Too hot to sleep

Do you tend to get hot at night? Then you are one of 40% of people that tend to overheat at night. In particular during the hotter months sleeping cool can be difficult, but also other factors can make us overheat at night. Read more about it and what you can do to enjoy a cool night's comfort.

Why do I get so hot when I sleep? | How does being hot at night impact my sleep? | How can I enjoy a cool night's sleep?

The causes

Why do I get so hot when I sleep?

There are a number of factors that can cause us to overheat at night. Some of them might be medical in which case you should contact your doctor. By understanding why we are hot at night we can begin to find the solutions for cooling down.


If you have eaten a heavy meal, red meat or other types of foods that are difficult to digest just before going to bed you keep your metabolism awake at night. This can cause us to overheat. Some drinks that contain caffeine can also elevate our body temperature at night and too much alcohol can lead to night sweats and overheating. As Dr med Lutz Graumann puts it: "A no-go for good sleep is alcohol. The moment we drink alcohol, there is absolutely no restorative sleep. You can even see that your resting heart rate is elevated by up to 10 beats the whole night just because it."


Being physically active is closely linked to a good night’s sleep however, if we are exercising too close to bedtime our body temperature can be elevated making it difficult to fall asleep and to enjoy the best temperature for sleep.


When we are feverish our body temperature rises and we can start to sweat at night. If our bedding or pjs become wet this can lead to cold sweats as we become uncomfortably cold and start to shiver. There are a number of illnesses like chronic stress, cancer and heart disease that can lead to overheating at night. If you think you have a medical problem please contact your doctor.


Hormonal changes can impact in particular women’s sleep, from menstruation to pregnancy and menopause. These changes can lead to hot flashes and overheating at night.


If the ambient temperature is too high we easily overheat at night. Our bedrooms are actually on average 5ºC/ 41 °F warmer today than they were 5 years ago. During the REM sleep phases, the dream phases, our natural thermo-regulation ability is impaired making it even more important to have the right room temperature when we sleep. Dr Rebecca Robins, (PhD, researcher Harvard Medical School) explains: ”A warm room being good for sleep is actually a myth, although believed by many. A cool temperature is absolutely essential for sleep, as a low core body temperature is associated with shorter sleep onset, but also, a warmer environment causes more sleep fragmentation and nightmares.”


Bedding and sleepwear that aren't breathable can trap in heat making it easier to become too hot to sleep. As a result you start to sweat and if you have the wrong fabrics next to your skin you can become wet and cold. This is important all year, but having the best summer pajamas is particularly key as the ambient temperature is higher.

The impact

How does being hot at night impact my sleep?

Temperature has a huge impact on our sleep quality and duration. As Dr med Lutz Graumann puts it: "Thermoregulation is key for a good night's sleep. To fall asleep and to enjoy a deep, restorative sleep we need for our core body temperature to drop, but if we get too cold we will shiver and our sleep quality suffers."

If we get too hot at night we will start to sweat while sleeping and if our sleepwear gets wet we often become cold afters starting to shiver. To stay in the restorative, slow-wave sleep phases temperature regulation plays a big role. It's in these sleep phases that we get the most rest.

The action

How can I enjoy a cool night's sleep?

There are a number of changes we can make in our daily routine to help us enjoy a cool night's comfort even as the temperature rises.

Getting a cool night’s comfort starts already during the day. There are some cooling tips to make sure your body and your bedroom don’t overheat.

1. Cool down your bedroom: make sure that you have windows and blinds shut during the day to prevent your bedroom from warming up. This can make a real difference to your room temperature and to your air conditioning bill (if you have one).

2. Exercise at the right time: when we exercise our body temperature elevates. In hot weather it’s better to exercise earlier in the day so that our body temperature has time to drop before going to bed.

3. Eat a cooling diet: food that is difficult to digest like fried food and red meat keep our digestive system working during the night which will increase our body heat. By eating a light meal at the end of day we can keep cool at night.

4. Keep hydrated: make sure that you keep hydrated during the day, but avoid caffeinated drinks or alcohol just before going to bed.

To fall asleep our core temperature needs to drop, we can help this process:

1. Cool down your bedroom: when the sun is down and temperature hopefully has decreased you can welcome that cool air back in. You can try hanging a damp or wet sheet in the window for further evaporative cooling. Our bedrooms should ideally be below 18°c / 64.5°F.

2. Cooling sleepwear: put on cooling pajamas to make sure you don’t overheat again. Go for lightweight and breathable materials to avoid heat build-up. Natural materials tend to be more breathable than synthetics.

3. Cooling bed sheets: use natural materials that are light like from botanic fibres such as microlyocell (Tencel) or linen.

1. Cooling air flow: use a bed fan to keep the air flowing through the room. For additional cooling you can keep a bucket of ice just in front of the fan to further cool down the air. You can also install air conditioning if the temperature remains high.

2. The right mattress: memory foam mattresses can trap heat. There are other options out there that lead heat away from the body and help you to avoid overheating and sweating while sleeping.

3. Space out in bed: keep some space between you and your partner and make sure that dogs and kids sleep in their own beds. Body heat from others will heat us up further during the night.

4. The best cooling pajamas: by sleeping in light-weight breathable sleepwear we can make sure that we stay cool all night long. Cooling sleepwear should have a dual moisture management approach: cooling you down through evaporative cooling and keeping you dry through moisture wicking.

The sleepwear solution

The best cooling pajamas

Dagsmejan's Stay Cool sleepwear is designed to keep you sleeping soundly even when the temperature rises. The cooling nightwear is 8x more breathable than cotton and dries in 1/3 of the time. Made with botanic fibres from eucalyptus combined with the latest textile technologies this ultra-light sleepwear keeps you cool even in the hottest months.