Objectives This study aimed to characterize physical activity, sleep, heart rate, and circadian rhythm in each Sasang constitutional type using data collected from wearable devices.
Methods A total of 797 adults who participated in the Korean Medicine Daejeon Citizen Cohort and wore a wrist-worn wearable device (Fitbit Inspire 2) for at least seven consecutive days were included. Sasang constitutional types were determined using the KS-15 questionnaire. Stratified analyses were conducted by sex, and comparisons among Sasang constitutional groups were performed on variables related to physical activity, sleep, heart rate, and circadian rhythm.
Results Significant constitutional differences were more prominent in females than in males. In females, the number of steps and moderate-to-vigorous physical activity were lowest in the Soeumin. Taeeumin showed a tendency toward lower sleep efficiency and shorter light sleep duration, along with higher all-day, sleeping, inactive, and minimum heart rates, and a reduced heart rate dip. Regarding circadian rhythm, Taeeumin exhibited significantly lower relative amplitude, and delayed acrophase compared to both Soeumin and Soyangin with significantly later M10 start time and sleep onset time compared to Soyangin. In males, only inactive heart rate showed a borderline significant difference among constitutional types.
Conclusions This is the first study to objectively compare physiological and behavioral features among Sasang constitutional types using wearable devices. The findings partially align with traditional descriptions, while presenting novel patterns that may contribute to a broader understanding of constitutional characteristics.