No one likes when their face is too damp to apply makeup on summer mornings or when it seems like every white shirt you own is permanently discolored, but sweat is actually the body's (pretty brilliant) built-in cooling system. Your body temperature rises, your nervous system gives your sweat glands the green light, and moisture pops onto your skin, where it promptly (well, eventually) evaporates, cooling you down in the process.
And yet, we're constantly at battle with our sweat: trying to make it stink less, trying to stop it altogether during an important meeting, then trying to lose buckets of it at the gym. But if you stop and pay attention, all that perspiration can actually teach you a surprising amount about yourself and your health. Here are a few things it's trying to tell you.
1. You're pregnant...or hitting menopause
Anything that toys with your endocrine system (your body's collection of hormone-producing glands) can leave you feeling sweatier than usual. Of course, there's the dreaded hot flash, which as many as 85% of women have in the years right around menopause, but pregnancy may also be to blame. That's because hormonal changes seem to mess with the brain's "thermostat," mistakenly making you think you're overheating—and triggering the naturally cooling sweat response—even when you've positioned yourself right in front of the AC.
More from Prevention: 8 Ways To Make Menopause Less Miserable
2. You're stressed
If you keep catching yourself sniffing and wondering, "Is that me?", take a second to reflect on what's been on your mind lately. If you're stressed or anxious, your pits are probably to blame. The sweat we produce when we're hot is made by eccrine glands all over the body and contains mostly water and salt. But when we're stressed, sweat is produced by apocrine glands, which are found only in certain areas like the armpits. That type of sweat contains fat and protein that mix with the bacteria on our skin, producing a stench in the process. Same deal if you're anxious or scared.
3. You're spreading happiness...
...or fear. Oddly enough, the people around you can pick up on what you're feeling by the smell of your sweat. In a (rather revolting) experiment, 36 women smelled sweat samples of 12 men who had watched videos meant to either scare them or make then happy. When a woman smelled sweat from a guy who'd been scared by the video, she was more likely to make a facial expression resembling something like fear. When she smelled sweat from a happy guy, she was more likely to smile. Guess it can't hurt to crack a smile at the gym.
More from Prevention: If You're Happy And You Know It, Here's How Your Health Is Definitely Going To Show It
4. You're at risk for heatstroke
Everything's going swimmingly during your summer walk, when suddenly you realize you've stopped sweating and you're starting to get dizzy. Anhidrosis, or the inability to sweat normally, can be dangerous, since it prevents your body from naturally cooling off. If you continue on without rehydrating, you risk heat illnesses like heat exhaustion or heatstroke. Move to a shady or air-conditioned space and have something cool to drink (without caffeine or alcohol). If you don't start to feel better quickly, call for emergency medical attention.
However, longer-lasting anhidrosis may be due to nerve damage, certain medications, or an inherited condition, which can increase risk for heat illnesses and heart problems, too, says David M. Pariser, MD, former president of the American Academy of Dermatology. It's pretty rare, though, he says; just because you don't feel moist and clammy, doesn't mean you're truly not sweating. Turns out, most of us produce about an ounce and a half of sweat every day, not counting those puddles you make when you work out. If you notice a real drop in your sweat production, be sure to bring it up with your doc.