Shift workers, new parents, students cramming during exam period — sometimes life circumstances just don’t allow for getting a solid eight hours of sleep every night. You may find yourself grabbing sleep whenever you can.

But does that provide the reset your brain and body needs?

What Is Segmented Sleep?

Segmented sleep is when you break up your sleep into two or more shifts with periods of being awake in between, according to Michelle Drerup, PsyD, a psychologist and director of the Behavioral Sleep Medicine Program at the Cleveland Clinic. It may look like sleeping for four or five hours at night before heading to an early morning shift at work, then taking a two or three hour nap during the day, Dr. Drerup says.

Segmented sleep is also known as biphasic sleep or polyphasic sleep, the Sleep Foundation notes. Biphasic sleep refers to sleeping in two phases while polyphasic sleep breaks bedrest down into several segments. That’s opposed to monophasic sleep, which is the conventional way we approach sleeping in a single block of time overnight.

Segmented sleep has roots dating back to ancient civilization and was common through the early 19th century. Roger Ekirch, PhD, a University Distinguished Professor of history at Virginia Tech in Blacksburg, who’s studied segmented sleep, has said research shows earlier generations had a first sleep just after dusk, followed by a few hours awake. Then they’d head back to bed for a second sleep that lasted until morning.

“It was our natural human sleep pattern,” says John Cline, PhD, a licensed clinical psychologist specializing in sleep medicine and a diplomate of the American Board of Sleep Medicine who is based in Cheshire, Connecticut. It wasn’t until we had clocks, artificial light and the start of the Industrial Revolution that people began forcing themselves to sleep through the night, Dr. Cline says.

In some cultures, segmented sleep — in some shape or form — still exists. Think of siesta time in Spain or Italy, where people retire to their homes for an afternoon nap before heading back to work.

Is Segmented Sleep Healthy?

While segmented sleep may have worked for our ancestors, breaking slumber down into two or more chunks isn’t healthy, practical or sustainable, in today’s society, says Colleen Carney, PhD, an associate professor and director of the Sleep and Depression Laboratory at Toronto Metropolitan University.

Our bodies rely on deep sleep every night for restoration, physical recovery, memory consolidation, and even bolstering the immune system, according to the National Heart, Lung, and Blood Institute (NHLBI). “But if people are sleeping multiple times during the day, they’re never building up enough deep sleep to get to that. You aren’t getting the type of sleep architecture that you want,” Dr. Carney says.

We cycle through four stages of sleep while we’re slumbering — ideally, we should be getting as much of stage 3 non-REM deep sleep we can get to provide our bodies with a proper reset for the next day.

Carney notes that the timing of your sleep is important too. Our bodies follow a circadian rhythm — a 24-hour cycle that’s running internally, influencing when we’re alert, sleepy and even hungry. When you try to sleep during the daytime, your body is fighting against cues to stay awake and deep sleep may be harder to attain.

Drerup suggests segmented sleep is unsustainable, and may even lead to sleep deprivation. She points to a study published in 2017 in the journal Scientific Reports that followed 61 university students, analyzing their sleep habits and their academic performance. The researchers found that students who followed irregular, segmented sleep schedules had disruptions to their circadian rhythms equivalent to traveling west by two to three time zones. They also had lower grades compared with their peers who had a steady single block of sleep — even if both sets of students slept the same number of hours.

Drerup says segmented sleep schedules tend to reduce your overall number of hours of sleep, which can lead to sleep deprivation. The NHLBI warns that this can put you at risk of high blood pressure, depression and anxiety, heart disease, diabetes and obesity.

“There is no evidence that segmented sleep is linked to any physiological benefits,” Drerup says.

Tips for Segmented Sleep

If you must follow a segmented sleep schedule because of work, home life or other responsibilities, the experts say there are a few rules to follow:

Aim for 8 Hours of Rest — in as Lengthy Blocks as Possible

Make sure to get close to eight hours of sleep in a 24-hour period, Drerup says.

If you previously slept for seven or eight hours per night but now you can only get five hours with your newborn’s waking and feeding times, try a schedule that consists of one nighttime block and two or three two-hour naps when your baby is asleep in the daytime, she suggests.

Be Consistent

Once you’ve carved out a segmented sleep schedule that works for you, stick to it, Cline says. “If you’re going to adopt a pattern like this, you can’t switch back and forth every couple of days. That would scramble your circadian rhythm,” he says.

Try to Get Nighttime Sleep (or at Least Mimic it)

Because our bodies are hardwired to relax and rest at night, you may struggle to fall asleep and stay asleep in the daytime when your internal clock is telling you to wake up, Cline says.

If your schedule permits, try to get the majority of your slumber overnight when your body is craving rest most.

During the day, follow sleep hygiene strategies that bring you closest to a nighttime atmosphere. The Sleep Foundation suggests using blackout curtains to block out sunlight, and wearing earplugs to drown out noise around your home.

Don’t Nap Too Close to Bedtime

If you’re planning on going to bed at night, try not to nap after about 7 p.m., Carney says. She calls this the “Forbidden Zone,” where an early evening nap would wipe out the sleep drive you’ve built up during the day.

You’re better off napping in the early morning or afternoon. This way, you’ll feel more tired and ready for a snooze when nighttime rolls around.

The Sleep Foundation recommends talking with your doctor before you try segmented sleep so you can make a plan that works for you and doesn’t harm your health.

Additional reporting by Alice Martin.