It's 2:47am. You're awake, the pillow is damp, your top is stuck to your back, and the doona has been kicked to the floor for the second time tonight. By the time you've changed and lain back down, you're cold. Then you're hot again. If that's your week, you're not imagining it and you're not alone. This guide covers what actually causes night sweats, what helps, and how to tell when it's a job for your GP rather than for a better pair of pyjamas.
What counts as night sweats
Everyone sweats a little at night, especially under a heavy doona in a Queensland February. Night sweats are different: sweating heavy enough to wake you, dampen your sleepwear or sheets, and happen even when the room isn't especially warm. The repeating pattern matters more than any single bad night.
It also helps to separate them from hot flushes. A hot flush is the sudden wave of heat itself, usually felt in the face, neck and chest. A night sweat is the soaking that can follow. The two often travel together, but not always. We untangle them properly in hot flushes vs night sweats.
What causes night sweats
Your body's thermostat sits in a part of the brain called the hypothalamus. Normally it tolerates a small band of temperature before it reacts. Many causes of night sweats narrow that band, so a tiny rise in core temperature sets off the full cooling response: blood vessels open, sweat pours, and you wake up drenched.
Perimenopause and menopause. By far the most common cause for women from their late 30s onwards. Fluctuating oestrogen makes the thermostat jumpy, and the sweats often cluster in the second half of the night. If you're also waking at the same hour every night, see why menopause insomnia keeps perfect time.
Postpartum hormone shifts. In the weeks after birth, the body sheds fluid and hormones drop sharply. Drenching nights are common and usually settle on their own. More in postpartum night sweats.
The days before your period. The same hormonal swing, on a smaller and monthly scale. Some people notice a few sweaty nights in the lead-up to bleeding, which is worth tracking if it's new. We explain why in night sweats before your period.
Medications. Some antidepressants, hormone treatments, diabetes medicines and steroids list sweating as a side effect. Never stop a medication on your own; raise it with the prescriber.
Alcohol, spicy food and late heavy meals. Alcohol widens blood vessels and disrupts temperature control in the back half of the night. A glass of red at 9pm can show up as a damp pillow at 3am.
Stress and anxiety. Adrenaline and sweat are old friends, and worry about the sweats can feed more of them. We wrote about the 3am panic-and-sweat loop for exactly this.
Illness and other conditions. Infections, fever, an overactive thyroid, low blood sugar overnight and sleep apnoea can all cause sweating. Men get night sweats too, often for reasons nobody mentions; see night sweats in men.
A bedroom that's simply too hot. Not technically night sweats, but it feels the same at 3am. A heater left on, a doona rated for Tasmania, a partner who runs warm. Rule this out first, because it's the cheapest fix.
How to stop night sweats, or at least sleep through them
You can't always switch off the cause, especially a hormonal one. What you can do is give the heat somewhere to go and stop the sweat from sitting on your skin.
Cool the room, not just you. Most people sleep best somewhere around 18–20°C. A fan moving air across the bed helps sweat evaporate, which is how your body actually sheds heat. Our breakdown of fans vs air con covers which works when.
Layer the bed so you can adjust it. One thick doona is all or nothing. A light quilt plus a sheet lets you shed a layer half-asleep. See the hot sleeper's guide to bedding.
Keep a change kit by the bed. A spare top, a small towel and a glass of water. The goal is to get dry and back to sleep in under two minutes, not to turn on the light and fully wake up.
Watch the evening triggers. Alcohol, a hot shower right before bed, and a late heavy dinner are the usual suspects. Change one at a time for a week so you can tell what actually made a difference.
Track it. A note on your phone with the date, rough time, and what you ate or drank is far more useful to a GP than "it's been bad lately".
Why what you sleep in matters
When you sweat, the fabric against your skin decides what happens next. Polyester and heavy cotton hold moisture, so you lie in it, then get cold as it cools. That damp-then-cold cycle is what turns one hot flush into an hour of broken sleep.
Fibres like TENCEL™ Modal absorb moisture and release it quickly, so sweat moves off your skin and the fabric dries faster. That's the logic behind our cooling pyjamas and the Short PJ Set. If you're comparing options, our buyer's guide to pyjamas for night sweats and night sweats and menopause guide go into the detail.
The honest bit
No pyjama stops a night sweat. Not ours, not anyone's. If hormones are the cause, fabric changes what happens after the sweat, not whether it happens. For many people that's the difference between waking once and waking four times, which is worth a lot. But if your sweats are frequent and wrecking your sleep, the biggest lever is usually a conversation with your GP about the cause, including treatment options for perimenopause. A good pair of pyjamas is the support act, not the headliner.
When to see your GP
Book an appointment if your night sweats are new and unexplained, happen most nights, or come with any of these: unexplained weight loss, fever, ongoing fatigue, swollen glands, a persistent cough, or pain. These are uncommon causes, but they're a doctor's job, not Google's. Our red-flag guide to night sweats lists what to mention.
General information only, not medical advice. If night sweats are frequent, severe, or accompanied by other symptoms, please speak with your GP.
