Too hot to sleep? 7 things that can make you overheat at night

Tom's Guide

15-06-2025

We can all get a bit hot and sweaty during warm summer nights, but sometimes there's more going on in the body causing us to overheat in bed.
There is a close connection between body temperature and ability to fall asleep, as your circadian rhythm relies on temperature cues among other things. Our bodies snooze best in cool temperature, which means that sleeping on one of this year's best cooling mattresses can boost your quality of sleep.
However, there are several environmental, lifestyle and health factors that disrupt our body's ability to regulate temperature.
We've spoken to Dr. Emma Lin, a board-certified Pulmonologist and Sleep Medicine Specialist and Co-Founder of ReadyO2, and Ana Schick, BA, CPT, CHC, Resident Sleep Expert and Health Coach at Sleepme to find out exactly what may be causing us to run hot at night, and what we can do to sleep better in the heat.
There are many different reasons why you could (always or occasionally) be sleeping hot, from lifestyle choices to medical conditions and hormonal changes…
Schick says hormonal shifts, specifically a drop in estrogen during perimenopause and menopause, can "override your body's built-in thermostat, leading to sudden heat surges known as hot flushes."
These can happen at any time of day, but are commonly more intense and frequent at night.
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'Estrogen has a big role in regulating our cardiovascular system,' which is "heavily involved in what we call thermo regulation – the center of the body that controls our heat," Dr. Sarah Jenkins, who we spoke to for our feature on sleep problems during menopause, explains.
"And when we have an estrogen deficiency, we can get hot flushes. Hence, you can wake up really hot in the night, literally soaking the bed sheets with sweat," she adds.
Even before perimenopause arrives, women won't be strangers to a sweaty, sleepless night. Changes in hormone levels throughout their menstrual cycle can trigger hot flushes, says Lin.
Estrogen levels also drop just before a woman comes on her period. This impacts the hypothalamus, which is responsible for regulating body temperature.
The brain becomes more sensitive to temperature changes, leading to increased sweating or feelings of heat during the night.
Lin adds that men experience this temperature fluctuation too, if they have low testosterone levels.
From sunlight exposure to your exercise routine, what you do during the day has a surprising impact on how well you sleep at night, and your diet is one of the key players here too.
In terms of temperature regulation, there are certain foods that raise your body temperature in the metabolism process.
Schick says that caffeine (a well-known sleep disruptor) can increase body heat, alongside spicy foods containing capsaicin, which temporarily raises body temperature as it stimulates heat receptors.
Also note that the time you eat can impact your sleep. Eating large meals late at night will mean your body is still metabolizing food when you go to bed.
Think of your body as a well-fueled machine — its temperature will be raised while working to break down this food, rather than winding down (and cooling down) to sleep.
"High-stress levels can trigger cortisol-driven temperature dysregulation," says Schick.
When we're stressed, our bodies release more hormones like cortisol and adrenaline, which increase heart rate and blood flow. Ultimately, this leads to an increase in body temperature, fighting against the body's urge to sleep.
Hence, it is useful to follow deep breathing exercises at night to help your body calm and cool down before hitting the hay. Having tried them ourselves we recommend moon breathing and the 4 7 8 sleep method.
Your bedroom may be lovely and cozy, but is it at the optimal temperature for sleep? You may need to adapt your sleep set-up to accommodate the warmer weather during summer months.
It's important to make sure your bedding and sleepwear is breathable, to allow good airflow during the night and to help wick away moisture, preventing you from getting clammy and uncomfortable.
You may even need to change up your mattress to help with temperature regulation. As mattresses age, their materials wear down, becoming less breathable and more likely to trap heat.
We recommend a top-rated cooling mattress with specialist climate control tech to anyone struggling to beat the heat at night.
Schick explains that alcohol can dilate blood vessels, increasing blood flow to the skin and leading to a flushed feeling.
A study published in the America Journal of Physiology, which assessed the impact alcohol consumption had on the circadian core temperature of nine healthy men, concludes alcohol consumption increases nocturnal core body temperature by an average of 0.36°C (0.65°F).
Hence, you may overheat in bed after a night on the booze. A 2020 study by French researchers also shows alcohol disrupts the natural circadian rhythm and melatonin production alongside thermoregulation mechanisms.
Leaving you feeling hot and dysregulated, alcohol consumption often results in poor sleep quality.
Alcohol and smoking are often put on par when it comes to compromising health. Similarly to drink, smoking, specifically nicotine, can dysregulate body temperature.
A 2021 study of over 600 Lebanese women, 62.5% of which experienced hot flushes, noted a "statistically significant difference [...] between women who experience hot flashes and their counterparts with respect to smoking."
Smoking cigarettes can lower estrogen levels, narrow blood vessels and increase heart rate and blood pressure. All of which can alter temperature regulation in the body.
Thermoregulation within the body plays a vital role in how well we sleep. Of course, tossing and turning in a sweaty fluster is not conducive to peaceful sleep, but there's more going on inside the body which stops you sleeping when you're hot.
Temperature is a key circadian rhythm cue. This means it helps regulate the body's internal biological clock, influencing sleep-wake cycles and hormone release.
For sleep-inducing hormones, e.g. melatonin, to be released, your core body temperature needs to drop. Therefore, reducing your temperature in the evening and maintaining a cool sleep space is crucial to getting restorative rest.
"Managing hot sleep starts with optimizing your sleep environment, routine, and thermoregulation," says Schick. How do you do this? Here's what she recommends...