobs that once required a more typical 9-to-5, maybe it’s the workplace that can adapt. Boivin says that the growth of teleworking, especially during the pandemic, could help give workers more scheduling choices. She’s already experimenting with this. Bovin directs the Centre for Study and Treatment of Circadian Rhythms at Douglas Mental Health University Institute, and her lab offers flexible hours to students and trainees. While everyone has to be present in the lab from 10 am to 4 pm to encourage teamwork, they are free to come in earlier or to work later. “In the ideal world, we would try to match a work schedule to an individual’s biological pattern, but it’s not always feasible. There needs to be times of interaction, so you have to set some boundaries,” Boivin says. (Even for her chronotype-aware laboratory, scheduling around sleep cycles isn’t always possible. Some experiments need to be monitored 24 hours a day, which means night shifts.)

Chris Barnes, a professor at the University of Washington who studies how sleep affects workers, says that in order for flex-time schedules to work, companies also need to make some cultural changes about how they treat sleep. “There are stereotypes around work schedules,” he says. His research suggests that people who choose to start their day earlier are seen as more productive and conscientious than their night-owl counterparts. If we don’t change those assumptions, employees won’t be willing to take advantage of solutions that allow them to start work later. And Boivin points out that even in a workplace that allows flex-time, some workers may favor other exigencies, like time with their families, over their sleep needs.

Barnes suggests that nap pods or rooms could also help employees rest. “Rather than seeing a nap at work as loafing, we should instead think of it as an investment,” he says. Fifteen minutes of downtime could help people be more creative, efficient and productive—but people have to be comfortable with taking that option. Barnes says company leaders should be seen using those nap rooms, and they should talk about how important it is to be well rested at work. Instead of sending emails at 2 am and expecting an immediate response—or instead of praising employees who are seen in the office very early or working late—managers should reiterate that sleep is a priority.

Ultimately, the pressure to get up early, to work long hours, and the idea that work is more important than sleep is more social than biological. Just because traditional schedules have prioritized the 9-to-5 slog doesn’t mean that’s the best for everyone. Studies of high school start times show that when schools start later, allowing teenagers a few more hours of sleep, students get better grades, have better attendance, and do better on standardized tests.

“Circadian rhythms are fundamentally physiological processes, so we can’t just wish them away,” says Barnes.

Instead, these researchers suggest that people figure out their chronotype, practice good sleep hygiene—dimming the house, getting off of screens, having a consistent bedtime—and stop judging themselves and others for their sleep differences. “Nothing is better than the other,” Vetter says. “There’s a range, and that’s fine.”