Sauna vs Hot Tub – Which One is Healthier?

Sauna use has been getting a lot of exposure for its health benefits, but a new study suggests that hot tubs might perform better in certain ways. In a previous article, we outlined the work of Dr. Ashley Mason and UCSF’s Sleep, Eating, and Affect (SEA) Lab, which has shown that whole-body hyperthermia (fever level core body temperatures) can significantly reduce depressive symptoms and boost mood. Beyond mood, these rises in body temperature can improve cardiovascular health, immune function, metabolism, and longevity.

Whole-body hyperthermia is best achieved with exercise, though researchers frequently use sauna. Likely because it can be accessible to individuals for whom exercise is not, but also because it can be an enjoyable supplement to an existing exercise routine.

Despite the attention given to saunas, a brand-new study out of the University of Oregon compared traditional sauna, infrared sauna, and hot water immersion, with hot water immersion producing the greatest rise in core body temperature. As expected, this was accompanied with hot water immersion causing the greatest thermoregulatory, cardiovascular, and immune responses.

While this suggests hot tubs might be more health-promoting than saunas, it is important that we look at the broader picture.

Saunas promote detoxification

While much of the sauna’s benefit comes from physiological adaptations to rising core body temperature, the detoxification through sweating cannot be ignored.

The high temperature and low humidity environment of the sauna promotes intense sweating. Sweat is one of the main routes the body uses to clear toxins, and by increasing sweat production, the sauna can enhance natural detoxification. Clinical studies have shown that sauna-induced sweating can eliminate things like heavy metals (cadmium, lead, and aluminum), as well as endocrine-disrupting phthalates, flame retardants, bisphenol A (BPA), pesticides, and PCBs.

In contrast, despite raising core body temperature effectively, hot tubs do not produce the same sweat response. Being surrounded by water, our sweat doesn’t evaporate as it does in a sauna, leading to less being released.

While we do sweat in hot tubs, we sweat significantly more in the sauna. Despite hot tubs being more effective at raising core body temperature, there may still be a role for saunas in our routine.

Hot Tub Chemicals

One of the greatest concerns with frequent hot tub use is chronic chemical exposure.

Most hot tubs rely on chlorine or bromine to sanitize the water and prevent growth of harmful bacteria. Our skin is highly absorbent, rapidly taking up almost anything it is exposed to, and the heat of the water can actually enhance absorption of these chemicals.

Anyone who filters their tap water to remove chlorine and other chemicals should be similarly mindful of the water being exposed to their skin.

Chemical vapors from hot tub chemicals can also cause respiratory problems, especially in enclosed spaces with poor ventilation. Short-term exposure can lead to airway inflammation and asthma symptoms, while chronic exposure has been linked to increased risk of respiratory problems such as bronchitis and structural changes similar to chronic obstructive pulmonary disease (COPD).

Some studies even suggest potential links between prolonged exposure to pool and spa chemicals and increased rates of certain cancers, including bladder cancer. It’s important to note that research here is limited, and the few links that do exist primarily involve chronic high exposure and also account for disinfection chemicals in drinking water. However, it is still important to be mindful of the chemicals we repeatedly bathe in.

How to Hot Tub Safely

Since the research points towards hot tubs being effective in raising core body temperature and providing accompanying health benefits, we can explore ways to mitigate the chemical exposure.

There are now advanced sanitization systems that use ozone or UV light to kill bacteria and can reduce the chlorine or bromine requirements by 50-80%. There are also mineral or enzyme-based treatments which can also reduce the bacterial load, requiring less chemical treatment. Ensuring the water sits at the correct pH (7.2-7.8), is continually filtered, and is changed every 3-4 months, further reduces the chemical requirements.

In addition to exploring non-chemical strategies for bacteria mitigation, it is recommended to always rinse off before getting in the hot tub. This reduces the amount of bacteria you bring into the tub, allowing you to keep the water hygienic with fewer chemicals.

Rinsing off after the tub is also recommended as it washes any chlorine or bromine off your skin, preventing you from going the rest of the day exposed to these chemicals.

Sauna or Hot Tub?

The main takeaway here is that these two heat-based tools can both be beneficial. Sauna excels in detoxification through sweat, though you still get plenty of detoxification in the hot tub. The hot tub excels in raising your core body temperature and producing the associated cardiovascular and mood benefits, though the sauna also does this well.

If you’re lucky enough to have access to both tools, alternating between them likely provides the most holistic benefits. If you are deciding between them, consider what benefits are most important to you. Also consider which one you will realistically enjoy more, as this will make you more likely to actually use it. If you decide on the hot tub, be mindful of the chemical exposure and employ the strategies listed above to reduce chemical requirements.

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