Warmer skin temperature linked to manic episodes

Wrist sensors track temperature before and after remission

Wearable data link warmer skin to manic episodes in bipolar disorder

People with bipolar disorder had higher body temperatures during manic episodes than at other times, according to a new study. It tracked skin temperature with wrist-worn sensors and compared readings before and after symptoms eased.

It shows skin temperature could become a simple “digital vital sign” for monitoring mania. The research was led by researchers at Hospital Clínic de Barcelona and collaborators in the U.K. and Australia.

The study had 104 adults with bipolar disorder who were experiencing depression, mania, or were stable, a state called euthymia. There were also 35 healthy controls.

Participants in manic or depressive episodes wore an Empatica E4 wearable for 48 hours during the acute phase and again after remission; those who were euthymic and healthy controls were monitored once.

The authors used statistical models to rule out other variable, including season, movement, age, sex, and medications.

What they found
From 9 a.m. to 11 p.m., average skin temperature reached 92.5F in the manic group versus 91F in those who were euthymic — a difference of 1.5F that was statistically significant.

After symptoms improved, the manic group’s mean dropped to 91.8F, narrowing the gap. By contrast, depressed participants showed no meaningful temperature differences during the episode or after remission.

Why it matters
Mania can escalate quickly, disrupting sleep, judgment, and safety. Clinicians typically use self-reports or infrequent assessments to spot changes.

A passive marker like skin temperature — captured by common wearables — could fit in with other digital tools that already track sleep and activity to warn of mood shifts.

Recent work shows circadian disruptions are common in bipolar disorder, and wearables can help quantify those rhythms in daily life, making temperature a promising addition.

What’s next
The researchers say the results support including skin temperature into monitoring for bipolar disorder. Future trials could test whether temperature-informed alerts, combined with sleep and activity data, help patients and care teams intervene earlier to prevent hospitalization or relapse.

Sources: Journal of Affective Disorders, June 9, 2025, https://pubmed.ncbi.nlm.nih.gov/40499838/

Note from a person living with bipolar I: While experiencing a lengthy manic episode, I noticed my body temperature feeling a bit hotter. I attributed this to moving around so much. While I did not take my temperature with a thermometer, or have a wearable tracking device, feeling warmer is my anecdotal experience. If I hadn’t lost my Oura Ring during the peak of mania, I might have had more metrics to review.

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