Sleeping Hot? Here Are The Causes — And The Solution

There are a lot of things that go into a good night’s sleep. Too much light, too much noise, or a sleeping environment that’s just too darn hot can make for a lot of tossing and turning. But even if your bedroom is in the perfect temperature range, your choice of bedding, pajamas, pre-bed activities, and other factors can all mean you wake up in the night feeling hot and sweaty. We spoke to a few sleep experts to learn more about all the reasons you might be sleeping hot, plus what you can do to stay cooler and more comfortable at night.

Fast Facts on Sleeping Hot

As core body temperature dips at night to promote sleep, skin temperature may rise, making us feel hot.
External factors can also make us feel hot at night, including bedding and pajamas, pre-bed activities, hydration level, hormones, and illness.
In many cases, simple changes like adjusting room temperature, drinking plenty of water, and restricting caffeine and alcohol consumption can help you sleep cooler.

Why Do We Get So Hot When We Sleep?

You can blame biology to some degree if you tend to overheat at night. Dr. Carlea Weiss, PhD, MS, RN, and sleep scientist, tells Sleepopolis that our core body temperature naturally dips slightly to promote sleep onset. “When that occurs, the skin temperature may rise to help release heat,” she says. “That is often why people feel they get hot during sleep.”

But the external temperature also plays a role because it can affect the body’s ability to self-regulate. That means extra-warm bedding or pajamas, whether you exercise or have sex right before bed, even hormone cycles and illness can all get in the way of a good night’s sleep.

Room Temperature and Humidity

“The best temperature varies from person to person, but optimal sleep generally occurs in cooler temperatures,” Audrey Wells, MD and founder of Super Sleep MD tells Sleepopolis. “Personal preference, age, health conditions, and climate (including humidity) can influence what feels comfortable.” Generally, a temperature somewhere between 60 and 67 degrees Fahrenheit is the most conducive for sleep. When the thermostat begins creeping above that range, it can affect the body’s ability to regulate itself properly. That’s why many people experience abnormal sleeping patterns in the summer, according to survey answers from 765,000 participants in a 2017 study. (1)

But it’s not just the room temperature that presents a potential problem. It’s the humidity level. A high amount of water vapor in the air can make it harder for the body to cool itself down, since sweat on the skin is unable to evaporate properly. (2)

Before-Bed Activities

What you do before bed can likewise affect your body temperature:

High-impact exercise. While there is evidence of a strong relationship between exercise and healthy sleep, timing is important (3). Vigorous exercise — the kind that makes you sweat — close to bedtime may not give the body enough time to cool its core temperature. According to Weiss, some people may think that high-impact exercise promotes sleep because it triggers sweating, which can cool skin temperature. But for sleep, it’s the core body temperature that matters. “Relaxing activities such as yoga and stretching are better options before bed,” says Weiss.
Sex. While sex can promote relaxation, making it easier to fall asleep, particularly vigorous sexual activities that raise your heart rate for an extended period of time can have the same negative effect as intense exercise.
Lack of hydration. It’s not unusual to wake up feeling dehydrated, since the body naturally loses water through breathing and sweating. At night, we aren’t sipping water to combat this loss. But going to bed dehydrated also affects body temperature. “Dehydration reduces the ability to tolerate heat, as the body produces less sweat and may also have a reduced skin blood flow,” says Weiss.
Caffeine. That caffeinated afternoon pick-me-up may have lasting effects come bedtime. “As a stimulant drug, caffeine increases core body temperature (4),”says Weiss. Since the half-life of caffeine is roughly five hours, it stays in your system long after you consume it (5). Depending on how well you metabolize caffeine, which relates to factors like age, body weight, gender, genetics, health conditions, and more, its temperature-boosting effects could affect your body’s ability to cool itself in preparation for sleep.
Alcohol. Weiss tells Sleepopolis that alcohol has a rebound effect. “Even though it can make people sleep, once it’s metabolized, it increases cortisol levels, negatively impacting sleep,” she says. Additionally, alcohol may make you feel warmer — though it technically lowers your core body temperature, alcohol also causes blood to rush to the skin’s surface, which causes that expected feeling of warmth. (6)
Stress. Stress is associated with a rise in cortisol levels, which may increase core body temperature and harm sleep, says Weiss.

Warm Bedding and Sleepwear

You may love the feeling of soft flannel pajamas or being cuddled up with piles of blankets, but proceed with caution! Heavy pajamas and fabrics that trap heat can both increase skin and core body temperature. Weiss says that can lead to fragmented sleep, meaning you wake back up repeatedly in the night because you’re too hot, and struggle with the inability to fall back asleep.

Memory foam is also infamous for retaining body heat. It’s a popular mattress material, but unless you’re opting for gel-infused or ventilated versions, it could make for hot nights.

A Warm Sleeping Partner

Sharing your bed with a romantic partner may be associated with better sleep quality and even improved mental health (7), but couples may notice it could also mean there’s an extra source of heat in bed with you — the same is true if you’re sleeping with a pet. In both cases, that means an elevated temperature both under the covers and in the room itself.

Hormones

For women, hormonal fluctuations relating to ovulatory cycles, pregnancy and menopause, can mean hot nights. “A rise in progesterone during the luteal phase of the menstrual cycle is linked to an increase in core body temperature and sleep disturbances,” says Weiss. This phase of a woman’s menstrual cycle happens right after ovulation and lasts roughly 14 days. The progesterone increase during this time can lead to symptoms like night sweats, which are also common during menopause. Hot flashes, another well-known menopausal symptom, “also increase body temperature and cause sleep disturbances,” says Weiss.

During pregnancy, hormonal changes are more exaggerated, which means a slightly increased body temperature with each trimester. That’s also because the body is working harder than usual, with a higher heart rate and faster metabolism. (8) It’s normal and expected, but it can make it harder to feel cool and comfortable at night.

Medication

There are a lot of medications that can influence body temperature, either by raising it or affecting thermoregulation. Dr. Weiss listed the following:

Stimulants
Beta blockers
Anti-seizure medications

Certain kinds of steroids, painkillers like aspirin or acetaminophen, hormone therapy medications, and diabetes medications can also affect body temperature, which may lead to sleep disturbances. (9)

Illness or Infection

“Illness or infection can cause an increase in core body temperature and affect sleep,” says Weiss. “However, due to other physiological mechanisms, we often observe individuals experiencing fatigue and prostration while sick.” These illnesses include flu, strep throat, pneumonia, or bacterial infections. Other health conditions that can affect how hot you feel at night include hyperthyroidism, chronic stress, hyperhidrosis, coronary heart disease, and cancer. (10) (11)

Solutions for Sleeping Hot

If you’re sleeping hot, step one is figuring out what might be causing it. As soon as you can pinpoint the trigger, you can take steps to remedy the situation for cooler nights.

Cool down a warm room. Try lowering the thermostat, using an oscillating fan, opening a window, or taking a cool shower before hopping into bed.
Upgrade your bedding. Switch out warmer bedding for breathable sheets. Take a good long look at your pajamas too, and switch to lighter options — or try sleeping naked. This can be helpful if you suspect fluctuating hormones are making you sleep hot.
Be mindful about pre-bed activities. Shift that intense workout to earlier in the day, and try curbing your alcohol and caffeine intake.
Hydrate properly during the day. Guzzling a bunch of water before bed may mean waking up in the night to race to the bathroom, so make sure that you’re drinking throughout the day.
Consider a sleep divorce. If your problem is that extra heat source in bed with you, you may want to try sleeping in separate beds.
Speak to your doctor. If you suspect medications are causing you to sleep hot, speak to your doctor about alternatives.

FAQs

What causes night sweats?

“Several medical conditions can cause night sweats, such as menopause, sleep disorders, obstructive sleep apnea, and cancer like Hodgkin’s lymphoma,” says Weiss. She says the same is true of certain medications, including antidepressants, hormones, and opioids. If nighttime sweating is affecting your sleep quality, speak to your doctor.

Why do I radiate heat at night?

In preparation for sleep, core body temperature dips slightly. As a result, skin temperature can rise to help release body heat. External factors like room temperature, bedding, pajamas, and anything you do right before bed can also make you feel noticeably warm.

What happens to your body temperature when you sleep?

It’s normal for body temperature to dip during sleep. “A drop in core body temperature is a signal for sleep, and this naturally occurs as part of the circadian rhythm in the evening,” says Wells. “Body temperature naturally reaches a low point at about two hours before a person’s usual wake-up time.” The body is cued into wakefulness by a rising core body temperature.

The Last Word From Sleepopolis

In many cases, people can address overheating at night on their own. “Healthy individuals can make simple adjustments without help conditions, such as adjusting room temperature, drinking plenty of water, and restricting caffeine and alcohol consumption,” says Weiss. If those changes aren’t having a positive impact, double check with your doctor that there isn’t an underlying medical condition that’s making you sleep hot.

Dr. Carlea Weiss. Personal interview. August 2024.

Dr. Audrey Wells. Personal interview. June 2024.

Obradovich, N et al. Nighttime temperature and human sleep loss in a changing climate. Science Advances.2017. doi: 10.1126/sciadv.1601555
Okamoto-Mizuno K, Mizuno K. Effects of thermal environment on sleep and circadian rhythm. J Physiol Anthropol. 2012 May 31;31(1):14. doi: 10.1186/1880-6805-31-14. PMID: 22738673; PMCID: PMC3427038.
Dolezal BA, Neufeld EV, Boland DM, Martin JL, Cooper CB. Interrelationship between Sleep and Exercise: A Systematic Review. Adv Prev Med. 2017;2017:1364387. doi: 10.1155/2017/1364387. Epub 2017 Mar 26. Erratum in: Adv Prev Med. 2017;2017:5979510. PMID: 28458924; PMCID: PMC5385214.
1. McHill AW, Smith BJ, Wright KP. Effects of caffeine on skin and core temperatures, alertness, and recovery sleep during circadian misalignment. J Biol Rhythms. 2014;29(2):131-143. doi:10.1177/0748730414523078
Institute of Medicine (US) Committee on Military Nutrition Research. Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations. Washington (DC): National Academies Press (US); 2001. 2, Pharmacology of Caffeine. Available from: https://www.ncbi.nlm.nih.gov/books/NBK223808/#
.Should You Worry About Facial Flushing? Cleveland Clinic. Published October 26, 2018. https://health.clevelandclinic.org/facial-flushing-should-you-worry-if-your-face-turns-red-when-you-drink/
Brandon Fuentes and others, 0010 Bed Sharing Versus Sleeping Alone Associated with Sleep Health and Mental Health, Sleep, Volume 45, Issue Supplement_1, June 2022, Page A4, https://doi.org/10.1093/sleep/zsac079.009
Soma-Pillay P, Nelson-Piercy C, Tolppanen H, Mebazaa A. Physiological changes in pregnancy. Cardiovasc J Afr. 2016 Mar-Apr;27(2):89-94. doi: 10.5830/CVJA-2016-021. PMID: 27213856; PMCID: PMC4928162.
What Causes Night Sweats? WebMD. (2022). https://www.webmd.com/a-to-z-guides/ss/slideshow-night-sweats
Hot Flashes and Night Sweats (PDG) – Patient Version. National Cancer Institute. https://www.cancer.gov/about-cancer/treatment/side-effects/hot-flashes-pdq
Night Sweats. Cleveland Clinic. (2022). https://my.clevelandclinic.org/health/symptoms/16562-night-sweats