Night sweats: causes, effects and what you can do about them

What are night sweats?

Everyone perspires during sleep. A healthy adult loses an average of 0.25 to 0.5 litres of fluid per night, that is perfectly normal and even necessary for regulating body temperature. Night sweats are something different: you regularly wake up with soaking wet nightwear and sheets, even when the room temperature cannot explain it. In clinical night sweats, fluid loss can amount to 2 litres or more per night.

Night sweats occur in both men and women, but the causes differ. Sometimes they are harmless and can be resolved with a few adjustments to your sleeping environment. Sometimes they are a symptom of something that needs further attention.

The causes of sweating at night

Your sleeping environment and mattress

The most solvable cause is also the most underestimated: your sleeping environment. An overly warm bedroom, synthetic bedding or a poorly ventilating mattress together create a kind of greenhouse effect. Sweat does not evaporate, your body temperature keeps rising and your sweat glands keep working.

Mattresses made of memory foam or synthetic cold foam retain heat and breathe poorly. Natural latex works differently: its open cell structure allows air to circulate and actively draws away heat and moisture. That is not marketing, it is material science. For people who consistently sleep too hot, the choice of mattress can make a noticeable difference.

Hormonal causes

Hormonal fluctuations are the most common medical cause of night sweats. In women, the menopause is the best-known trigger: falling oestrogen levels disrupt the thermostat function of the hypothalamus, leading to hot flushes and night sweats. Hormonal shifts during pregnancy and around the menstrual cycle can also cause excessive sweating at night.

In men, testosterone fluctuations (the so-called andropause) play a comparable role, though this is less widely known. Thyroid disorders, whether an overactive or underactive thyroid, can cause night sweats in both men and women.

Lifestyle and external factors

Alcohol disrupts REM sleep and raises the body's core temperature, a combination that strongly promotes night sweats. Stress and elevated cortisol levels activate the sympathetic nervous system, which also increases heat production. Certain medications, particularly antidepressants, cause night sweats as a side effect in 8 to 22% of users. Infections such as flu or COVID can also temporarily trigger night sweats.

When to see a doctor about night sweats

Consult a doctor if night sweats are accompanied by one or more of the following symptoms:

• unexplained weight loss
• persistent fever
• extreme fatigue
• swollen lymph nodes

Occasional sweating without other complaints is almost always harmless. When in doubt, a visit to your GP is always worthwhile.

Night sweats in women: the role of hormones

In women, night sweats are strongly linked to hormonal changes throughout life. The menopause is the best-known cause: more than 75% of women in perimenopause experience hot flushes and night sweats. What many women do not know is that perimenopause, the years before the official menopause, can begin years earlier and is less linear than often thought.

Other female-specific causes include: 

• Pregnancy: night sweats are particularly common during the first trimester and in the weeks after delivery (postpartum).
• Menstrual cycle: during the luteal phase, progesterone drops and body temperature temporarily rises, which can lead to more sweating at night.
• PCOS and thyroid problems: both conditions can disrupt thermoregulation.

Addressing the medical cause requires guidance from a doctor. But adjusting your sleeping environment is something you can do yourself, even while waiting for a GP appointment. A well-ventilating mattress and breathable bedding noticeably reduce symptoms, regardless of the underlying cause.

Night sweats in men

Men are less likely to talk about night sweats, but they are just as real. The most common causes in men are testosterone decline (andropause), sleep apnoea, excess weight and alcohol use. Sleep apnoea in particular is strongly correlated with night sweats and is more frequently diagnosed in men.

Men more often dismiss night sweats as an inconvenience that simply comes with the territory. That is understandable, but not always justified. As with women, night sweats can be a signal, and adjustments to the sleeping environment are a low-threshold first step.

What can you do about night sweats?

A combination of adjustments gives the fastest noticeable result. Start with the factors you can influence directly:

• Bedroom temperature: 16–18°C is optimal for sleep. Turn off the heating before bed and leave a window slightly open.
• Bedding: Choose breathable materials: cotton, linen or bamboo. Avoid synthetic fleece or polyester.
• Your mattress: Memory foam and synthetic cold foam retain heat and draw away moisture poorly. Natural latex has an open cell structure that allows air to circulate. For hot sleepers, this is the biggest lever in the sleeping environment.
• Evening routine: Avoid alcohol at least 3 hours before bed. No heavy meals late in the evening. A cool shower before sleep helps lower body temperature. Ideally, no caffeine after 2 pm.
• Clothing: Light, loose cotton pyjamas or nothing at all.
• Stress: Breathing exercises before bed lower cortisol levels. Magnesium has limited scientific evidence but carries little risk.

Which mattress helps with night sweats?

Mattress choice has more impact on your sleep temperature than most people realise. Here is how the three main mattress categories compare on ventilation:

• Memory foam: poor ventilation. Absorbs heat and releases it slowly. A well-known complaint among hot sleepers.
• Cold foam / polyether: ventilates better than memory foam, depending on quality. A mid-range option.
• Natural latex: open cell structure that allows air to circulate and passively draws away heat. No synthetic compounds, hypoallergenic and no chemical off-gassing.

Tuur® is a Belgian family brand that works exclusively with 100% natural latex. The brand was named best latex mattress by the Consumentenbond. If you consistently sleep too hot and are looking for a new mattress, a natural latex mattress is the most logical choice based on the material properties.