The researchers wanted to know whether sensitive equipment could capture some of these changes and connect them with reported mental health symptoms. Caffeine, medications, lack of sleep, illness, room temperature and a person’s general heart health can also affect measurements taken from the skin. Mental health professionals currently rely heavily on conversations, a person’s history, observed symptoms and carefully designed questionnaires because emotional experiences cannot be reduced to a simple sensor reading. Participants were not classified according to diagnoses made by mental health professionals; instead, researchers used the answers they gave on a symptom questionnaire. It suggests that fingertip measurements could someday add useful information to mental health monitoring, but human judgment, clinical assessment and a person’s own description of their experiences remain central to understanding mental health.