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  • Sweat produced when you exercise comes from your eccrine glands while sweat produced when you’re stressed or anxious is produced by your apocrine glands
  • “Stress sweat” smells different than “exercise stress” and leads to a heightened state of alertness
  • Men who sniffed women’s stress sweat rated them as less confident, trustworthy and competent

Don't Sweat It

May 07, 2016 | 46,281 views
| Available in EspañolDisponible en Español

By Dr. Mercola

Although many people would rather not sweat, especially when said sweating occurs in the midst of an important social or work-related event, this natural body process is quite beneficial. For starters, sweating helps to prevent your body from overheating because it helps you maintain a proper body temperature.

Your sweat also carries toxins out of your body, assisting in detoxification, cleans out your pores (which helps to minimize acne), and can even help kill viruses and bacteria on the surface of your skin.

The Science of Sweating

You have two different types of sweat glands: eccrine sweat glands, which are distributed over your entire body, and apocrine sweat glands, located on your scalp, armpits and genital area. The primary purpose of eccrine glands is to regulate your body temperature.

As your body temperature rises, your body will automatically perspire to release salty liquid from your sweat glands to help cool you down. This is controlled by your autonomic nervous system, which you cannot consciously control.

However, certain emotions, such as anxiety, anger, embarrassment or fear, can prompt you to sweat more. This — your emotions — is a prime trigger of sweat from your apocrine glands. These glands, by the way, also produce bacteria to break down the sweat, and this process causes body odor.

This is why body odor comes primarily from under your arms — not so much from the sweat that forms on your chest or arms, for instance. In addition, sweat produced from exercise or overheating is made up primarily of water and salt.

Sweat produced when you're stressed also contains water and salt, along with fatty substances and proteins, which interact with bacteria leading to a distinct odor.

Stress Sweat Changes How You're Perceived by Others

Interestingly, the sweat produced from feelings of anxiety is different from that produced by a tough workout.

Sweat produced when you exercise comes from your eccrine glands while sweat produced when you're "sweating over" an upcoming test, presentation or blind date is produced by your odorous apocrine glands.

Not only can people detect the difference between stress sweat and exercise sweat — they may also change their perception of you because of it. In one study published in the journal PLOS One, men who sniffed women's stress sweat rated them as less confident, trustworthy and competent.1

The researchers suggested this may be a helpful nonverbal signal that allows you to communicate with people around you. Study author Pamela Dalton, Ph.D. told New York Daily News:2

"If you're interacting with someone and you pick up on the fact that they're stressed, it might change your interaction. Maybe you'll be a little nicer, maybe you'll move away … It allows us to convey information about our emotional state or health status without actually talking."

Stress Sweat Sharpens Alertness

Stress sweat, it seems, communicates quite a bit to those around you, which makes sense since it's often produced in association with the fight-or-flight stress response. One study had participants inhale sweat collected from men during their first time skydiving or during exercise.

Those who sniffed the stress sweat had a heightened brain response when later looking at faces with different expressions. In other words, they were in a heightened state of alertness. Lead study author Lilianne Mujica-Parodi, Ph.D., told The Wall Street Journal:3

"It enhanced the brain's perception across the board, not only to things that are obviously a threat but also to things that aren't obvious but might be threats."

Other brain changes revealed in response to stress sweat include heightened activity in the amygdala brain region, which processes emotions including fear.4

So sweat appears to exert not only physical benefits but may also communicate beneficial signals to those around you, particularly when the sweat is triggered by emotions like stress.

Why Do Some People Sweat More Than Others?

You're born with anywhere between 2 million and 4 million sweat glands, and the number of such glands you have will determine, in part, how much you sweat. While women generally have more sweat glands than men, men's glands tend to be more active and produce more sweat.5

Further, while most people sweat when their body's temperature rises, everyone is different in how much sweat is released as a result. Your weight also plays a role; overweight people tend to sweat more than those who are a healthy weight.

As mentioned, your level of stress and anxiety also plays a role. Even in cases of hyperhidrosis, which is the medical term for excessive sweating, the sweating tends to be worse when you're under stress and is thought to be triggered by your body's stress response. Johns Hopkins pediatrician Dr. Kate Puttgen told Medical Daily:6

"The cause of primary focal hyperhidrosis is not well understood but is thought to originate from overactivity of the sympathetic 'fight or flight' nervous system sending aberrant signals to the major sweat glands of the body."

Your palms and the soles of your feet have a higher density of eccrine glands than other parts of your body, and while the "why" is still unknown, these two areas tend to be primarily activated by emotional stimuli.

The glands in your armpits are stimulated by both heat generation and emotions, while most other body areas are primarily brought to sweat by heat.

It's possible to sweat excessively from just one area of your body, such as your palms, and while this isn't physically dangerous, it can lead to emotional and social problems for some people.

Be Wary of Blocking Your Sweat With Antiperspirants

Antiperspirants address armpit odor using antimicrobial agents to kill bacteria and other ingredients such as aluminum that block your sweat glands. However, these products may affect the bacterial balance in your armpits, leading to an even more foul-smelling sweat problem.7

Those who used antiperspirants saw a definitive increase in Actinobacteria, which are largely responsible for foul-smelling armpit odor. Other bacteria found living in people's armpits include Firmicutes and Staphylococcus, but the odors they produce are milder, and they're not produced quite as readily.

It turned out the less odor-causing bacteria may be killed off by the aluminum compounds (the active ingredient in most antiperspirants), allowing bacteria that produce more pungent odors to thrive instead. In some participants, abstaining from antiperspirant caused the population of Actinobacteria to dwindle into virtual nonexistence.

This means using an antiperspirant may make the stink from your armpits more pronounced, while quitting antiperspirants may eventually mellow the smell. Not to mention, the idea of blocking your sweat glands isn't typically wise either.

The Benefits of Sweating

Many people focus on the downsides of sweating, but there are quite a few upsides as well. The use of sweating as a form of detoxification has been valued as a form of cleansing since ancient times. According to one systematic review published in the Journal of Environmental and Public Health:8

"Sweating has long been perceived to promote health, not only accompanying exercise but also with heat. Worldwide traditions and customs include Roman baths, Aboriginal sweat lodges, Scandinavian saunas (dry heat; relative humidity from 40 percent to 60 percent), and Turkish baths (with steam)."

The review found that toxins including arsenic, cadmium, lead and mercury are excreted in sweat and noted:

"Sweating is not only observed to enhance excretion of the toxic elements of interest in this paper, but also may increase excretion of diverse toxicants, as observed in New York rescue workers, or in particular persistent flame retardants and bisphenol-A … Optimizing the potential of sweating as a therapeutic excretory mechanism merits further research."

The researchers noted the following promising roles of sweat in detoxification:

  • Sweat may be an important route for excretion of cadmium when an individual is exposed to high levels
  • Sweat-inducing sauna use might provide a therapeutic method to increase elimination of toxic trace metals
  • Sweating should be the initial and preferred treatment of patients with elevated mercury urine levels9

Do You Sweat Enough?

A major organ of elimination, most people's skin is very inactive. Many simply do not sweat enough to reap all of the detoxification and skin-protective benefits. For the latter, sweating leads to a reduction of viable bacteria on your skin surface, which may lower your risk of skin infections.

In fact, one study suggested that people with atopic dermatitis, who have recurrent bacterial or viral skin infections, may be lacking dermcidin in their sweat, which may impair the innate defense system in human skin.10

If you want to sweat more to reap its benefits, virtually any type of intense exercise will prompt you to do so, although exercising in warm weather (or in a heated room, such as in Bikram yoga) will create even more sweating. Interestingly, if you're fit, your body will sweat earlier and easier. This is a benefit, as the sooner you start sweating the sooner your body cools down, and this allows you to continue exercising harder and longer.

You can also induce sweating via a sauna, either traditional or infrared. Infrared saunas are a great option and can significantly expedite the detoxification process. Hyperthemic conditioning, or "acclimating yourself to heat independent of aerobic physical activity through sauna use," appears to also lead to earlier and easier sweating, similar to being fit.

In short, as your body is subjected to reasonable amounts of heat stress, it gradually becomes acclimated to the heat, prompting a number of beneficial changes to occur in your body. This includes a higher sweat rate and sweat sensitivity as a function of increased thermoregulatory control.11

Keep in mind that sweating, especially heavy sweating, will cause your body to lose valuable fluids and electrolytes. Be sure to stay well hydrated if you've been sweating heavily, and replace your electrolytes naturally by drinking coconut water or water mixed with Himalayan salt.

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