Night sweats: definition and meaning
Night sweats are episodes of heavy sweating during sleep, enough to soak your nightclothes or sheets, that are not caused by a hot room or heavy bedding. Common causes include perimenopause and menopause, the drop in estrogen before a period, infections, some medicines, anxiety and low blood sugar. They are the night-time version of hot flashes.
Why hormones cause night sweats
Estrogen helps steady the brain's thermostat in the hypothalamus. When estrogen drops or swings, the thermostat narrows, and a small rise in body temperature triggers a sudden flush and sweat. That is why night sweats are common in perimenopause, just before a period, after giving birth and during treatments that lower estrogen.
| When | Why |
|---|---|
| Before a period | estrogen and progesterone fall; basal body temperature is already higher in the luteal phase |
| Perimenopause and menopause | bigger, less predictable estrogen swings |
| After birth | estrogen drops sharply; the body sheds extra fluid |
| Medicines | some antidepressants, GnRH agonists, letrozole |
Night sweats, sleep and mood
Waking soaked and cold several times a night fragments sleep, and poor sleep turns up irritability, anxiety and low mood the next day. This is one reason perimenopause mood can feel so heavy. See hot flashes and sleep and mood across the cycle.
What helps
- Keep the bedroom cool; use layers you can throw off.
- Choose breathable cotton or moisture-wicking nightwear.
- Limit alcohol, spicy food and caffeine in the evening.
- Treatments like HRT are very effective for menopausal night sweats; some non-hormonal options exist too.
See a doctor if night sweats come with fever, unexplained weight loss, a persistent cough, swollen glands or extreme tiredness, or if they are frequent and you don't know why.
Frequently asked questions
Are night sweats normal before a period?
Mild night sweats before a period are fairly common, especially from your late 30s onward.
Can night sweats be an early sign of perimenopause?
Yes. They can start while periods are still regular, often alongside sleep changes and mood shifts.
Sources
This page is for information only and isn鈥檛 medical advice. If something worries you, please talk to a doctor.
Keep reading
Hot flashes: definition and meaningHot flashes (hot flushes) are sudden waves of heat, usually around menopause. What causes them, how long they last, what helps, and how they affect mood.Perimenopause: definition and meaningPerimenopause is the transition before menopause when hormones fluctuate and periods change, usually starting in your 40s. Signs, mood changes and timing.
Why do I feel hot before my period?Feeling hot before your period is common. Progesterone raises body temperature after ovulation, and falling estrogen can bring night sweats. What helps.Perimenopause symptoms: the full list, and what helps each onePerimenopause symptoms explained: cycle changes, hot flushes, sleep, mood, brain fog and body changes, with what helps each one and when to see a doctor.Sleep and your menstrual cycle: how they shape your moodHow sleep and the menstrual cycle affect each other and your mood: why sleep worsens before your period, how it fuels PMS, and what helps you rest.