Night sweats: causes and what helps

You wake up drenched in the middle of the night, push the duvet off, flip the pillow, and try to fall asleep again while your body alternates between boiling and freezing. For many women in menopause, this is a familiar experience. Night sweats are one of the most common symptoms, and they are often what affects daily life the most, not because the sweating itself is dangerous, but because it ruins sleep.

Why do you sweat at night?

Your body has a built-in thermostat located in the hypothalamus, a small part of the brain. This thermostat has a comfort zone, a temperature range where the body neither needs to warm up nor cool down. In healthy women before menopause, this window is approximately 0.4 degrees wide. In women with night sweats, this window narrows to close to zero degrees.

That means even the slightest change in body temperature, such as the natural cooling that occurs during deep sleep, is enough to trigger the body's emergency cooling. Blood vessels in the skin dilate, sweat glands activate, and the heart rate increases. The body reacts as if it is overheated, even though it is not.

This change is caused by oestrogen deficiency affecting specialised nerve cells in the hypothalamus that are normally kept in check by oestrogen. Without that brake, these cells become overactive and hypersensitive to temperature changes. It is a sophisticated biological mechanism, not something you can control with willpower.

How common is it, and how long does it last?

The answer to the first question is: very common. Around 80 per cent of Norwegian women experience a period of hot flushes and night sweats during menopause. For roughly 20 per cent, symptoms start as early as five to ten years before the last period, and the prevalence rises to around 40 per cent at the time of menopause.

Duration is the question most people ask, and the answer is unfortunately that it varies widely. The SWAN study, which has followed women through menopause over many years, found that vasomotor symptoms typically last between 5 and 13 years. Women who get symptoms early, already before the last period, often have the longest duration, with an average of 9 to 10 years. Women who first get symptoms after menopause have a shorter duration, with an average of around 3.5 years.

It is important to say that symptoms gradually diminish for the vast majority. The first years are usually the worst, and then the episodes become less frequent and milder over time.

When it is not menopause

Although night sweats at this age are usually caused by hormones, there are other causes that should be considered. Low thyroid function can produce similar symptoms, and up to 20 per cent of women with menopausal complaints may have an underlying thyroid problem. Certain medications, especially some types of antidepressants, can also cause night sweats. In rare cases, night sweats can be a sign of lymphoma or infections.

Contact your doctor if the night sweats are accompanied by unexplained weight loss, persistent fever, swollen lymph nodes, or other symptoms that do not fit with menopause. A simple blood test can rule out most other causes.

What can you do?

There are several approaches with documented effectiveness, from simple everyday measures to medical treatment.

Your bedroom is a good place to start. Keep the temperature between 17 and 18 degrees Celsius. Use bedding in natural materials such as cotton, linen, or bamboo, which breathe and transport moisture better than synthetic fabrics. A lightweight duvet with a low tog rating provides better air circulation. Have an extra set of bedding available for the worst nights, so you do not have to lie in wet clothing.

Hormone therapy is the most effective treatment available for night sweats. A review of 21 studies with over 2,500 participants showed an average reduction of 77 per cent in the frequency of hot flushes compared with placebo. Most women notice improvement within four weeks of starting. Talk to your doctor about whether this is an option for you.

Cognitive behavioural therapy, specifically adapted for menopausal symptoms, has been shown to reduce the perceived burden of night sweats. It does not necessarily change the number of episodes, but it changes how you relate to them, which can have a surprisingly large effect on sleep quality. This approach is recommended by several international professional bodies and can be completed in just four to six sessions.

Night sweats and the day after

What makes night sweats so burdensome is not only what happens at night but the knock-on effects the next day. Fragmented sleep disrupts deep sleep stages and REM sleep, which are essential for memory, mood, and immune function. Research has revealed a surprising finding: women with night sweats showed poorer cognitive function even when they slept long enough. The sleep was there, but the quality was not good enough.

This connection between night sweats, poor sleep, and daytime function is important to understand, because it means that treating night sweats is not just about sleeping better at night. It is about functioning better during the day, at work, in relationships, and in everyday life.

The key takeaway

Night sweats are common, they have a clear biological cause, and effective help is available. Start with the practical measures you can take tonight, and talk to your doctor if the symptoms are troublesome. You do not have to accept that your nights will be like this for years. There are solutions, and they can make a big difference.