Sweat can tell a lot more about your health than just showing that you are properly hydrated (read our article on 10 Signs You’re Dehydrated here). Sweating is a naturally healthy way to rid yourself of toxins, clean the pores of your skin and keep you cool on a hot day.

Sweating is a sign of a healthy body. Also, it is a good sign that you are burning fat in aerobic exercise. Sweating means that you should hydrate. An excessive amount of sweat can mean a fever. Having less sweat can mean dehydration. These are a few sweat-related health facts that most of us know. Here’s one that you might not know.

Babies that cry are experiencing some distress and when that happens, they sweat. By the age of three weeks, water loss from the palms of an infant was as much as that of an adult would experience.

Here’s What Your Sweat Says About Your Health

1. Sweat can reveal the health of many bodily functions

Doctors frequently use the blood levels of electrolytes and other substances to test for healthy levels of body functioning. By using these four biochemical measurements, health professionals can check for kidney function, dehydration, muscle fatigue, management of diabetes and more.

2. Sweat can reveal if you have anxiety

Most people sweat when they are feeling a “fight or flight” response to a fearful stimuli. People who experience chronic anxiety sweat in small amounts in response to perceived threats in their environment.

Researchers studying the perception of choice and reducing anxiety used finger sweat print as a measurement of anxiety levels. The group who was given a choice of taking a test in any order had reduced sweat amounts than those who did not get a choice.

3. Sweat might mean that you’re lying

Lying isn’t necessarily part of your physical health but it could help with understanding more about your psychological health. Lying often produces similar sweat responses as being anxious does, because the brain knows that the words spoken do not match the event as it happened in the mind. The difference between the two creates stress and can cause sweating.

Lie detectors often use skin conductivity to test for the amount of or presence of sweat. On a more personal level, we can learn to sense when we are sweating and identify if we are lying to ourselves about our shortcomings. Believing a lie that we tell ourselves is often the beginning of a mental health problem.

4. Sweat can signal to potential romantic partners how healthy you are

Hormones are naturally secreted in your sweat as pheromones, which can be detected by smell. When you are a healthy male or female, you send out sweat pheromone signals to potential mates. These pheromone signals can tell a man if a woman is fertile or not and they may also send signals of a woman’s receptivity to sex.

You can read more about how pheromones help attract a mate in our article 5 Things That Make a Woman Beautiful (Besides Her Looks). Both men and women who use synthetic sweat pheromones reported an increase in being approached by the opposite sex over those who did not use the pheromones.

5. Sweat can determine hair growth

Again, crime show enthusiasts know that the human hair can be used to show markers for use of drugs because the shaft acts as a timeline of when drugs came into the body. However, a recent study has shown that it is actually sweating that plays a role in how the drugs get into the hair shaft in the first place. When sweat is secreted at the follicle, it is likely incorporated into the hair shaft.

This sweat and hair data that is collected from a patient provides drug use information that can be used in addiction treatment facilities, by law enforcement, or by health professionals who are doing deeper analysis of bodily functions for a patient. This is true for both illegal drugs and prescription pharmaceuticals.

Sweat band detection devices will likely soon be incorporated into personal wearable fitness trackers. According to some, future applications for wearable sweat data devices could “diagnose a heavy metal poisoning. They will warn a person that they’re in a severe enough depressive state to warrant medication and signaling that the body is getting an infection.”