Sauna use isn't very common in the United States, save for a few high-end spas. But there is one region in the world where sauna use is as common as showering: Finland!

A converted crop harvester. Source: Daily Mail

A converted crop harvester. Source: Daily Mail

In Finland, saunas are a national obsession. There is, on average, 1 sauna per household in this small Scandinavian country. Watch the quirky documentary Steam of Life to see the funny things that Finns will convert to saunas—everything from abandoned telephone booths to decommissioned crop harvesters.

Scientists have studied the effects of sauna use on our physiology, and the results are pretty convincing—saunas may be both medicine and the ultimate performance enhancer!

Here are 5 incredible things you are doing for your brain when you sit in a sauna.

DISCLAIMER: Sauna use isn't safe for everyone. Make sure your doctor approves your use of a sauna so you don't hurt yourself. I'm not responsible for harm that comes from using saunas beyond their intended or appropriate use.

1. You may be reducing your risk of Alzheimer's disease.

Observational research from Finland has shown that men who used the sauna 4-7 times per week had a 65% reduced risk of developing Alzheimer's disease or other dementia. (R)

Now, this kind of research can't prove causality (it's only a correlation) but there is one thing I'd like to point out: In the States, sauna use is associated with a gym membership and healthy lifestyle. Were this observational study performed in the U.S, it would be hard to say whether the sauna itself was actually doing anything. However, in Finland, sauna use is extremely commonplace. It's not even necessarily a health practice. This strengthens the notion that sauna use was actually mediating the effect seen on practitioners' health.

2. You are helping prevent your brain from becoming a dumping ground for plaque.

When proteins become disfigured, they can clump together. This is the case with beta amyloid, the protein comprising the plaque found in the brains of Alzheimer's disease sufferers. What if we could do something to prevent this accumulation? Enter: heat shock proteins.

Exercise and saunas provide a form of heat stress. Heat stress activates heat shock proteins (HSPs). Think of these proteins as structural reinforcement to other proteins, like the scaffolding on a building. Among their many duties is to prevent beta amyloid from becoming disfigured which can cause it to clump up. (R

3. You may be treating your depression. 

When compared to a sham (fake) treatment, acute doses of hyperthermic conditioning (the scientific term for elevated body temperature) for 6 weeks significantly improved symptoms in people with major depression. (R) Researchers noted that the effect was almost 2.5 times stronger than standard antidepressant treatment compared to placebo. (R) There are many complex mechanisms at play, but one of them likely involves proteins called dynorphins.

Dynorphins are released by sauna use (or extreme exercise) which creates feelings of discomfort. If the term "dynorphin" sounds familiar it's because they're like the inverse of endorphins, those feel-good compounds we all associate with exercise. While unpleasant, a temporary increase in dynorphin helps to increase endorphin receptors (R), thus making you more sensitive to the feel-good effects of exercise or sauna. This is why immediately after a sauna or exercise session, you feel amazing—and the effects become more pronounced with time.

4. You are growing new brain cells.

Exercise is well-known to boost BDNF (brain-derived neurotrophic factor), a major mediator of neuroplasticity. This helps your brain forge new connections, solidify long term memories, reduce anxiety and even heal from early traumatic events. A small study has found that sauna use post-workout helped to increase the expression of BDNF in the brains of subjects beyond exercise alone. (R

5. It might help prevent multiple sclerosis (MS).

In MS, myelin is destroyed by the body's immune system. Myelin is the fatty insulation around neurons that helps transmit thoughts.

Researchers have noted the strange phenomena that whenever women with multiple sclerosis become pregnant, they go into remission. It turns out that the hormone prolactin, which surges during pregnancy, helps to rebuild myelin. (R) But prolactin is present in men also, and is powerfully boosted by sauna use. Men that stayed in a sauna (80 degrees, dry heat) saw their prolactin levels shoot up 10-fold (R), while in another study women experienced a 5-fold boost. (R)

Unfortunately, studies that have tested the effectiveness of heat therapy on patients who have already developed MS have turned up with negative results. In one Finnish study, heat-sensitive patients with MS (heat sensitivity is a common symptom of MS) were subjected to sauna and experienced a temporary worsening of cognitive function. (R) Similarly, another study found that there was a reduction in physical performance in patients with MS. (R) Both effects were related to an increase in core body temperature that was not seen in healthy controls.

6. You are sharpening your focus and enhancing your memory.

When you heard about the attacks on 9/11, what were you doing? I bet you can remember your exact circumstances in perfect clarity. This is owed to a neurotransmitter called norepinephrine, which helps you focus and store strong memories during emotional stress. But, emotional stress isn't the only stimulus to cause a robust increase in norepinephrine.

Physical stress, like from heat or exercise, causes a surge of norepinephrine as well. One study found that when men sat in a sauna that was heated to 80°C (176°F) until subjective exhaustion, their levels of norepinephrine increased three-fold. (R) Another study in women saw a similar (albeit less pronounced) boost. (R) The takeaway? Use saunas (or exercise) to boost "norepi" next time you need to "refocus."