When to worry about night sweats

What are night sweats?

Getting hot and sweaty in the night because your bedroom is too warm or duvet is too thick is normal. Night sweats are when you sweat so much that your night clothes and bedding are soaking wet, even though where you're sleeping is a comfortable temperature.

Night sweats are not related to your sleeping environment and they happen independently of outside temperature. It's important to check whether your night sweats could be a problem, or if you just need to change your sleeping conditions.

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Night sweats

We all sweat when we get hot. It's one of our 'homeostatic mechanisms' - the ways our bodies are adapted to maintain the same constant internal environment. This is very important to allow all the processes going on inside our bodies to tick along smoothly. Sweating helps your body lose heat by evaporation if your core temperature, deep inside your body, rises. In the same way, shivering or shutting down the circulation in your hands and feet helps warm your body up if you're cold. But sometimes sweating, especially if the outside temperature isn't hot and you're not wearing too many layers or exercising hard, can be a sign that there's something going on.

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What causes night sweats?

Night sweats have many different causes - some of the most common are:

Very rarely night sweats can be a sign of a more serious underlying medical condition, including some cancers.

• Night sweats and menopause - for women over 40, night sweats are often caused by hormonal changes from the menopause and perimenopause. Around 85% of women have hot flushes at the beginning and during menopause.

• Anxiety and night sweats - anxiety can lead to night sweats when your body reacts to stress - such as when you're scared from a bad dream.

• Blood sugar and night sweats - low blood sugar can make the body produce too much adrenaline, which in turn can lead to night sweats. This is a common problem in those with diabetes, and can also happen if you've drunk too much alcohol before bed.

• Medicine and night sweats - certain medicines can cause night sweats. Some medicines such as SSRIs, those for diabetes, or hormone treatment, list sweating as a potential side effect.

What infections cause night sweats?

Some infections can cause night sweats - including tuberculosis and HIV. However, sweating is just one symptom of these conditions and on its own does not signify anything specific.

You may get sweats from fever associated with colds and flu. If you are unwell, seek advice from a doctor.

Hyperhidrosis

Hyperhidrosis is the clinical word for excessive sweating - during the night or day. This can be a condition in its own right, and doesn't have to be a symptom of something else.

When to see a doctor about night sweats

There are several possible causes of night sweats - and no easy way of differentiating one type of sweating from another. However, doctors will want to rule out more serious causes such as cancer first if this is indicated from the consultation, and then move on to less serious conditions.

To see what is causing your night sweats, your doctor will look at your medical history, and may examine you to see if there is an underlying medical condition. Depending on their findings, they may do further tests such as blood tests or X-rays.

While occasional night sweats are usually nothing to worry about, you should see your doctor if they do not go away, especially if they are every night.

Night sweats and HIV

If you have been diagnosed with lymphoma or HIV, night sweats with unexplained weight loss may be a warning sign that your condition is getting worse.

Menopause

If your night sweats are due to the menopause, you should speak to your doctor about your hormone replacement therapy (HRT) - and, if you are not taking HRT, then look into whether this may help you.

If your doctor thinks your medicine could be causing your night sweats then they can look at prescribing something different.

How to prevent night sweats

Most of the time lifestyle changes will help treat your night sweats.

One of the most effective ways of stopping your night sweats is by making sure your sleeping environment is in the best state it can be, to help you get a good night's sleep.

Certain foods and drink may cause you to sweat at night or have an uncomfortable sleep.