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Why You Get Hot When You Sleep, According to Experts

The hot sleepers of the world bear a brutal curse, but, mercifully, it doesn’t have to be permanent.
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Fast Facts

  • Body temperature is regulated by your internal clock, also known as a circadian rhythm, and naturally cools as the sun sets.
  • Sometimes, this process can be hindered by environmental factors that can be easily addressed, whereas others may signal more significant health issues.
  • Investing in cooling bedsheets, prioritizing proper room ventilation, and addressing underlying medical concerns may help.

Something doesn’t add up here. Your thermostat reads 65, but your sweat-soaked pajamas and mountain of displaced blankets tell a different story; one that ends in you waking up every morning feeling like you haven’t slept a wink. Why do you struggle with overheating while your bed partner so easily drifts off to dreamland? There are many potential reasons you run hotter at night and, thankfully, most of them have solutions.

What Happens to Your Body Temperature as You Sleep

Body temperature is regulated by your internal clock, also known as circadian rhythm, explains Abhinav Singh, M.D., M.P.H., F.A.A.S.M., medical director of the Indiana Sleep Center, medical review panelist for Sleep Foundation and co-author of Sleep to Heal. As the sun sets and outdoor temperatures fall, the body naturally cools down. It happens to all mammals who are awake during the day and sleep at night.

“That’s been set up by design for the body to transition from wake mode to sleep mode,” Dr. Singh says of the inherent drop. “Lack of light, as well as the cooling temperatures, synchronize with the body’s ability to fall and stay asleep.”

He adds that this process directly supports the release of the sleep hormone melatonin (1), and if the cycle is disrupted for whatever reason, the body will often perspire to cool down. “People sweat essentially to lower body temperature,” he explains.

Why You Get Hot at Night

A number of factors could be at the root of your sleep sweats. Some of them are environmental and can be easily addressed, whereas others may signal more significant health issues. According to medical experts, these are the most common causes.

Your Room Is Poorly Ventilated

Perhaps your bed partner runs a little colder than you do, so the fan gets pointed away from the bed or worse, isn’t turned on at all. Proper air ventilation at night is crucial, Dr. Singh says, and should be achieved with a fan, air conditioning, or both. And contrary to popular belief, there is no magic temperature for sleeping. “It should feel cool,” Dr. Singh states simply. “Meaning, whatever temperature you’re used to, it should feel cooler than that.”

Your Sleep Setup Is Stuffy

As obvious as it may sound, if you’re sleeping in flannel sheets or pajamas, they could very easily be the culprit. Your mattress could be, too, especially if it’s old, stuffy, and holds too much heat in, Dr. Singh says.

You’re Stressed

If you ever wake up to a racing mind and, yes, a sweaty body, the two symptoms could be linked. Stress causes your “motor,” as Dr. Singh puts it, to keep running, which means it doesn’t have time to cool down, and neither do you.

You’re Training Too Hard

If you’re a marathon runner or someone who lifts often, Dr. Dahl says you may get warmer than usual during sleep. “Recovery that happens at night can produce a lot of heat,” he explains.

You Don’t Change Sleep Positions Enough

Though it may be surprising, Dr. Singh says it’s perfectly normal, and actually encouraged, to roll around a bit at night. Not only does it prevent soreness from sleeping too long in one position, but it also helps keep air flowing around your body and prevents any particular spots from collecting sweat. Dr. Singh says healthy adults typically experience 20 to 30 position changes per night.

You Have an Underlying Medical Condition

A myriad of medical conditions can cause body temperature to fluctuate at night. A few of the most common, according to Dr. Singh and Nick Dahl, D.O., a physician whothat works with Hone, are:

  • Thyroid imbalance: If your thyroid is overactive (also known as hyperthyroidism) or you’re taking too much thyroid medication, the imbalance can cause you to overheat.
  • Low testosterone: Around 38 percent% of men 45 years or older (2) experience low testosterone, which contributes to overall poor sleep and can manifest through night sweats, per Dr. Dahl.
  • Menopause: Hot flashes and night sweats are tell-tale symptoms of hormonal changes that happen to women as they age.
  • Sleep apnea: Breathing interruptions caused by sleep apnea are like “micro-panic attacks,” explains Dr. Singh, which not only jolt you awake, but also spike heart rate and adrenaline levels, causing the body temperature to rise briefly.
  • Obesity: “People who are obese have a layer of fat that is an insulator, which may cause them to sweat,” explains Dr. Dahl. Singh concurs, adding that the extra surface area and skin folds can collect perspiration.
  • Infection: Various infections can cause night sweats, according to Dr. Dahl, from cancer to tuberculosis.
  • Prescription side effects: Certain prescriptions for chronic conditions, such as some antidepressants and heart medications, can also cause unwelcome sleep sweats, according to Dr. Singh.
  • Body temperature is regulated by your internal clock
  • Lack of light, as well as the cooling temperatures, synchronize with the body’s ability to fall and stay asleep
  • If the sleep cycle is disrupted for whatever reason, the body will often perspire to cool down

How You Can Stop Overheating at Night

Follow these tips for a cooler night’s sleep, and learn when it’s time to see a doctor.

Cooling Materials Are Key

Lightweight sheets, blankets, and clothing—ideally made of cotton or other natural, woven materials like bamboo—can help you stay cool at night. “Cotton is king when it comes to breathability,” explains Dr. Singh. “Anything synthetic is just not good enough.” If those don’t make enough difference, try opting for a cooling mattress or mattress pad.

Prioritize Proper Ventilation

“Have a small fan running to circulate air around the room,” recommends Singh. “Even if you have air conditioning or a ceiling fan.”

Take a Hot Shower

It’s Dr. Singh’s “secret hack” for better sleep. “It sort of warms up the skin and allows the blood vessels to dilate on the surface of the skin, allowing more surface area for heat loss,” he explains.

Address the Underlying Problem

If you try all of the known tips and tricks and still struggle to get comfortable, Dr. Singh recommends sharing your experience with a doctor and discussing treatment options best suited for you.

The Bottom Line

Waking up in a puddle of sweat isn’t just annoying—it could also be affecting your quality of sleep and overall health. Try manipulating environmental factors to regulate your body temperature, and if nothing seems to work, speak to your doctor about a potential underlying medical condition.
References:
1. Masters, Alina et al. “Melatonin, the Hormone of Darkness: From Sleep Promotion to Ebola Treatment.” Brain disorders & therapy vol. 4,1 (2014): 1000151. doi:10.4172/2168-975X.1000151

2. Mulligan, T et al. “Prevalence of hypogonadism in males aged at least 45 years: the HIM study.” International journal of clinical practice vol. 60,7 (2006): 762-9. doi:10.1111/j.1742-1241.2006.00992.x

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