Depression and a rise in body temperature appear linked, although researchers say it's not yet clear which causes which.

Still, the findings offer a hint that manipulating body temperature might be a new form of therapy against depression.

“To our knowledge, this is the largest study to date to examine the association between body temperature — assessed using both self-report methods and wearable sensors — and depressive symptoms in a geographically broad sample,” said study lead Ashley Mason, an associate professor of psychiatry at the University of California, San Francisco (UCSF).

“Given the climbing rates of depression in the United States, we’re excited by the possibilities of a new avenue for treatment," she added in a UCSF news release.

The new study involved more than 20,000 people from 106 countries who wore a device that measured their body temperature. The study ran for seven months, beginning in early 2020.

As a person's level of depression severity rose, so, too, did their body temperatures, Mason's group reported.

The findings were published Feb. 5 in the journal Scientific Reports.

There was also a trend suggesting that folks whose body temperatures remained stable over a 24-hour period also had higher risks for depression — but the finding didn't quite meet statistical significance, the investigators said.

It's also unclear whether higher body temperature can help trigger depression, whether depression impairs the body's ability to regulate its temperature — or whether the depression/temperature link involves a little of both.

Mason says more study is planned. “What if we can track the body temperature of people with depression to time heat-based treatments well?” she said.