The belief that heat can benefit the mind and relieve psychic suffering has a long history across human societies. But when Eva Hilland scanned the scientific literature for the kind of evidence that would support recommending heat as a legitimate intervention for mental health, she came up with very little. "There are many knowledge gaps," says Hilland, a cognitive neuroscientist at Oslo Metropolitan University.
Although, what existing evidence she did find seemed promising. "So we just saw the potential." Sauna-going – sometimes paired with cold plunges or winter swimming – is attracting a new generation of followers, from the U.S. to Hilland's sauna-steeped country of Norway. The trend not only reflects the reach of the broader wellness and longevity movement, but also a thirst for communal experience and social connection, particularly in the wake of the pandemic.
The science is just beginning to catch up with many of the theorized benefits. Though considerably less studied than the cardiovascular impact, mental health has emerged as one of the more exciting and appealing applications. Hilland, whose research group focuses on neuroimaging and genetics, is one of the scientists now diving into this research domain of heat and mental health.
And she's leveraging the sauna popularity surge in her own city, Oslo, to do it. With funding from a local municipality, she's recruiting 50 people for a randomized controlled trial to see whether coupling sauna with a simple set of mental health habits improves stress, well-being, sleep and more. Instead of visiting a windowless research lab, her study participants take two sessions a week at one of the floating sauna villages that have cropped up in Oslo's inner harbor – a waterfront that has transformed into a world-class destination for heat-seekers in just the past decade.
Large surveys of sauna users reflect what many readily share: It's the psychological benefits more than anything else that keeps them coming back, whether that's stress reduction, elevated mood, improved sleep or the ineffable post-sauna glow. Some of these self-reported improvements may have less to do with sweating and more to do with the digital detox, time in nature, mindfulness and social connection that sauna-going facilitates. But the weight of the evidence suggests heat itself is also "powerful physiological stimulus for promoting mental health," says Christopher Lowry, an integrative physiologist and neuroscientist at the University of Colorado, Boulder.
While warm baths were commonplace in psychiatric asylums a century ago, the modern evidence base largely rests on translational work done with animals and cell models, and a small number of human studies, most of which lack strict control groups. In his lab, Lowry has extensively explored the physiological mechanisms linking temperature and mental health. When our skin senses heat, those signals travel to a primitive part of the brain that tells our body to cool down.
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