Wondering why your body gets so hot when you sleep, and your bed is slowly becoming a cesspool of sweat? You’re not alone. There are many hot sleepers like you. In a medical study researching night sweats with 2267 participants, as much as 41% experienced night sweats. 

In other words, your condition is pretty prevalent. But why does it happen? Is it more common in young or older people? Is it more prevalent in women than men? What can you do about it? Is it treatable, or is it long-term?

To answer these questions, read below as we aim to bring light to this issue that has ruined and continues to ruin many people’s sleep in the UK and worldwide. 

Reason 1: Room Temperature and Humidity

Biologically speaking, room temperature and humidity influence core temperature and play a vital role in keeping a good night’s sleep.

Ask everyone you know if they can sleep with temperatures soaring on both spectrums (too warm and too cold), and almost anyone would say they can’t. 

According to a physiological study, our circadian rhythms (body clock) can be easily influenced by environmental conditions such as temperature. The study concludes that heat significantly increases wakefulness and decreases sleep quality. 

Combine a warm temperature with humidity, and you’ll have many more problems. If you sweat profusely because the temp and humidity are high, your sweat will take a lot more time to evaporate—leaving you with a literal feeling of taking a bath out of your sweat instead of staying cool.

Try to keep the thermostat low to have a conducive temperature for sleep and prevent overheating.

Reason 2: You Have Hyperhidrosis—an Excessive Sweating Disorder

Another possible culprit of getting hot during sleep is a common medical disorder: hyperhidrosis. This is characterised by excessive sweating in the palm of your hands, soles of your feet, back of your knees, or armpits. Hyperhidrosis often goes hand-in-hand with high thermostat temps and hot sleepwear. 

Doctors and researchers have studied hyperhidrosis for decades, yet findings are inconclusive, and the exact cause of hyperhidrosis is unknown. This makes hyperhidrosis hard to treat, and patients are commonly prescribed short-lasting topical antiperspirants. 

There are emerging treatment options available, the most promising of which is iontophoresis—a medical device with electrodes that you attach to the affected area and is stimulated with tap water to disrupt sweat-producing glands in the skin. 

Reason 3: Bedding and Sleepwear

You may not notice it, but your bedding and sleepwear might contribute to the warm temperatures you feel during sleep. Thick beddings trap more body heat, giving your body unnecessary warmth, which makes it hard to stay asleep.

Aside from thick bedding, thick sleepwear might be too warm for you, which impedes your body’s ability to regulate heat, causing night sweats. So, in this case, wearing a thinner set of sleepwear will be good for you. 

Aside from fabric thickness, fabric type also plays a role. In a small study, researchers found that cotton sleepwear promoted deeper sleep, while wool sleepwear promoted sleepiness. 

And lastly, your mattress! Some of the best mattresses for hot sleepers now have phase-changing materials which disperse your heat and it’s easy to see why some sweat at night compared to traditional memory foam.

Reason 4: Activities Before Sleep

There are several heart-pumping activities you might need to sideline if you want to sleep cool. These activities increase your core temperature, making it hard to fall asleep and maintain a deep sleep phase: 

• Consuming caffeine. You’ll need to avoid consuming caffeine close to bedtime if you’re a coffee enthusiast. Some people might even need to avoid consuming caffeine after midday as caffeine can last in the body for up to 9 hours.
• Stressful and alertness-inducing activities. Stressful situations raise your body temperature. There’s even a condition called psychogenic fever—induced by emotional stress. Alertness-inducing activities such as gaming can also negatively impact sleep quality and, subsequently, your sleep cycle. 
• Exercising close to bedtime. It’s not inherently wrong to exercise in the evening. A research study says exercising in the evening doesn’t negatively impact you. However, don’t exercise if you’re going to bed within an hour, as sleep onset may be impaired as skin temperature rises from the surge of blood from your blood vessels.  
• Having sex. Getting intimate with your partner in the sheets late at night promotes relaxation and sleepiness. However, if you do vigorous sex, it counts as exercise—raising baseline heart rate and increasing body temperature at night. 

Reason 5: Your Sleeping Partner

Your sleeping partner may contribute to your overall feeling of warmth. You might already know this, but an extra body in your bed means excess heat since the human body emits heat.

Your sense of warmth may also worsen if your partner sleeps hot; think of it as two pieces of charcoals being near and heating each other. Your partner might also be a cuddler, which magnifies the hot and sweaty feeling you feel. 

If your sleeping partner has four legs and fur, you’re not exempted. Mammals (such as dogs and cats) emit body heat too. A dog’s temperature can typically reach 42 degrees celsius, while a cat’s temperature can reach 38.9 degrees. 

Reason 6: Medications

Certain medications can raise your body temperature. There is a myriad of medications that can modify your body heat. The list below is just a few: 

• Antipyretics (anti-fever medicine) such as acetaminophen
• Anticholinergics
• Corticosteroids such as prednisone
• Psychotropics
• Diuretics (known as water pills)
• Diabetes-management medications
• Beta-lactam antibiotics
• Tricyclic antidepressants 
• Hormone therapy medications

By all means, this is not an exclusive list, and there are many medications out there that may raise your core body temperature. If you experience higher-than-normal temperatures when taking these medicines, contact your GP immediately for appropriate medical advice. 

Reason 7: Hormones

Night sweats in women may be attributed to hormonal changes. Imbalances in hormone levels may lead to night sweats and hot flashes. In women aged 50 and up, hot flashes are prevalent due to menopause. 

For women far from the perimenopausal and menopausal period, PMS or premenstrual syndrome commonly causes night sweats due to changes in the levels of estrogen and progesterone in their bodies.

Pregnancy, sleep apnea, hypothyroidism, and hyperthyroidism can also affect hormonal levels, making them possible causes of hot flashes and night sweats. Other underlying hormone-related medical conditions may also be the culprit.

Reason 8: Illness or Infection

The human body is complex yet wonderful. If you’re unaware, fever and that dreadful feeling of weakness are one of your body’s first lines of defence against microbial invaders. When your body fights an illness, it heats up to potentially kill invaders through body heat. This makes you feel hot and, at times, feel too hot, like you’re burning up.

Infectious diseases, viral or bacterial in nature, commonly cause elevated body temperatures. These may include:

• Colds
• Flu
• Pneumonia 
• Strep throat 
• Tonsilitis 
• Urinary tract infections (UTIs)
• Bronchitis
• COVID-19

Certain routine medical procedures, such as vaccinations, may also cause fever as weakened versions of pathogens are introduced to your immune system to try to teach it to mount an appropriate immune response once “real” invaders come. 

Reason 9: Your Sleeping Positions

You may not notice it, but your sleeping position plays a role in experiencing night sweats. Certain positions can insulate body parts that need ventilation (such as the tummy, back, armpits, neck, and knees). 

For example, if you sleep on your stomach, you may feel warmth in your belly for a few hours and feel the warmth climbing up your body. If you sleep on your back, it completely covers it from ventilation—making you get hot at night. 

If you’re a side sleeper, your back and tummy are exposed, but body parts that emit heat are insulated, such as the armpits, groin area, and the back of your knees. Side sleepers commonly feel their armpits sweating so much because of the position. 

How Does Body Temperature Affect Sleep?

Body temperature and sleep are closely connected. They’re inseparable. Your core body temperature and circadian rhythm are predisposed to follow each other’s timing.

For example, your body temperature naturally decreases when it’s time to sleep. While sleeping, your body temps are still low to accommodate deeper sleeping and help you sleep quicker. However, when it’s time to wake up, your body temps naturally increase. 

Apart from humans, other mammals have these thermoregulatory mechanisms tied to sleeping schedules too.

How To Fix Feeling Hot While Sleeping?

Here are possible fixes to different underlying causes:

Underlying Reason	Fix/Treatment
Room Temperature & Humidity	Turn off the heater Open a window Use air conditioning Use an electric fan Use a dehumidifier  Enjoy a cold shower before sleep Place your mattress on the floor
Hyperhidrosis	Use medical-strength antiperspirants Wear loose clothing  Wear sweat-absorbent clothing Try an iontophoresis treatment
Bedding & Sleepwear	Ditch the extra blankets  Opt for a cooler mattress  Use lightweight sleepwear Use breathable fabrics
Activities Before Sleeping	Don’t exercise within an hour before bed Don’t consume caffeine in the late afternoon or evening Practice mindfulness to avoid stress before bedtime Opt for intimate sex rather than vigorous
Sleeping with a Partner	Use a separate blanket  Use a bigger bed  Consider pausing cuddling for a short while  Buy pet beds for your pets
Medications	Chat with your GP or attending specialist if medications can be altered
Hormones	Chat with your GP or attending specialist for the best treatment option
Illness or Infection	Consult your doctor for effective treatment options
Sleeping Position	Experiment with different positions and see which works best

Why Does Your Body Cool Down During Sleep?

Scientists don’t know why, but cooling down during a night of sleep is thought to be a signal intended for our body to prepare for the deep phases of health-restorative sleep, while a rise in body temperature signals that it’s “go time”. 

Nevertheless, this biological trait is why most of us can sleep better and feel refreshed when waking up. 

Why Do You Radiate Heat at Night?

This happens when your core body temperature peaks. Since your body is heating up, it makes sense for you to radiate heat to surrounding objects and people (see reason 5). 

The reasons we’ve mentioned may be the underlying cause/s of why you seem to emit heat and feel overheating at night. 

Why Does My Body Get So Hot at Night But Not Sweating?

The feeling of getting hot at night is likely attributed to anhidrosis—the opposite of hyperhidrosis. When you have anhidrosis, you feel your body overheating, but you can’t seem to produce sweat.

Caution: If you feel so hot yet can’t sweat, visit your hospital’s A&E room immediately. Anhidrosis is a potentially life-threatening medical condition.

Why Do I Get So Hot When I Sleep on My Stomach?

You might feel hot when you lay on your stomach since your tummy might be sensitive to heat. Since laying on your stomach virtually removes ventilation from your tummy, you feel hot. 

Opt to lay on your back or side and try to see if you stay cool at night. 

What Causes Night Sweats at Night?

Any of the nine reasons we’ve covered may be the underlying cause of getting hot when you sleep at night. Some people may have more than one reason that contributes to their night sweats. 

If you don’t think you have an underlying medical condition that causes night sweats, try lifestyle and sleep environment changes and see if you get better sleep. 

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