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The Ancient Health Hack That Cuts Heart Attack Risk, Relieves Stress, and Heals Your Body.

September 22, 2024

What happens when humans sit in a 180-degree room for 20 minutes several times a week?

Really good things, actually.

Regular saunas have been shown to lower blood pressure, reduce the risk of heart attack and stroke, and linked to a decreased risk of dementia, according to a recent paper from researchers in Finland and the U.K. And that’s just for starters.¹

But this isn’t a new finding: Scientists have been reporting on the health benefits of “sauna baths” since the 1950s (at least).²

The question is: Why are saunas good for you, and what are you supposed to do with this information? (Especially if you don’t have a sauna on your back patio.)

In this article, I’m going to give you the science of why “passive heat therapy” (that’s what scientists call it) is so effective, and how you can benefit even if you never step foot in a traditional sauna.

Why Passive Heat Therapy Works: Part 1

When it comes to passive heat therapy, many of the health benefits aren’t exclusive to traditional saunas. You can get them from infra-red saunas and from soaking in a hot bath or jacuzzi.

That’s because passive heat therapy mimics some of the cardiovascular effects of physical activity—even though you’re not moving.

When you expose your body to heat, your heart rate and blood flow increase—in a good way, much like what happens during moderate exercise.³ (You should still exercise if you’re able, but heat therapy is a viable substitute for those with mobility issues or who can’t engage in regular physical activity.)

As a result, passive heat therapy helps lower blood pressure and keeps your blood vessels functioning well, which is likely why it’s been linked to reducing the risk of death from heart disease and stroke.

The increase in circulation also helps deliver oxygen and nutrients throughout your body, supporting overall physical and mental health.

More Benefits of Passive Heat Therapy

From activating your body’s internal repair systems to boosting your mental clarity and energy levels, the potential benefits of heat therapy are impressive and wide-ranging.⁴

Promotes detoxification: Sweating is a natural way for your body to eliminate toxins, and regular heat exposure can support this process, helping to flush out harmful substances and keep your body running smoothly.⁵

Lowers inflammation: Regular heat exposure helps lower C-reactive protein (CRP) levels, a protein that signals inflammation in the body and is linked to conditions like heart disease, diabetes, and autoimmune disorders.⁶

Improves insulin sensitivity: By enhancing your body’s ability to absorb glucose, heat therapy can help lower the risk of type 2 diabetes or assist in managing existing diabetes.⁷

Triggers release of endorphins: Your body’s natural mood enhancers and pain relievers.⁸

Why Passive Heat Therapy Works: Part 2

In a recent study in Frontiers of Public Health, scientists wrote: “Traditional Finnish sauna has been used for thousands of years for leisure, relaxation, and wellness to reduce the stress of everyday life.”

But here’s the twist—while sauna helps you relax, it also gives your body a small, controlled dose of stress that’s actually good for you. This process, known as hormesis, is another way heat therapy works its magic.

By exposing your cells to mild stress, it trains them to adapt and become more resilient. In other words, heat therapy helps your body handle stress better in the long run by making it stronger and more prepared for future challenges.

Why Passive Heat Therapy Works: Part 3

One of the main mechanisms activated by heat therapy is the production of Heat Shock Proteins (HSPs)—named because they were first discovered when cells were exposed to heat stress.

When your body experiences elevated temperatures, HSPs act as “molecular chaperones,” protecting proteins from damage, repairing minor issues, and clearing out proteins that are beyond repair. This process ensures your cells stay healthy and function properly.

At the same time, heat therapy triggers autophagy, a cellular clean-up process where old, damaged components are broken down and recycled to make way for healthier ones.

Together, these processes—hormesis, Heat Shock Protein production, and autophagy—help support cellular repair, improve recovery, slow down aging, and enhance your body’s resilience. So, while the heat may feel intense, it’s doing much more than just helping you relax; it’s making your body stronger for the long run.

The Brain Benefits of Passive Heat Therapy

Heat therapy may also be good for your brain. It helps increase the production of brain-derived neurotrophic factor (BDNF), which supports the growth and maintenance of your brain cells.

Recent research shows that when people experienced whole-body heat (like in a sauna), their circulating BDNF levels went up significantly compared to when only their legs were heated or when no heat was applied.⁹

This is exciting because higher BDNF levels are linked to better brain function, improved memory, and protection against age-related cognitive decline.

Bring the Heat into Your Daily Routine

Now that you know why passive heat therapy can be so beneficial, the next step is figuring out how to make it part of your everyday life.

► Traditional Saunas

Saunas are perfect for boosting circulation, relaxing muscles, and giving your cardiovascular system a mini workout.

Your Sauna Protocol

Aim for a temperature of around 170 degrees Fahrenheit (76.7°C).
Start slowly with 5-10 minute sessions and gradually build up to 30 minutes.
Ideally, use the sauna 4-5 days per week, with 1-2 sessions per day.

► Infrared Saunas

If you’re short on time or prefer a lower temperature, infrared saunas are a fantastic option.

Infrared saunas work by using infrared light to heat your body directly, rather than heating the air around you like traditional saunas do. The infrared light penetrates your skin and heats your tissues from within, allowing for lower air temperatures (typically between 120°F and 140°F, compared to traditional saunas that can reach 180°F or higher).

The direct heat creates a similar sweat response and activates many of the same physiological benefits, such as increased circulation, detoxification, and relaxation.

This means you can stay in longer—about 20-45 minutes—because the lower temperatures are more comfortable, though you can still experience the benefits without needing to stay in as long as with traditional saunas. They’re also more compact, making them a convenient at-home option.

My favorite infrared sauna is made by Sunlig hten. What I appreciate about Sunlighten saunas is their ability to offer a deep, detoxifying heat while being flexible enough to fit into smaller spaces and adapt to a variety of personal wellness needs.

► Hot Baths (and Jacuzzis)

Back in the 1980s, there was a famous commercial that showed a woman feeling overwhelmed, thanks to maddening traffic, an overbearing boss, her crying baby, and a barking dog. So, finally, she gets fed up and says, “That does it! Calgon, take me away!” (Calgon was, and apparently still is, a fragrant bathpowder.)

In the next scene, she’s enjoying a serene bubble bath in a luxurious mansion overlooking the beautiful countryside.

You get the point: Everyone knows a nice, hot bath (or hot tub) is relaxing. But as you’ve learned, it offers more than just an indulgent getaway from a hectic life.

Research shows regular hot baths are linked to lower blood pressure and decreased risk of a cardiac event, and they also help you fall asleep faster.

You don’t need to overthink it, but if you’re looking to elevate your experience and get the most out of your soak, I have a go-to bath protocol for you.

Check it out below, and the next time you need a break, just toss all the ingredients into the tub and say, “Dr. Hyman, take me away!” (Okay, don’t say that because if anyone hears you they may take away your car keys.)

Dr. Hyman’s Bath Protocol

Fill your tub with bathwater as hot as you can tolerate.

Then add the following:

1-2 cups of Epsom salts (magnesium sulfate)
½-1 cup of baking soda (sodium bicarbonate)
10 drops of lavender oil

The magnesium from the Epsom salts—which is absorbed through your skin— is great for reducing soreness and promoting muscle recovery. Plus, you’ll get the alkaline-balancing effects of the baking soda, and the cortisol-lowering effects of lavender, both of which help with sleep.

Ideally, take your bath just before bed every night. But if that’s not doable, work it into your life any chance you get.

Is Your Heat Therapy Working? Here’s How to Tell

One of the most obvious and immediate signs that heat therapy is working is sweating. When your body heats up, it naturally kicks into sweat mode to cool down—an early indication that the therapy is doing its job. But there’s more to it than just breaking a sweat. You’ll likely notice other short-term benefits, like muscle relaxation and pain relief, especially in areas where you’ve felt tension or discomfort.

Over time, you may also start experiencing longer-lasting effects, such as improved sleep quality and reduced stress. If you want to take a more scientific approach and track how heat therapy is working for you, keeping a journal can be a great way to measure your progress.

Track Your Progress

To determine if heat therapy is making a difference, it can be helpful to track your symptoms and overall well-being over time. Here are some factors you can monitor:

Pain levels before and after each session
Sleep quality and how rested you feel
Mental clarity and mood changes
Flexibility and ease of movement
Cardiovascular markers like blood pressure

By tracking these aspects for a few weeks or months, you’ll have a clearer picture of the long-term benefits of heat therapy.

References

Laukkanen JA, Kunutsor SK. The multifaceted benefits of passive heat therapies for extending the healthspan: A comprehensive review with a focus on Finnish sauna. Temperature (Austin). 2024 Feb 25;11(1):27-51. doi: 10.1080/23328940.2023.2300623. PMID: 38577299; PMCID: PMC10989710.
HASAN J, NIEMI M. Metabolic responses of human subjects to severe acute thermal stress. Acta Physiol Scand. 1954 Jul 18;31(2-3):140-6. doi: 10.1111/j.1748-1716.1954.tb01123.x. PMID: 13197082.
Brunt VE, Howard MJ, Francisco MA, Ely BR, Minson CT. Passive heat therapy improves endothelial function, arterial stiffness and blood pressure in sedentary humans. J Physiol. 2016 Sep 15;594(18):5329-42. doi: 10.1113/JP272453. Epub 2016 Jun 30. PMID: 27270841; PMCID: PMC5023696.
Laukkanen JA, Kunutsor SK. The multifaceted benefits of passive heat therapies for extending the healthspan: A comprehensive review with a focus on Finnish sauna. Temperature (Austin). 2024 Feb 25;11(1):27-51. doi: 10.1080/23328940.2023.2300623. PMID: 38577299; PMCID: PMC10989710.
Sears ME, Kerr KJ, Bray RI. Arsenic, cadmium, lead, and mercury in sweat: a systematic review. J Environ Public Health. 2012;2012:184745. doi: 10.1155/2012/184745. Epub 2012 Feb 22. PMID: 22505948; PMCID: PMC3312275.
Kunutsor SK, Jae SY, Kurl S, Kauhanen J, Laukkanen JA. Inflammation, sauna bathing, and all-cause mortality in middle-aged and older Finnish men: a cohort study. Eur J Epidemiol. 2022 Dec;37(12):1225-1231. doi: 10.1007/s10654-022-00926-w. Epub 2022 Oct 18. PMID: 36255556; PMCID: PMC9792415.
Pallubinsky H, Phielix E, Dautzenberg B, Schaart G, Connell NJ, de Wit-Verheggen V, Havekes B, van Baak MA, Schrauwen P, van Marken Lichtenbelt WD. Passive exposure to heat improves glucose metabolism in overweight humans. Acta Physiol (Oxf). 2020 Aug;229(4):e13488. doi: 10.1111/apha.13488. Epub 2020 Jun 1. PMID: 32359193; PMCID: PMC7379279.
Chang M, Ibaraki T, Naruse Y, Imamura Y. A study on neural changes induced by sauna bathing: Neural basis of the "totonou" state. PLoS One. 2023 Nov 27;18(11):e0294137. doi: 10.1371/journal.pone.0294137. PMID: 38011189; PMCID: PMC10681252.
Ogawa T, Hoekstra SP, Kamijo YI, Goosey-Tolfrey VL, Walsh JJ, Tajima F F, Leicht CA. Serum and plasma brain-derived neurotrophic factor concentration are elevated by systemic but not local passive heating. PLoS One. 2021 Dec 9;16(12):e0260775. doi: 10.1371/journal.pone.0260775. PMID: 34882699; PMCID: PMC8659342.