Ah, the sauna. It's fun for the whole family, a fantastic way to relax with friends, and all with a host of amazing health benefits to boot! "Stop heart attacks, flush toxins, zap stress" et cetera, et cetera... You may have seen various collections of these advantages before. As much as I love the sauna, and enjoy reaping the perks for myself, there seems to be an unfortunate amount of misinformation happening in the sauna community when it comes to the health effects. People love to tote the incredible detoxifying, weight loss, pore cleansing magic of the sauna, but some of these claims are exactly that; incredible.
Join me for this first post in a series of articles in which we take a deep dive into some reputable research, scour some studies, and relearn some human anatomy to understand the science behind the statements. We'll take a fine comb through the sauna health claims and ultimately try to separate the myths from the maxims and find which "facts" are actually false.
Quick disclaimer: I am not a doctor, and I am not trying to con you into thinking that I am. Please consult your doctor with any concerns for your specific circumstances. I am also not a scientist, or a professional researcher, so please do your own looking around, and let me know in the comments if you disagree with anything I say. I love saunas, but I love sharing the truth even more.
Some of this will be a review of basic human anatomy, but hey, that's part of the fun! With all that out of the way, let's go!
1. "Saunas Increase Blood Circulation"
"Increased blood circulation" is a common claim in the sauna community. Let's first define circulation, followed by the statement, and finally look into how exactly saunas affect it.
Your body's circulatory system is a network of arteries, vessels and capillaries that carry blood to and from your heart to every corner of your body.  Having low circulation can cause issues that stem from your cells not receiving enough oxygen and/or nutrients. For example, your hands and feet could feel cold or numb, and your skin could appear a bit blue in affected areas if you have light-colored skin.  Poor circulation can also cause more serious issues as a result of weakened or dying cells. Not fun.
So, getting improved blood flow in your body is a good thing which helps to get all those tasty nutrients to your cells. Nice!
Since the body is a closed system, and no blood can be suddenly added to the system when you want to increase the amount of blood flow, you can only increase circulation by either restricting blood flow to certain areas to allow a larger amount in others, or by increasing the rate at which your blood flows through the body in general.
Since most of us aren't manually using tourniquets on our arms to try get better circulation in our feet, saunas must be employing the method of increased flow rate.
So how exactly do saunas improve circulation in your body?
Short answer: By exposing you to fluctuating temperatures, and making your body react to it like an anatomical game of Monkey-in-the-Middle.
Long answer: Increased circulation is actually a side effect of your body's thermoregulatory system trying to keep your core temperature stable in the hot environment of the sauna and the relatively cool environment when you get out of the sauna.
As your core body temperature  begins to rise, the hypothalamus attempts to regulate the temperature through 2 methods:
- Vasodilation: The body begins to channel blood away from the core by dilating, or enlarging, the blood vessels near the surface of the skin. The core is hot, so the outward moving blood carries some of that heat with it. Near the surface, the body can release the heat from the blood through radiation, and if needed...
- Sweating: As your body senses that it can't cool quickly enough by vasodilation and radiation alone, sweat begins to release from your pores and beads up on your skin. As the sweat evaporates, it takes away energy in the form of heat from the surface of your skin causing a cooling effect.
The combination of these techniques cools your blood, which circulates back to the core to be replaced by more hot blood. Your heart will also pump faster to increase the flow of blood. After a number of repetitions, your body will cool down enough to be back within it's comfortable operating range.
Likewise, when you exit the sauna, your body becomes exposed to a much less-hot environment. This is good. It will give your body a break from trying to be the equivalent of a fleshy A/C unit, and the cool air will also allow the body to more efficiently get rid of all the extra heat. Radiation will work better in the cool air, so you'll stop sweating before long.
Eventually, your body will cool down enough that vasodilation will cease, and your body will go back to business as usual.
However, if you stay outside too long, your body might need to begin trying to conserve and maybe even maybe decide to try make some more heat. This happens in 3 ways :
- Vasoconstriction. The opposite of vasodilation. Your body makes the blood vessels near the skin narrower, which decreases blood flow near the outside of the body. Containing heat near the core and vital organs.
- Thermogenesis. Your body can produce heat in various creative ways. For example, it can twitch your muscles rapidly to create some heat. This is also known as shivering.
- Hormonal Thermogenesis. Your thyroid gland will release hormones to increase your metabolism. This will create more energy, and increase heat production.
So there you have it. Saunas do indeed increase blood circulation. Blood flow increases towards the skin and back when you're in the heat, and it is conserved to the central organs as you cool down. Your heart rate also fluctuates up and down as a part of the process.
The average sauna user alternates between hot and cold a few times before calling it a day. This cycle gives your thermoregulatory system a good workout, and will help spread oxygen and nutrients to cells along the way.
2. "Saunas Make You Heal Faster"
Directly caused by the increased circulation, it has been said that saunas help your muscles and other injuries heal faster. How does that work? Let's find out.
Like we learned above, saunas heat up your body and make it work hard to maintain a safe core temperature. This causes increase circulation of blood around the body. We also know that blood carries oxygen and nutrients to your cells. Oxygen and nutrients are necessary for your cells to live, grow, and repair themselves.
Picture the circulatory system as a railroad providing food and reinforcements to the Allies on the front lines in France during World War 2. There is a very long train track, and a single steam train that runs once per day to the front lines and back. That's great! Sure, but that train can only carry so much food and other helpful stuff. The train will eventually deliver food to all of the troops, but if the train is too slow, the Résistance might get weak while they wait, or even die of starvation! C'est pas bien!
To avoid this, the army can increase the number of runs that the train does every day. Eventually, they reach a pace that sufficiently supplies the troops. The brain acts as the Army's logistics manager in this analogy. It automatically adjusts the heart rate to maintain enough supply of fresh blood to the cells while spending the least amount of energy.
Oh look, here comes General Sauna! Gen. Sauna suggests to the logistics manager that he can upgrade all of the trains from steam engines to diesel-electric locomotives. These are much faster, and will get to the front lines and back in half the original time! The trains can deliver many more supplies to keep the soldiers fit and healthy!
If you're anything like me — dense as a packet of rations — my analogy might not suffice. I'll leave links to all my research down below so the more studious of you can learn some more.
The sauna can certainly improve blood circulation by causing your body to exercise it's temperature regulating systems. As your heart rate increases, and your veins dilate, your body can more effectively carry oxygen and nutrients to all the places that need it. Saunas can help your body keep cells healthy, and can improve the healing process for damaged cells.
Join me next time as we dive into how exactly the sauna can help you achieve a glowing complexion, and some other skin related effects. Maybe we'll unmask some myths along the way.
 How does the blood circulatory system work?
 How to Improve your circulation.
 How is body temperature regulated and what is fever?
 How does thermoregulation work?