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.

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

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.

Jessica Timmons

Jessica Timmons has been working as a freelance writer since 2007, covering everything from pregnancy and parenting to cannabis, fitness, home decor, and much more. Her work has appeared in Healthline, mindbodygreen, Everyday Health, Pregnancy & Newborn, and other outlets. She loves weight lifting, a good cup of tea, and family time. You can connect with her on her website, Instagram, and LinkedIn.