You probably know the feeling after a long sit in a hot sauna.
The body loosens, the mind quiets, and something lifts for the rest of the day.
More researchers now think that feeling is worth testing seriously.
Several teams in the United States and Europe are running clinical trials on whether heating the body deeply can treat depression.
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The strongest early evidence comes from a 2016 randomized trial in JAMA Psychiatry, led by researchers at the University of Wisconsin-Madison.
Thirty adults with major depression were warmed in an infrared device until their core body temperature reached 38.5 degrees Celsius, about 101 degrees Fahrenheit.
The warming phase averaged just under two hours.
Within a week, the depression scores of the treated group had dropped sharply compared with a sham group.
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The effect was still clearly visible six weeks later, after that single session.
That trial was tiny, as early-stage studies often are. But it opened the door, and more careful work has followed.
What the newer trials have found so far
A newer trial led by Ashley Mason, a clinical psychologist at the University of California San Francisco, paired heat therapy with talk therapy.
The study, published in Global Advances in Integrative Medicine and Health in October 2025, enrolled 30 adults with major depression.
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All received eight weeks of cognitive behavioral therapy, a form of talk therapy.
Half also got four real heating sessions, and half got sham sessions.
Both groups improved sharply. Depression scores dropped by about 20 points on average, enough to put most people into remission by the end of the study.
That result is encouraging and also a warning sign.
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If the sham group did almost as well as the real heat group, the trial cannot yet prove the heat itself was doing the work.
Mason has told reporters the field is still at the beginning.
Larger follow-up trials are now running at UCSF, Harvard and the Cleveland Clinic.
A separate study in Oslo is approaching the question from another angle.
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Cognitive neuroscientist Eva Hilland at Oslo Metropolitan University is testing floating saunas combined with everyday mental health habits in 50 people, measuring stress, well-being and sleep.
How heat might actually lift mood
Researchers think the effect may run through the body's temperature-control system.
People with depression often have trouble shedding heat normally, and some run slightly warmer through the day.
A long, deep warm-up seems to force the cooling system into gear.
Think of it as a workout for the body's thermostat, not for the muscles.
Heat also activates serotonin pathways in the brain stem that are linked to stress resilience and mood.
And like exercise, intense heat triggers an anti-inflammatory response that researchers suspect plays a role.
None of this means an evening sauna is a treatment.
The trials used tightly controlled infrared devices, careful monitoring and a specific target temperature.
A home or gym sauna is not the same thing.
What this means for ordinary sauna use
The strongest evidence for everyday sauna use is still cardiovascular, not mental.
Finnish research has tied regular sauna sessions to better heart outcomes, and we have covered how regular sauna use may protect your heart about as well as moderate exercise.
People with depression, heart conditions, low blood pressure or who are pregnant should talk to a doctor before starting regular sauna use.
Heat is a strong stimulus, and anyone already on treatment for depression should not drop it based on early research.
The real test will come when the larger trials at UCSF, Harvard and the Cleveland Clinic report their results.
This article is made and published by Ida-Marie Palm Varbæk, who may have used AI in the preparation.