Your body needs to cool down to fall asleep

Falling asleep isn't something you do so much as something your body allows to happen, and one of the signals it needs is a drop in core temperature. In the evening your internal thermostat nudges your core temperature down by roughly half a degree, and that gentle cooling helps trigger the release of melatonin. If your bedroom is stuffy, that process is working against you — you tend to lie there restless, throw the duvet off, drift off eventually, and then wake in the small hours.

The commonly quoted ideal bedroom temperature is around 16–18°C. That can sound chilly for a British home in November, but it's a room temperature, not a bed temperature. Under a decent duvet, 17°C feels comfortable and inviting rather than cold, and most people sleep noticeably better for it.

Light is the other half of the equation

Light is the strongest cue your body clock has. Bright light in the evening — from a ceiling light, a laptop, or a phone held close to your face — tells your brain it's still daytime and that melatonin can wait. The result is a later, lighter sleep and a foggy start the next morning.

Even small amounts matter. A standby light glowing across the room, a streetlamp leaking round the edge of a curtain, or a hallway light creeping under the door can all be enough to disturb the deeper stages of sleep. Darkness isn't a luxury; it's part of the setup.

Get the temperature right before you get into bed

Deal with this an hour or two before bed, rather than once you're already under the covers.

• Turn the heating down or off in the bedroom. If you have thermostatic radiator valves, set the bedroom one lower than the rest of the house.
• Open a window for ten minutes to flush out warm, stale air, then close it again before you get in. A wide-open window all night suits some people, but if you're woken by traffic or cold feet, a short airing is the better compromise.
• Choose a lighter tog duvet for summer and consider a 4.5 tog or a cotton blanket during warm spells.
• Natural fibres — cotton, linen, wool — breathe far better than polyester, so you sweat less and wake less.
• Keep a glass of water by the bed; a warm room and mild dehydration go together.
• If your bedroom sits above a boiler or an airing cupboard, close the door on that heat rather than letting it drift upstairs.

A note for older houses: sash windows, single glazing and gaps under doors let a room cool quickly, which is helpful in summer and less so in January. Thick curtains and a draught excluder hold the temperature steadier rather than letting it swing.

Make it properly dark, not just dim

• Fit a blackout lining or a blackout blind — particularly useful in a city, or in summer when the sun rises before five.
• Hang curtains so they overlap the window frame and meet in the middle. Light leaking at the edges is what wakes most people.
• Deal with standby lights. A small piece of electrical tape over an LED takes seconds and makes a real difference.
• If you get up in the night, use a low, warm-toned night light rather than flicking on the main light.
• An eye mask is a perfectly respectable solution, especially for shift workers or anyone sharing a room with a different schedule.

Keep screens away from the pillow

The single most useful change most people can make is to stop looking at a bright screen in bed. It isn't only the light; it's that scrolling keeps your mind ticking over, and the last thing you want is to arrive at sleep already wound up.

Try to finish with screens at least an hour before bed, and keep chargers and phones out of arm's reach — ideally charging in another room. If you use your phone as an alarm, switch it to aeroplane mode and leave it across the room so you have to get up to silence it. That small inconvenience is a surprisingly effective alarm clock.

A simple wind-down routine for cosy evenings

Cosiness and good sleep aren't in conflict. The trick is to make the last hour of the evening deliberately quiet: warm in atmosphere, cool in temperature, and low in light.

• Dim the lights an hour before bed — use a lamp with a warm bulb rather than the main ceiling light.
• Have a warm drink, such as a milky drink or herbal tea. Keep it modest in size so you're not up in the night.
• Warm your feet, not your room. A hot water bottle at the foot of the bed or a pair of bedsocks helps you fall asleep faster while the room stays cool.
• Do something slow with your hands: reading a paper book, folding laundry, a few gentle stretches.
• Keep a regular bedtime, roughly the same each night, including at weekends where you can manage it. Your body clock likes routine even more than it likes the perfect bedroom.

None of this needs to be expensive or complicated. Cool the room, darken it properly, put the phone down, and give yourself twenty quiet minutes. Most people notice the difference within a week — and the evenings feel more restful long before your head hits the pillow.