What causes night sweats, and how can you prevent them?

Night sweats

Night sweats, or sleep hyperhidrosis, are defined as persistent sweating or flushing that drenches your sheets and/or pajamas, and occurs independently of environmental factors, such as a too-warm bedroom environment.

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Do you regularly wake up stuck to your sheets with drenched pajamas? Night sweats are a common experience for many people, but they don’t always have to be.

There’s much you can do to make your sleeping experience cooler and more, if not completely, sweat-free.

But before you can go about stopping your night sweats, it’s important to first diagnose what’s causing them.

Common causes of night sweats

Night sweats can stem from a variety of causes, some of which are more benign than others.

True night sweats, or sleep hyperhidrosis, are defined as persistent sweating or flushing that:

  • drenches your sheets and/or pajamas,
  • disrupts or interferes with your sleep, and
  • occurs independently of environmental factors, such as a too-warm bedroom environment.

That last part is important, because it can mean the difference between night sweats that are benign and can be done away with fairly easily, vs. night sweats that are typically a symptom of something more serious and take more effort to resolve.

For example, the nocturnal hot flashes and sweating episodes associated with menopause are true night sweats, whereas sweating from sleeping with flannel pajamas during a heat wave can be easily fixed by wearing lighter sleepwear.

Review the list below to see which might explain your situation, and see if what’s keeping you hot at night is cause for concern.

Do you have night sweats?

Not actually night sweats
  • Warm sleepwear or bedding
    Too-warm bedroom temperature
    Temporary illness, such as a cold
Causes of night sweats
  • Menopause
    Hormone imbalances
    Obesity
    Untreated sleep apnea
    Anxiety disorders
    GERD
    Cancer
    Medications
    Hypoglycemia
    Infections
    Idiopathic hyperhidrosis
    Neurologic disorders

Next, we’ll review each of these in turn and explain how they contribute to night sweats.

Not actually night sweats

First, let’s review three environmental factors that can cause sweating in bed, but aren’t recognized as night sweats.

1. Warm clothing or bedding

If you’re wearing flannel pajamas during the summer, or sleeping with multiple layers of heavy bedding, it shouldn’t be a surprise when you wake up sweating.

In fact, it’s actually best for your body to sleep naked to ensure proper thermoregulation. Thermoregulation is a fancy way of saying that your body works to maintain a consistent body temperature.

Your thermoregulation is tied to your circadian cycle: your body naturally cools down slightly while you sleep, and rises slightly during the day to give you an energy boost.

Your body needs to be a bit cooler to sleep, and sleeping naked aids that cooldown process. If you have to wear something, wear only socks.

2. Overly warm bedroom temperature

Just like warm clothing, having your bedroom thermostat set too high can also cause you to sweat at night and interrupt your sleep.

" Sleep experts recommend the thermostat be set to a cool mid-60s degrees Fahrenheit. It’s much cooler than you think! "

3. Illness

When we’re down with the occasional cold or fever, out body’s immune system kicks into high gear to help us recover back to full health. Often, this includes raising our core body temperature, which can lead to night sweats.

In all three of these cases, the night sweats should go away once you change your sleepwear or bedding, adjust the thermostat, or recover from your illness. If your night sweats persist, it may be due to an underlying health condition.

Health conditions that cause night sweats

If you wake up feeling flushed with drenched sheets on a regular basis, you’re suffering from night sweats. Here’s what might be causing them.

1. Menopause

Menopause is one of the top causes of night sweats for women, thanks to hot flashes. Hot flashes occur due to fluctuating hormone levels, which raise adrenaline and body temperature, wakening the sleeper and causing night sweats.

" Menopause is one of the top causes of night sweats for women. "

2. Hormone imbalances

Similar to menopause, where hormonal changes create symptoms like hot flashes, other hormone disorders or imbalances may have sweating or flushing as a side effect.

For instance, the hormone imbalances associated with pregnancy may cause night sweats. Common hormone disorders associated with night sweats include hyperthyroidism, carcinoid syndrome, and pheochromocytoma.

3. Obesity

Being overweight adds insulation that makes it difficult for your body to properly thermoregulate while you sleep, causing night sweats. Obesity is also a risk factor for obstructive sleep apnea, which, left untreated, may be accompanied by night sweats.

4. Untreated sleep apnea

Obstructive sleep apnea is a breathing disorder that momentarily stops breathing during sleep, resulting in a choking, gasping, or snoring sound.

The recommended treatment is CPAP or BIPAP therapy, where individuals wear a mask connected to an air machine while they sleep. Due to the discomfort of wearing the mask, many people don’t stick to their treatment.

Unfortunately, those people are the most at risk of experiencing night sweats.

" One study found that reports of night sweats were three times higher among individuals who didn’t adhere to their PAP therapy as directed. "

5. Anxiety disorders

People with anxiety disorders live with a chronically activated nervous system. Their anxiety isn’t just mental or emotional; it displays in physical symptoms like increased heart rate and night sweats, too.

6. GERD

In addition to heartburn, people with GERD may also experience night sweats.

7. Cancer

Night sweats can be an early warning sign of some cancers, particularly lymphoma, leukemia, prostate, or thyroid cancer.

Although, night sweats won’t exist in isolation. If you have cancer, you’ll likely see other symptoms, too.

8. Medications

Many medications, including antidepressants, over-the-counter anti-fever medications, chemotherapy, and psychotropic drugs, can induce night sweats as a side effect.

9. Hypoglycemia

Hypoglycemia, or low blood sugar, may include night sweats as a side effect. Individuals who take insulin to treat their diabetes often experiences drops in blood sugar during the night, which leads to night sweats.

10. Infections

Night sweats are a common side effect for many infections, including tuberculosis, HIV, and other bacterial infections like brucellosis.

11. Idiopathic hyperhidrosis

This condition affects just under 3% of Americans. It’s characterized by chronic sweating or episodes of heavy sweating with no explicable cause. You’ll note it shares part of its name with the technical term for night sweats – “sleep hyperhidrosis.”

12. Neurologic disorders

Although more rare, some neurologic conditions are associated with increased sweating and night sweats. These include autonomic neuropathy, posttraumatic syringomyelia, storke, and autonomic dysreflexia.

How to stop (or lessen) night sweats

Unfortunately, if you have one of these underlying conditions, you can probably expect to experience night sweats at least occasionally.

There is good news, however. There are many techniques you can try to minimize both their intensity and their frequency.

1. Lower your bedroom temperature.

As we mentioned above, the ideal bedroom temperature is somewhere in the mid -60s degrees Fahrenheit. However, if you’re living with a health condition that makes you run more hot overall, you may need to adjust it a few degrees lower than that to stay comfortable.

2. Get a fan for your bedroom.

Add a breezy feeling to that cooler temperature by sleeping with a bedside fan, ceiling fan, or both.

3. Sleep naked.

The less layers you have on, the less hot you’ll be. Sleeping naked is backed by the science, too – your body can better regulate your temperature, and avoid getting too hot or too cold.

" If you’re uncomfortable sleeping fully in the nude, wear light, loose clothing made of breathable materials. "

4. Use less bedding.

Don’t stop at your pajamas. Sleep with less bedding, too.  For the bedding you keep, opt for sheets made of breathable linen or cotton.  

5. Invest in a cooling mattress.

Some mattresses sleep cooler than others. Stay away from memory foam beds, which tend to trap body heat. Instead, opt for latex, innerspring, or hybrid beds that feature cooling comfort layers made of gel or copper. These bed types also do a better job at distributing heat, maintaining a cooler sleep surface.

For even more cool, top your mattress with cooling mattress toppers and pads, and rest your head on a cooling pillow.

6. Reduce your stress.

It may seem like it has nothing to do with your sleep, but being chronically stressed out puts your nervous system into overdrive. Part of that overdrive response includes raising your body temperature, getting you energized to adequately meet any physical threats.

" By lowering your stress levels overall - during the day and at night - your body can literally and metaphorically “cool down.” "

Give yourself mental health breaks during the day, take up yoga or aromatherapy, and listen to soothing music as part of your bedtime routine.

7. Eat well and exercise.

Just like your clothing, extra body weight adds layers that heat up your body and interfere with your body’s ability to thermoregulate. A healthy diet and exercise routine can help you stay in shape (or lose weight if needed), and the exercise will help reduce your stress levels to boot.

8. Don’t eat spicy foods.

These foods taste hot because they are hot. Avoid these at dinner and in any evening snacks, to avoid them heating up your body before bedtime

9. Don’t drink before bed.

Alcohol can induce drowsiness, but as you sleep the effects of the alcohol wear off. Your body responds with a swift increase in temperature, causing you to wake up earlier than expected and potentially causing night sweats.

10. Keep refreshments by the bed.

Before you sleep, drink a glass of cool water. Keep an ice pack, or ice cubes, on your bedside table so you can quickly cool yourself down if you do wake up. Another alternative is a cooling spray, or a small towel you can dip in cool water to dab on your face and neck.

When it’s time to see a doctor about your night sweats

Most of the time, night sweats go away once a person makes changes to their sleepwear or bedroom environment.

However if your night sweats persist, even after making these changes, it may be time to see a doctor. They’ll be able to diagnose the underlying condition, which will dictate the appropriate treatment.

Before your appointment, keep a sleep diary where you note the frequency of your night sweats and any other daytime and nighttime symptoms. Also include details about your sleep schedule, diet, and exercise regimen. Your doctor will ask these questions, and the sleep diary will make sure you’re prepared to answer them!