Peripheral skin temperature differentiates unipolar and bipolar depression

We read with interest the recent study by Valenzuela-Pascual et al. reporting an increase in peripheral skin temperature during manic episodes compared to depressive episodes in patients with bipolar disorder (Valenzuela-Pascual et al., 2025). Their results suggest that skin temperature, passively recorded by wearable sensors, could serve as a state-dependent physiological marker of manic versus depressive phases. This aligns with recent efforts to identify objective physiological correlates of psychiatric symptoms using unobtrusive, ecological tools. We would like to offer a complementary perspective based on data from the CALYPSO study, in which peripheral skin temperature was used to explore trait-level physiological differences between unipolar and bipolar depression.

Published as a journal paper in Journal of Affective Disorders.