Why Modern Homes Make It Harder to Sleep (and 7 Ways to Cool Your Bedr

You fall asleep as your body cools down, and many modern homes, heated and insulated to hold one steady temperature all night, give it little chance to. A recent BNR report points to new research suggesting that falling air temperature may shape our sleep rhythm at least as much as light does. The evidence in people is still early, but acting on it is low-risk: let your bedroom cool at night (roughly 16 to 20°C suits most adults), keep your hands and feet comfortable, and sleep under bedding that lets heat and moisture escape. Below, we explain what the research does and does not show, then give seven simple steps.

Does room temperature affect sleep as much as light?
Why do modern homes make it harder to sleep?
What temperature should a bedroom be at night?
1. Turn the heating down in the bedroom
2. Let fresh air in before bed
3. Take a warm bath or shower first
4. Keep your hands and feet warm
5. Sleep under bedding that breathes
6. If you share a bed, don't settle for one temperature
7. Don't forget light and routine
FAQ
Sources

Does room temperature affect sleep as much as light?

For years, the textbook answer was that light is the main signal that sets our body clock. The BNR report says that view is being challenged by studies of communities that live without electric light or central heating.

The best-known example is a 2015 study by Gandhi Yetish, Jerome Siegel and colleagues. It tracked sleep in three communities without electricity: the Hadza in Tanzania, the San in Namibia and the Tsimane in Bolivia. Sleep started on average about three hours after sunset, during a period of falling air temperature, and people tended to wake close to the daily temperature low. The authors suggested that ambient temperature "might be a major determinant of sleep timing and duration, independent of light level". The Tsimane and San also reported far less chronic insomnia than the 10 to 30% seen in industrial societies.

BBC reporting, carried by bdnews24, adds that core body temperature falls about 1°C overnight, and that people in a bedroom that cooled and warmed naturally had higher melatonin levels and felt more refreshed than people in a room held at a constant temperature.

It is worth being straight about the limits. The BBC describes the human evidence as "limited but suggestive", and chronobiologist Christian Cajochen of the University of Basel says far more research is needed before temperature can be put on a par with light. Here is how we weigh up the main claims:

Claim	Where it comes from	How sure are we?
Sleep starts as the air cools in communities without electric light	Hadza, San and Tsimane study (Yetish et al., 2015)	A clear pattern in small groups, but it shows a link, not proof of cause
Core body temperature falls overnight, and this goes with sleep	Basic sleep physiology (Sleep Foundation, BBC)	Well established
A bedroom that cools naturally beats a constant-temperature one	Small human experiments reported by the BBC	Early: "limited but suggestive"
Constant-temperature homes help explain high insomnia rates	A hypothesis put forward by Jerome Siegel	Unproven

The honest summary: temperature probably matters, and whether it matters as much as light is still open. The good news is that testing it at home costs almost nothing.

Why do modern homes make it harder to sleep?

Insulation and central heating have made our homes more comfortable and cheaper to heat, but they also tend to hold a bedroom at one steady temperature, day and night, all year round. In the BBC's reporting, Siegel argues that homes kept at a constant temperature probably contribute to the high rates of insomnia in industrialised societies. That is a hypothesis, not a proven cause.

The mechanism is plausible, though. According to the Sleep Foundation, your core temperature starts to fall about two hours before you go to sleep and keeps dropping to a low point in the early morning. Your body does this partly by sending heat from the core out to your hands and feet. A warm, still bedroom and bedding that traps heat make that cooling harder.

Stress, caffeine and irregular hours matter too, but room temperature is one of the cheapest things to change.

What temperature should a bedroom be at night?

Most doctors recommend a bedroom temperature of about 15.6 to 20°C, according to the Sleep Foundation, with around 18°C often given as the sweet spot. It adds that the ideal can vary by a few degrees from person to person, and that a cold bedroom is not considered as harmful to sleep as an overly warm one, although it can be uncomfortable.

If your bedroom sits at 21 or 22°C overnight, try lowering it by a couple of degrees for a week and see how you feel. Here are seven steps that put the research into practice.

1. Turn the heating down in the bedroom

Turn the radiator down, or set your thermostat to drop in the evening, ideally to somewhere between 16 and 18°C if that feels comfortable. Lower rather than off is usually enough, and a cooler setting also uses less energy. The aim is a cool room, not a cold one.

2. Let fresh air in before bed

Opening a window for a while before bed lets warm, stale air out and cooler air in, and the Sleep Foundation recommends ventilating the bedroom. If you don't like sleeping with a window open, air the room beforehand and close it again. The same principle works in summer, as we explain in our guide to sleeping in a heatwave.

3. Take a warm bath or shower first

This sounds backwards, but it works with the same body-cooling process. A review of studies in Sleep Medicine Reviews found that a warm bath or shower one to two hours before bed helps people fall asleep more quickly, and it doesn't need to last longer than about 10 minutes. The likely explanation is that warm water draws blood to the skin, so you shed heat faster once you step out.

4. Keep your hands and feet warm

Because your body cools by releasing heat through your hands and feet, cold feet can get in the way. The Sleep Foundation notes that people with chronically cold feet may be at higher risk of trouble falling asleep. Warm socks or a hot-water bottle are worth a try. The evidence for bed socks specifically is thin, but it costs nothing to test.

5. Sleep under bedding that breathes

A cooler bedroom only works if your bed stays comfortably warm, and that is where bedding matters. Under your duvet you create your own little climate of body heat and moisture. Bedding that traps that moisture leaves you clammy and overheated, while bedding that absorbs and releases it keeps things steadier through the night.

Wool is a natural moisture manager. Woolmark, the wool industry body, says wool fibres can absorb up to 35% of their weight in moisture before feeling wet. That is one reason many people find a wool duvet comfortable in a cool bedroom without overheating. To be clear, wool won't cure insomnia, that figure comes from the industry, and good cotton or linen sheets help too. If you are lowering the bedroom temperature this autumn, a medium all-season weight is a sensible starting point. Our duvet buying guide and our comparison of wool, down and synthetic duvets explain how to choose.

Texeler Multi Choice Wool Duvet 400 g/m2, a medium all-season wool duvet

A medium weight to start with

Multi Choice Wool Duvet 400 g/m²

Texeler wool in a medium all-season weight, also available at 120, 200 and 600 g/m² so you can match it to your bedroom.

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6. If you share a bed, don't settle for one temperature

Because the ideal temperature varies from person to person, two people in one bed rarely agree. Rather than compromise, give each side what it needs: two separate duvets, or one built for it. Texeler's Satin Partner ZipSet gives each side its own warmth level, and the ZipSet range uses two wool layers you can separate or zip together as the weather changes. We ask whether that is worth it in our all-seasons duvet guide.

7. Don't forget light and routine

Even if temperature matters as much as light, light still matters. Get daylight in the morning, keep the lights low in the evening, and keep similar bed and wake times. Our sleep blueprint covers the rest of the routine.

A cool room and a comfortable bed

If you are cooling the bedroom this autumn, Texeler wool duvets come in several weights, from light summer layers to warm winter ones.

Browse wool duvets →

Texeler wool bedding from Texel Island, available at WarmWool.

Frequently asked questions

What is the best bedroom temperature for sleeping?

Most doctors recommend about 15.6 to 20°C, according to the Sleep Foundation, with around 18°C often cited as ideal. The best temperature can vary by a few degrees from person to person, so try somewhere between 16 and 19°C and adjust to what feels right for you.

Is it bad to sleep in a cold room?

A cold bedroom is generally considered less harmful to sleep than an overly warm one, but it can be uncomfortable. The aim is a cool room and a warm bed: lower the room temperature, but keep your bedding and your feet comfortable.

Does temperature matter more than light for sleep?

We don't know yet. The BNR report suggests temperature may matter at least as much as light, but the BBC describes the human evidence as limited but suggestive. Both are worth getting right, and neither is hard to do.

Does wool bedding help you sleep better?

Wool won't cure insomnia, and sleep depends on many things. What it can do is help manage the climate under your duvet: according to Woolmark, wool fibres can absorb up to 35% of their weight in moisture before feeling wet. Many people find that keeps them comfortable in a cool bedroom, but comfort is personal.

When should I see a doctor about poor sleep?

If you struggle to fall asleep or stay asleep for several weeks, or tiredness is affecting your daily life, speak to your GP. Persistent insomnia can have causes that bedroom changes won't fix.