Why We Sleep – and Why We Used to Do It Twice

Most of us don’t think too hard about sleep—until we’re lying wide-eyed at 2 a.m., counting sheep, ceiling tiles, or yesterday’s regrets. For folks who can nod off faster than a toddler in a car seat, sleep might seem as natural as breathing. But if you’ve ever tossed, turned, or wondered if waking up at 3 a.m. is just your new normal, you’re not alone. In fact, 1 in 3 people deal with some form of insomnia. That’s a lot of late-night snackers.

But did you know people didn’t always sleep in one long stretch at night? Once upon a time, sleeping in two shifts was totally normal. It’s called biphasic sleep—a fancy name for breaking your snooze into two parts. And it wasn’t weird. It was just… Tuesday.

Let’s curl up under the covers and take a dreamy stroll through the history of sleep, from Neolithic naps to modern memory foam.

Why We Snooze in the First Place

We sleep for the same reasons we eat vegetables and avoid touching hot stoves: because it’s good for us.

Sleep keeps your body and brain in tip-top shape. It’s when we:

• Process emotions (and awkward conversations).
• File away memories like a human hard drive.
• Repair cells and tissues.
• Give the ol’ immune system a boost.

Thanks to hormones like melatonin and adenosine, your body follows a 24-hour rhythm (called the circadian rhythm). It’s like your body’s internal bedtime playlist, signaling when it’s time to wind down.

But here's the twist: not all humans follow the same pattern. Some need more sleep, some less. Some conk out at 9 p.m., others scroll until the birds start chirping. And some—past and present—sleep in two parts.

Nap Like It’s 9000 BC: Neolithic Era Sleep

We don’t have sleep journals from the Stone Age, but researchers have peeked at present-day hunter-gatherer communities to get clues. A study by UCLA found that traditional societies tend to fall asleep about 3.5 hours after sunset and snooze for around 6.5 hours total. People slept more in the winter, less in the summer. And guess what? Biphasic sleep was probably totally normal. Think: nap on some soft grass, wake up to chase off a wolf, go back to sleep.

As civilizations advanced, sleep became a big deal—just ask the ancient Egyptians. They even worshipped sleep and designed fancy homes with actual beds. Clearly, they were onto something!

Double Trouble: Sleeping in the Middle Ages

Fast forward to the Middle Ages, where segmented sleep really took the spotlight. According to historian Roger Ekirch (check out At Day’s Close: Night in Times Past), folks didn’t just sleep—they had a first and second sleep. The first started a couple of hours after sunset, followed by a wakeful window of one to two hours, and then a second round of slumber.

What did people do in that midnight window? A little bit of everything:

• Prayed
• Read
• Chatted with family
• Visited neighbors (!)
• Hit the outhouse

They also slept as a family—literally all in one bed—to conserve warmth. Beds started getting fancier, too, with wooden frames, straw mattresses, and eventually, more padding. (Cozy, right?)

But by the late 1600s, references to segmented sleep started to disappear. By the 1920s, the idea of a first and second sleep was pretty much lost to history.

Electric Dreams: Industrial Revolution to Now

The 1800s rolled in with a bang—and lightbulbs. Thanks to the Industrial Revolution, bedtime got a makeover. Factory work, long hours, and the bright glow of electricity meant people no longer had time (or the dark) for a two-part sleep.

We started squeezing all our sleep into one stretch—what scientists call monophasic sleep. Social life shifted, too. Instead of one bed for the whole family, individual bedrooms became the norm. Goodbye, cuddling, hello personal space.

Also worth noting: this era brought us bedsprings, Murphy beds, and eventually, memory foam. Sleeping got more high-tech—and less segmented.

Should We Bring Back Biphasic Sleep?

So… should we go full medieval and split up our sleep again? The jury’s still out. There’s not enough research to say biphasic is better—or worse—than our current all-at-once approach. But here’s what we do know:

Some pros:

• Naps (even short ones) can improve memory, alertness, and mood.
• If you naturally wake up in the middle of the night, embracing it instead of stressing might help.
• It’s still common in Mediterranean and Muslim cultures—and it works for them.

Some cons:

• Not everyone’s schedule fits a two-part system. Work, kids, and life can get in the way.
• Trying to force segmented sleep might make you more tired.
• Chronic sleep loss is no joke—it’s linked to health risks like heart disease and anxiety.

Bottom line? Talk to your doctor before making big sleep changes. And don’t panic if you find yourself wide awake at 3 a.m. Maybe your body’s just getting medieval.

Tips for Sleeping Like a Champ (No Matter the Century)

Whatever your sleep style—monophasic, biphasic, or "whenever the toddler lets me"—these tips can help you catch better ZZZs:

• Stick to a regular bedtime and wake-up time.
• Keep your bedroom cool, quiet, and dark.
• Use your bed only for sleep (and, okay, maybe snuggling).
• Ditch screens 30–60 minutes before bed.
• Cut caffeine a few hours before bedtime.
• Create a relaxing bedtime routine (pajamas, anyone?). 

The Dreamiest Sleep Is the One That Works for You

We’re big fans of helping you drift off in the coziest way possible—whether that means snoring in matching pajamas or sipping chamomile tea in moose-printed joggers. If you’re struggling with your sleep, check out our other post on how to build a better sleep schedule. Sweet dreams, sleepyheads!