Biphasic sleep: does splitting your sleep work?

Does biphasic sleep work?

Biphasic sleep means sleeping in two blocks every 24 hours. Most often that’s a night’s sleep plus an afternoon nap. Or it’s two sleeps at night with a gap.

It can work, as long as the total is enough. The NHS says adults need 7 to 9 hours on average. Splitting your sleep doesn’t shrink that number.

Constantly tired during the day? The NHS says you probably need more sleep, however you split it.

Your first move: add up both your sleeps each day for a week. A sleep diary makes this easy. If you’re under 7 hours on most days, fix the total before the timing.

What are the biphasic sleep schedules?

Neither study showed you can get by on less sleep in total. Polyphasic fans claim to thrive on as little as 2 hours a day. The panel found no evidence for that.

So pick a split that fits your day, not one that trims your sleep. Working nights? See sleep for shift workers.

What happens when you split the same hours?

A trial in Singapore gave 58 teens aged 15 to 19 the same 6.5 hours in bed for 5 nights. Half slept in one block. Half slept 5 hours at night and napped 1.5 hours in the afternoon.

That result was blood sugar. In a glucose test, you drink a sugary drink and then have your blood checked. The split group’s level rose more after the short-sleep nights.

Both groups still had more lapses in focus than teens in an earlier study given 9 hours in bed. The researchers advise teens to get the recommended amount of sleep at night.

This was a short trial in teenagers. It doesn’t tell us how adults respond, or whether the sugar rise leads to diabetes.

So treat a nap as a top-up, not a swap for night sleep. See how much sleep you need for your age.

Did people once have a first and second sleep?

Historian Roger Ekirch argues that most people in the pre-industrial western world once slept in two parts. He says one long sleep took over in the 1800s. Another historian has challenged this.

A lab study backs part of it. When people had only 10 hours of light a day, their sleep often split in two. They lay awake for 1 to 3 hours between.

But in three groups living without modern industry today, sleep wasn’t broken by long spells awake. They napped on fewer than 22% of summer days.

The NHS lists regularly waking several times a night, or lying awake, as signs of insomnia.

Awake for around 20 minutes? The NHS suggests you get up and sit somewhere comfortable. Read or listen to quiet music, and go back to bed when you feel sleepy.

Happens most nights? Read about CBT for insomnia. It’s a talking therapy that changes the thoughts and habits that keep you awake.

How long should a biphasic nap be?

In a study of 24 young adults after a 5-hour night, a 10-minute nap worked best overall.

That groggy spell is called sleep inertia. Here’s how to shake off grogginess.

Long naps are different. In data on over 150,000 people, naps of 60 minutes or more a day were linked to more heart disease and deaths. Shorter naps were not.

Linked means seen together, not proven to cause.

When to speak to a GP

Book an appointment if:

• Changing your sleep habits hasn’t helped, you’ve had trouble sleeping for months, or it makes daily life hard to cope with.
• Your breathing stops and starts in your sleep, you make gasping, snorting or choking noises, or you always feel very tired during the day. These can be signs of sleep apnoea, when your breathing stops and starts while you sleep. It can be serious if not treated.
• You fall asleep suddenly during the day, or you feel tired all the time for no reason.
• You often wake in the night, and it worries you or affects your life.

Has someone seen you stop breathing or gasp in your sleep? The NHS says it can help to bring them with you to the GP.