Scientists Explore Heat Therapy as a Treatment for Depression and Mental Health

A growing movement of wellness enthusiasts in the United States and Norway is turning to saunas, often combined with cold plunges or winter swimming, seeking relief from mental health struggles. While the practice has deep historical roots across various cultures, the scientific community is only beginning to validate these anecdotal benefits through rigorous clinical trials.

Eva Hilland, a cognitive neuroscientist at Oslo Metropolitan University, notes a significant gap in the literature when it looked for evidence to support heat as a legitimate mental health intervention. Despite these gaps, she found the existing data promising enough to pursue further study. Leveraging the surge in sauna popularity in Oslo, Hilland is leading a randomized controlled trial recruiting 50 participants. Funded by the local municipality, the study examines whether combining regular sauna sessions with established mental health habits improves stress levels, well-being, and sleep.

Unlike traditional laboratory settings, this research takes place at floating sauna villages in Oslo’s inner harbor, a waterfront area that has evolved into a major destination for heat therapy enthusiasts over the last decade. Participants attend two sessions per week at these floating facilities.

Christopher Lowry, an integrative physiologist and neuroscientist at the University of Colorado Boulder, describes heat as a “powerful physiological stimulus” for mental health. He explains that when skin senses heat, signals travel to a primitive part of the brain to initiate cooling. This pathway overlaps with systems involved in mood and pleasure, which are often impaired in depression. Additionally, heat triggers an anti-inflammatory response similar to that seen during exercise, a well-known treatment for depression. Animal studies conducted in Lowry’s lab also suggest that heat activates serotonin neurons, potentially providing stress resilience and antidepressant effects.

One of the most compelling pieces of human evidence comes from a landmark trial published ten years ago, led by researchers at the University of Wisconsin-Madison and co-authored by Lowry. The study involved 30 individuals with depression who were divided into two groups. One group spent approximately two hours in a whole-body infrared device designed to raise body temperature to 38.5 degrees Celsius (101 degrees Fahrenheit), while the other received a sham treatment. Within a week, the majority of the treatment group experienced a 50% reduction in symptoms, and these improvements persisted through a six-week follow-up period.

These findings inspired Ashley Mason, a clinical psychologist at the University of California, San Francisco, to explore heat therapy for mood disorders, sleep issues, and loneliness. Supported by funding from the National Institutes of Health and other sources, Mason’s research focuses on the connection between depression and thermoregulation.

“Depressed people seem to run hot,” Mason said. Her lab recently analyzed wearable device data from nearly 20,000 people, finding a correlation between higher self-reported depression symptoms and elevated skin temperature with less daily fluctuation. Specifically, individuals with more severe symptoms showed less cooling of the body at night.

Mason likens heat exposure to a “thermoregulatory workout.” By exposing the body to heat, the system may become more efficient at cooling down later, resulting in a prolonged drop in body temperature that can last for days or weeks. This approach counters the counterintuitive idea of heating already “hot” depressed individuals to help regulate their body temperature.

Older studies have also indicated that successful treatment with antidepressants or other therapies can improve thermoregulation. Mason suggests a bidirectional relationship where both heat therapy and traditional treatments could have synergistic effects. She has conducted several small pilot trials combining heat therapy with cognitive behavioral techniques to test this hypothesis, marking the beginning of a new era in understanding the mental health benefits of heat.