To fall asleep, and to stay asleep, your core body temperature needs to fall. It is part of the body's natural wind-down at night. Your skin warms slightly as heat leaves through your hands and feet, and your core cools.
A warm bedroom works against that. When the room, the bedding or the body stays warm, the system has to work harder to shed heat, and sleep tends to become lighter and more broken. People often describe it as waking in the early hours, a little warm, and finding it hard to drift back off.
This is also why a warm night and a hard session can stack. Heavy training raises your recovery demands at exactly the point when you most need deep, uninterrupted sleep.
You do not need anything expensive to start. These are the changes I come back to first.
Most people sleep best in a bedroom that is cool, commonly cited at around 16 to 19°C. In summer, close curtains in the afternoon, open windows once the evening cools, and use a fan for airflow.
Natural fibres such as cotton, linen or wool breathe better than synthetics and hold less heat. Swap the winter duvet early.
Try it an hour or two before bed. It sounds counterintuitive, but warming the skin helps the body release heat afterwards, which supports the drop in core temperature.
Both can raise your overnight heart rate and lower HRV, and a large dinner keeps the body working when it should be winding down. Finishing dinner earlier makes a noticeable difference for many people.
A very intense session late in the evening can leave you warm and switched on. If evening is your only option, allow a proper cool-down and a longer wind-down afterwards.
Wearable data on HRV and resting heart rate can show you a trend. It is useful for noticing patterns, not for judging yourself each morning.
Temperature was the one thing I had never properly controlled. I had been keen to try the Eight Sleep Pod 6 for some time, so when Eight Sleep got in touch about a paid partnership, I was genuinely pleased to test it.
I have now been using it for two weeks. A thin cover sits over your mattress and adjusts the temperature on each side of the bed through the night, so two people can each set their own. In that time, my sleep has improved far more than I expected. My sleep score has gone from the 50s and 60s to the high 80s. I see it on both my Garmin and the Eight Sleep app.
Two weeks is early, and I will share the data and a fuller review once I have had longer with it. But I wanted to tell you now, because I would never recommend something to my patients, or to you, that I have not tried myself and believe in.
A short video on the Pod 6, and my first impressions after two weeks.
Watch the video on Instagram →A temperature-adjusting mattress cover with independent settings for each side of the bed.
If you are doing everything right and still waking unrefreshed, or you snore heavily, stop breathing in your sleep, or feel exhausted through the day, please speak to your GP. Persistent sleep problems are worth investigating properly, and temperature is only one piece.
Training only pays off if you recover from it. I hope some of this helps you protect the night.
This newsletter is general information only and is not a substitute for individual medical advice.
