EDA

Estimated stress based on HRV and other metrics

Sweat response indicates stress

Electrodermal activity (EDA), also known as galvanic skin response (GSR) or skin conductance, measures electrical conductance changes in the skin caused by sweat gland activity. The sympathetic nervous system controls eccrine sweat glands, making EDA a direct window into autonomic arousal states. Skin conductance is measured in microsiemens (μS), with tonic levels (baseline) typically 1-20 μS and phasic responses (event-related) showing rapid increases during stress, emotional arousal, or cognitive load. Wearables detect EDA through electrodes contacting the skin, commonly on the wrist or fingers where eccrine gland density is high. EDA is used for stress detection, emotional state monitoring, sleep quality assessment, and biofeedback applications. Accuracy can be affected by electrode contact quality, skin moisture, ambient temperature, and movement artifacts.

Direct measurement