Embracing sauna culture can lower dementia risk and boost brain health

I’m already a dedicated cold water swimmer and last year I wrote about its benefits for the brain. But I started reading more and more about heat therapy and It is neurological benefits. And even though the evidence is only just beginning to emerge, it’s starting to look pretty compelling, so I decided to investigate further.

For science, I made the most of Scandinavian sauna culture during my stay in Finland and Sweden last month. I also learned that “sauna” is pronounced “sow-na” (with the “ow” rhyming with “how”), rather than my south-east London pronunciation of “s”.Orn / A”.

Finnish saunas, which are typically heated between 70°C and 110°C (158°F and 230°F) and have low humidity, are the most studied. Regular consumption is associated with many physical benefits – a lower risk of hypertension, muscle problems and respiratory problems, for example. But researchers are now beginning to reveal cognitive benefits as well. These improvements include fewer headaches, increased mental well-being, better sleep and lower risk of dementia.

In one of the largest studies I’ve seen, nearly 14,000 people aged 30 to 69 were asked about their sauna use as part of a larger health study, and followed up 39 years later. After adjusting for other lifestyle factors, people who visited the sauna more frequently – going to the sauna nine to 12 times per month versus fewer than four times per month – had a 19% reduced risk of dementia at the end of the study.

We have seen that beyond dementia, sauna is also associated with several other cognitive benefits. In a small trial, 37 adults with chronic headaches received advice on headache management or attended saunas regularly and received the same advice for eight weeks. Members of the sauna plus education group showed significant improvement in headache intensity. Regular saunas have also been linked to a reduced risk of psychosis, as well as an increase in vitality, your ability to live in a way you personally enjoy, and social functioning in older adults.

However, not all heat therapies are the same. While traditional saunas are the most common, other types of thermal therapy exist, with their own benefits. For example, in one small trial, 26 people with major depressive disorder received either a single whole-body infrared warming session or a sham treatment. Unlike traditional saunas which use hot air to warm the body, infrared heating uses electromagnetic waves. The sham treatment looks and sounds the same, but the waves are not activated. Those who received the real treatment reported fewer symptoms over six weeks and showed changes in interleukin-6 signaling, a pathway involved in inflammation, strongly linked to depression.

Why does heat therapy help the brain?

The anti-inflammatory effects of heat therapy appear to be the key to its many benefits. In 2018, Setor Kunutsor, then at the University of Bristol, UK, and colleagues analyzed sauna habits and blood markers of inflammation in 2,269 middle-aged Finnish men, following them for 11 years. After controlling for factors such as alcohol consumption and physical activity, the researchers found that frequent sauna sessions were associated with lower levels of several different inflammatory markers. The team concluded that sauna health benefits may come in part from a reduction in inflammation, since chronic inflammation is strongly linked to depression, cognitive decline and other neurological disorders.

Another possible mechanism is thermal shock. When your body temperature rises, due to exercise or passive heating, it triggers the production of heat shock proteins – molecules that act as chaperones for other proteins, ensuring they don’t misfold or go astray. These elements are essential because misfolded proteins are the hallmark of many neurological conditions. Last year, scientists discovered more than 200 types of misfolded proteins in the brains of rats associated with dementia and age-related decline, beyond the familiar amyloid and tau of Alzheimer’s disease. This suggests that the protective effect of heat shock proteins could be a key part of the story.

Better blood circulation may also play a role. Heat causes blood vessels to dilate, improving cardiovascular function, blood pressure and arterial stiffness. Since decreased blood flow contributes to vascular dementia and Alzheimer’s disease, maintaining good cardiovascular health may indirectly benefit the brain.

Saunas may also increase the amount of brain-derived neurotrophic factor (BDNF) circulating in the blood. These molecules act like fertilizer, helping neurons grow, and low levels are associated with depression and anxiety. In one trial, 34 men received either 12 or 24 sessions of infrared heating, over 10 weeks, or a low-intensity exercise program. Those who experienced repeated hyperthermia showed significantly higher BDNF levels and reported better quality of life and lower anxiety than those assigned to gentle exercises.

Can saunas help you think better?

The potential long-term neurological benefits weren’t all that interested me. A small study of 16 men whose brain activity was recorded by EEG before and after a sauna suggests that it’s not only a short-term relaxing practice, but might also help us think more effectively. The participants’ brainwave activity more closely resembled a relaxed state after the sauna, and although they did not do better on two tasks given to them shortly after leaving the sauna, their brain activity showed signs of greater efficiency in the tasks, suggesting less effort for the same results. Researchers see heat therapy as a potential way to increase our ability to “maintain our mental working capacity for a longer duration.”

Of course, it’s not all good news. Most of us are familiar with the sluggish, foggy feeling that comes with spending too much time in the sun, and studies of people exposed to 50°C (122°F) heat for an hour confirm this: Exposure to this high level of heat changed the way brain regions communicated with each other, which was directly linked to slower reaction times. There is also some evidence that exposure to heat can harm memory consolidation, so perhaps avoid saunas if you’re preparing for an exam.

If you’re new to heat therapy, the British Sauna Society provides safety guidelines, including limiting your time in a sauna to acclimatize to the heat, moving slowly and hydrating regularly, as well as other tips to keep you safe.

Can a hot bath have the same effect?

What if you don’t live in a sauna-loving society or a hip neighborhood with pop-up sweat boxes? Can a hot bath do the trick instead? Unfortunately, the jury is out. Hot baths can only partially replicate the benefits of saunas, says Ali Cadili of West Virginia University Medicine. They increase your core temperature, and repeated hot baths – 30 minutes, five days a week for four weeks – have been shown to decrease resting heart rate and promote a feeling of relaxation, which can improve mood. However, he says there is no direct comparison between saunas and hot baths. Cadili considers baths a viable alternative to saunas if they are all that is available, but cautions that we need to keep in mind that there is a greater amount of robust, long-term data on the association of saunas with dementia and stroke prevention.

With cold water swimming and heat therapy offered at my nearby lake, I wondered if combining the two might amplify the effects of each. Research is scarce, but I came across a study on what in Japan is called totonou condition – the intense feelings of happiness that people report after alternating a hot sauna with cold water.

In the study, participants alternated three times between a hot sauna, exposure to cold water, and rest. The researchers measured brain activity before and after the three cycles and found an increase in brain wave patterns associated with relaxation and a reduction in demand for attention.

It’s not yet clear whether this is a better brain condition than that achieved by cold or heat therapy alone, but overall it’s much more than I thought I’d get from sitting in a hot wooden box. So no, I don’t need another excuse to go to the lake or spa, but it’s reassuring to know that in addition to the immediate pleasure I get from such visits, more regular saunas might also provide a cognitive boost to my brain, now and in the long term.