Depressed People Are Hotter. Scientists Want to Try Cooling Them Down

Our body temperature may be inextricably tied to our mental health, research out this week suggests. A team of scientists has found evidence that higher body temp is associated with having clinical depression. While there are many unresolved questions about this link, the researchers have already begun to conduct human trials to confirm and further understand the phenomenon.

The research was led by scientists from the University of California San Francisco. Some studies in the past have indicated a possible link between body temperature and depression, but these generally have only included small numbers of people. As it turns out, these study authors had a much larger dataset on their hands that could help them investigate the topic: the TemPredict study.

The TemPredict project was originally intended to figure out whether wearable sensors that detect changes in skin temperature and other physiological factors could be used to predict a covid-19 infection earlier than usual (long story short: probably!). But the study’s design also meant that you could look at the temperature readings and general health of a large group of people at once, including their self-reported symptoms of depression.

For this new research, published Monday in Scientific Reports, the team looked at data from more than 20,000 participants enrolled in the TemPredict study. They found a noticeable association between having depression symptoms and an overall higher body temperature, both in terms of self-reported temperature readings and data from wearables. And the higher their temperature, the more severe a person’s depression tended to be, further strengthening the case for a clear link.

“Though there are studies from decades ago documenting a correlation between depression and body temperature, those studies were small, often with 10-20 people in them,” lead study author Ashley Mason, an associate professor of psychiatry at UCSF Weill Institute for Neurosciences, told Gizmodo in an email. “This study that we have just published shows this correlation in a much larger sample, and will hopefully inspire more work into the mechanisms that underpin this correlation.”

This kind of study can only demonstrate a correlation between temperature and mental health, not directly prove a cause-and-effect link. And it’s still unclear exactly how this relationship might work, if it genuinely does exist. It’s not known whether having depression raises our body temperature, for instance, or if higher body temperature raises our risk of feeling depressed—or maybe it can be both, depending on the situation.

“The link is particularly fascinating because there are data showing that when people recover from their depression—regardless of how they got better—their temperature tends to regularize. Then we have newer data suggesting that temperature-based interventions may reduce depression symptoms,” Mason said. “For example, data have shown that using heat-based treatments, in particular infrared sauna, causes acute increases in body temperature. These increases in body temperature engage the body’s self-cooling mechanisms (think, sweating) and can lead to subsequent decreases in body temperature (we sweat, we cool ourselves down).”

Mason and her team are already beginning to explore the practical implications of their research. They’ve wrapped up their first sauna-related study, with peer-reviewed data set to come out later this year, and they’re currently recruiting volunteers for their second HEAT Bed study, which will test whether the addition of sauna sessions to cognitive behavioral therapy can improve outcomes for people with clinical depression. It’s possible that someday, sauna or other temperature-related treatments alone could be regularly used to keep depression at bay, Mason noted.

“These data are exciting because they might suggest a body-based treatment for depression that doesn’t involve medications or traditional psychotherapy,” she said.