To celebrate World Sleep Day, here's our science-based guide to getting the best slumber you can – from varying sleep with the seasons to taking inspiration from the past.

It's a typical weekday morning, and you're just beginning to stir in bed. There's light streaking through the windows, while the many chirps and caws of birds announce that it's probably time to get up… but surely that can't be right? Cue the familiar feeling of dread, as you remember a night filled with restless, low-quality sleep.

Across the world, people are struggling with insufficient sleep. In the US alone, it's been estimated that between 50 and 70 million people suffer from the affliction, and on a global scale, it has even been called an epidemic. However, there are some simple adjustments – both psychological and physical – that might help to improve the quality of your sleep. Here's our guide to having a delicious, restful slumber, inspired by the latest scientific research and some long-forgotten historical tricks.

Slumber in two shifts

Today, when people wake up in the middle of the night, it's not unusual to panic – after all, we tend to believe that we should sleep for a continuous eight hours. But this has not always been the case. For millennia, people had a short first sleep – and then they woke up. These little slumber-gaps were filled with an endless variety of activities, from household chores to gossip in the dark (and even the occasional murder). Then after a couple of hours, people went back to bed and slept through until the morning.

This is the forgotten ancient practise of "two sleeps". It was rediscovered by Roger Ekirch, a university distinguished professor of history at Virginia Tech, Virginia, in the 1990s. He believes that an awareness of the habit's historical prevalence might help to reframe the experiences of those who suffer from insomnia today – and perhaps lessen their anxiety about waking up in the night. Read more about the lost ancient habit of "biphasic sleep" in this article by Zaria Gorvett.

Vary your sleep with the seasons

As spring arrives, you might notice that you need less sleep and are finding it easier to leave your bed in the morning. Research shows that we need more sleep during the dark, cold winter months than we do during the summer. This is because humans experience seasonal sleep. According to one German study, people experienced both longer REM and deep sleep in December than in June. REM sleep is the most active stage of sleep, when we dream and our heart rate increases, while deep sleep is when the body repairs muscle and tissues and is important for the consolidation of long-term memory. Read more about the seasonality of human sleep in this article by Isabelle Gerretsen.

Try a nap

In many countries having a catnap is a daily ritual, and research shows that regular naps are good for our health. According to a 2023 study, habitual napping helps keep our brains bigger for longer and can delay brain ageing by between three to six years. A smaller brain volume has been linked to diseases such as Alzheimer's and vascular dementia.

There are also short-term benefits. Short naps, lasting no longer than 15 minutes, can immediately improve how well we perform mentally, with results lasting up to three hours after we wake up. The key to power naps is to keep them short (after 20 minutes we start drifting into deep sleep) and to make sure you have one mid-afternoon so that it doesn't disrupt your sleep at night.

Beware the danger of microsleeps

But not all naps are good for us. Some last mere seconds and these microsleeps can result in serious harm if they occur when you're driving. Analysis of dashcam footage from 52 drivers from a single truck company in Japan found that three quarters of them showed signs of microsleep before they were involved in a collision.

Microsleeps are more common among people who suffer from narcolepsy or people who don't get enough sleep at night. One study found that when people slept for just six hours a night for 14 days in a row, they had as many microsleeps as those who missed a whole night's sleep. If you're regularly experiencing microsleeps, it's therefore probably a sign that you're not getting enough sleep generally. Read more about the naps that only last a few seconds in this article by Claudia Hammond.

Get cosy and cuddle up

As we snuggle up in bed for the night – particularly if it's just with a good podcast – we might wonder why it's so cold under the covers, or even a bit lonely.

Historically, having your own bed was highly unusual. Like it or not, most people had to share – and not just with their siblings in childhood, or as a married couple. Until the 19th Century, the majority of people would have slept communally, routinely slumbering alongside friends, colleagues and even total strangers. A good bedfellow would provide warmth and conversation into the early hours of the morning – though you might have to overlook their morning breath and contribution to a bedful of biting parasites. Read more about the forgotten habit of communal sleep in this article by Zaria Gorvett.

Aim for quality over quantity

How much sleep we all need can vary from person to person, with most recommendations for between seven and nine hours. But the amount of sleep you get is only one part of the equation. Quality matters as much, if not more.

Most of us will have experienced feeling less refreshed after a night of tossing and turning. That's partly because when we sleep, our brains flood with cerebrospinal fluid to clear out accumulated debris and toxins. This waste-clearance system is called the glymphatic system, which works best at the same time every day. This means that when we get our shuteye is important. Syncing sleep with our natural circadian rhythms – the brain's 24-hour internal clock that regulates the cycle of alertness and sleepiness – gives rise to the best-quality rest. Read more about the importance of sleep quality in this feature by Sandy Ong.

Be thankful for modern beds

Today most people in the Western world are lucky enough to wake up on a soft bed, perhaps with a spring mattress or memory foam. However, things have not always been so comfortable.

In the medieval era, many people opened their eyes each morning to stuffy air and pitch-blackness – the conditions inside a “box bed”. These popular sleeping-cupboards were completely enclosed, and helped to keep people warm at night, though they were sometimes not much bigger than a wardrobe. Slightly later there came the “tick” mattress, a bag of cheap materials such as straw or leaves. Unfortunately, they also provided the ideal hiding place for ticks, fleas and bedbugs. But the true inventors of a bad night's sleep might arguably have been the Victorians, who created a variety of unpleasant solutions for homeless people, from rows of coffin-beds to a rope to hang oneself over for a rest. Read more about the curious history of beds through the centuries, or top up your knowledge on why medieval people slept in cupboards, in these articles by Zaria Gorvett.

So, find yourself some bedfellows, allow for more sleep in the winter, and if you occasionally wake up in the night, consider yourself a modern pioneer of the lost ancient habit of biphasic sleep. We still can't promise that you'll be leaping out of bed on a Monday morning, but it's a start. (BBC)

Update news