Night sweats: why do we sweat at night?

In many cases, sweating at night is a normal physiological response.

As during the day, the body continues to regulate its internal temperature in order to remain within a temperature range in which it does not need to activate major mechanisms for heat production or heat loss. If this zone is exceeded, even slightly, the sweat glands can be activated. Several factors can cause this rise in temperature during sleep. A bedroom that is too warm, thick or poorly breathable bedding, or unsuitable sleepwear can lead to an increase in body heat, and therefore to nighttime sweating.

Reminder : Sweat primarily serves to dissipate heat and keep the body at a temperature of around 37°C (98.6°F).

Let us also note that thermal regulation varies over the course of sleep cycles. During certain phases, particularly REM sleep, the body's ability to adjust its temperature is reduced. This can promote more pronounced sweating, even in the absence of heat.

Beyond environmental factors, certain lifestyle habits can promote sweating during the night. Diet, in particular, plays an important role. Heavy meals, spicy foods, alcohol , and caffeine can increase thermogenesis, that is, the production of heat by the body. This rise in temperature can persist during the night and trigger sweating. Tobacco is also associated with increased sweating. It stimulates the body to produce adrenaline, a hormone that raises body temperature.

Nighttime perspiration can also have an emotional origin and be linked to activation of the autonomic nervous system, independently of any rise in body temperature. Stress, or even simply nightmares, can trigger night sweats. These can also be associated with sleep disorders, such as sleep apnea, which is characterized by repeated interruptions of breathing during the night, leading to activation of the nervous system and a stress response in the body. Restless legs syndrome can also fragment sleep and promote sweating.

Night sweats tend to become more frequent with age, particularly in women, due to hormonal fluctuations.

Indeed, night sweats are one of the common discomforts brought on by menopause. The decrease in estrogen disrupts thermal regulation by lowering the threshold at which sweating is triggered. Even minimal temperature changes can then be enough to cause hot flashes, often at night. It should be noted that in men, a decrease in testosterone can also be accompanied by similar symptoms, although this is less common.

Certain diseases and medications can also cause night sweats.

Hyperthyroidism, for example, increases basal metabolism, which leads to greater heat production and therefore more intense sweating, including at night. Similarly, in people with diabetes, episodes of nocturnal hypoglycemia can activate the sympathetic nervous system and trigger profuse sweating. Gastroesophageal reflux disease (GERD) is also sometimes mentioned. Although the association is not consistently found in studies, some clinical observations suggest that nocturnal reflux episodes, accompanied by discomfort or pain, can trigger sweating. Antidepressants or certain oral contraceptive pills also appear to be associated with night sweats, but there are still relatively few studies on this topic.

In some cases, night sweats can be associated with more serious medical conditions, although this remains relatively uncommon. Certain infections (tuberculosis, HIV, mononucleosis, endocarditis) may be accompanied by fever and nighttime sweating. Hematologic diseases, such as lymphomas or leukemias, are also associated with night sweats, often along with other symptoms such as unintentional weight loss, fatigue, or persistent fever. However, it is important to emphasize that, in most cases, night sweats are not related to a serious illness.

A medical consultation is nevertheless recommended if night sweats are intense, persistent, or unusual, or if they are accompanied by other symptoms. Otherwise, adjusting lifestyle habits is often enough to improve them.

Several solutions can help address nighttime sweating. In most cases, a few simple, easy-to-implement changes can help reduce night sweats. First, it is important to monitor the bedroom temperature, which should ideally be kept between 64 and 66°F (18–19°C). Likewise, bedding and sleepwear should not trap heat and moisture. For this reason, it is generally recommended to use cotton or linen rather than synthetic fabrics.

Certain evening habits can also be adjusted. Heavy meals, alcohol, very hot drinks, or spicy foods increase the body’s heat production and can trigger night sweats. It is therefore better to limit them in the evening. Finally, stress and strong emotions before bedtime can activate the sympathetic nervous system. Establishing a calming routine (reading, breathing exercises, meditation) can help reduce these episodes.

If nighttime sweating is due to menopause and is experienced as particularly distressing, the physician may prescribe hormone therapy. The goal is to stabilize hormone production and thereby prevent hot flashes and the sweating that accompanies them. Similarly, in cases of hyperthyroidism, treatments aimed at regulating thyroid hormone production help reduce excessive sweating.

While homeopathy may also help with night sweats, it is preferable to seek advice from a healthcare professional before beginning a course of treatment.

Certain plants or dietary supplements have indeed shown beneficial effects in cases of nighttime sweating. A study conducted between 2018 and 2019 involving 163 postmenopausal women evaluated the effect of evening primrose oil (1,000 mg, twice a day for 8 weeks) on hot flashes and night sweats. While no significant improvement was observed for hot flashes, the results did show a significant reduction in the frequency and severity of night sweats in the treatment group compared with the placebo group. These findings suggest a potential effect, although the mechanisms of action remain poorly understood and clinical data are still limited.

• MCCARTHY L. & al. Night sweats: A systematic review of the literature. The Journal of the American Board of Family Medicine (2012).

• BRYCE C. Persistent night sweats: Diagnostic evaluation. American Family Physician (2020).

• OSHVANDI K. & al. The effect of evening primrose oil capsule on hot flashes and night sweats in postmenopausal women: A single-blind randomized controlled trial. Journal of Menopausal Medicine (2021).

• JOFFE H. & al. Sleep and menopause. Menopause (2025).