The best way to sleep when it's cold is to warm the bed, not the room. A cool bedroom of roughly 16–18°C with a warm duvet, warm feet and a pre-warmed bed is close to ideal for most adults. A bedroom heated to 22°C all night tends to produce the opposite problem: you fall asleep fine and wake at 3am sweating under a winter duvet.
So the aim on a cold night is to get the warmth against your body and leave the air cool. Here is how to do that in a UK home with radiators, a heating timer and a draughty window.
Cool room, warm bed
Your body needs to lose a little core heat to fall asleep, and it does that by sending warm blood to the skin, especially the hands and feet. Cold hands and feet block this. That is why it is hard to drop off when your feet are icy, even under a thick duvet, and why warming them is the single most effective fix.
Once you are asleep, what matters is the temperature in the small pocket of air under the covers. Research on the temperature dependence of sleep (Harding, Franks and Wisden, 2019) suggests that pocket needs to be comfortably warm while the air you breathe stays cool. A warm duvet in a cool room gives you exactly that. A warm room gives you a warm pocket that keeps getting warmer.
In short: Warm feet, warm bed, cool air. Heat the person, not the room.
Warm your feet first
- Bed socks. Loose, not tight at the ankle. Wool or a thick cotton blend. Many people take them off in the night once they are warm, which is fine.
- A warm foot bath or a shower before bed warms the extremities and, oddly, helps you cool down afterwards in the way that sleep needs.
- A hot water bottle at the foot of the bed, put in twenty minutes before you get in, so the bed is warm where your feet will be.
Use a hot water bottle safely
Hot water bottles are cheap and effective, and they cause a surprising number of burns. A few rules:
- Use hot tap water, not boiling. Boiling water degrades the rubber and can cause it to split.
- Fill it no more than two-thirds, expel the air, and check the stopper is tight.
- Always use a cover. Direct contact with skin for long periods can cause burns even at moderate temperatures.
- Replace it every couple of years, or sooner if the rubber is stiff or cracked. The flower symbol moulded on the neck shows the year of manufacture.
- Do not lie on it, and take it out of the bed before you fall asleep, or at least move it to the foot of the bed.
Electric blankets are an alternative for pre-warming the bed. Use one that is in good condition and carries a UK safety mark, follow the instructions about switching it off before you sleep unless it is designed for all-night use, and never use one with a hot water bottle. Electrical Safety First publishes guidance on checking older blankets.
Layer the bedding
UK duvets are rated in tog. A 13.5 tog duvet is the usual winter weight, 10.5 tog suits spring and autumn, and 4.5 tog is for summer. All-seasons duvets combine a 4.5 and a 9 tog that clip together for winter.
Layers beat one heavy duvet, because you can adjust in the night without getting up. A 10.5 tog duvet with a blanket or throw on top, which you can push off at 3am, is more flexible than a 15 tog duvet that leaves you no option. Wool and down insulate well for their weight; hollowfibre is cheaper and heavier for the same warmth.
Under you matters too. A lot of heat is lost downwards into the mattress. A mattress topper, a fleece underblanket or even a folded blanket under the sheet makes a cold bed feel much warmer. The bedding and duvet tog guide covers fills and fabrics in more depth.
For pyjamas, natural fibres or brushed cotton breathe better than fleece, which can leave you sweaty by the early hours. Pyjamas you can take off easily matter, because being able to shed a layer is the point.
Time the heating
Most UK heating runs on a timer, and the usual mistake is having it on until bedtime or through the night.
- Heating off an hour before bed. The house stays warm enough to get ready in, and the bedroom drifts down towards a good sleeping temperature as you wind down.
- Bedroom radiator lower than the rest. A thermostatic valve at 2 or 3 keeps the room from being cold without heating it to living-room levels.
- Morning heating on before you wake, not before you get up. Getting out of a warm bed into a cold room is the miserable part of winter; a room that has been warming for half an hour is a much easier start.
If your bedroom is genuinely cold, below about 12°C, or you are over 65 or have a heart or lung condition, NHS winter guidance is to keep the rooms you use warm, and the advice here about a cool room should give way to that. Cold homes are a health risk in their own right.
Stop the draughts
A cold bedroom is often a draughty one. Draught strip around the window and along the bottom of the door, a heavy lined curtain that reaches the sill (and tucks behind the radiator rather than over it), and moving the bed away from an outside wall or a single-glazed window all help. Thermal blackout curtains do double duty, keeping light out and heat in; there is more in the guide to making your bedroom darker.
If you are waking hot
This is the most common winter complaint, and it usually means the room or the duvet is too warm for you. Turn the heating off earlier, drop a tog, or swap the fleece pyjamas for cotton, and try one change at a time. If you are waking sweaty regardless of the season, the guide to waking up hot at night looks at the other reasons worth ruling out.
The short version
Socks on, hot water bottle in the bed twenty minutes early, heating off before you go up, duvet matched to the season with a throw on top to push off if you need to. The best temperature for sleep guide explains the reasoning behind the cool-room advice, and the other Sleep Environment guides cover light, noise and bedding.
Sources and further reading
- NHS: Keep warm, keep well
- NHS: Sleep and tiredness
- Frontiers in Neuroscience: Harding EC, Franks NP, Wisden W. The Temperature Dependence of Sleep. Frontiers in Neuroscience, 2019
- Electrical Safety First: Electrical Safety First
Written and reviewed by the Quiet Mind Sleep editorial team in line with our editorial policy. Spotted an error? Let us know.
