Fig. 1: Trial protocol and profile.

a Trial protocol. Patients were randomly allocated to either bright light exposure group (BL group) or dim light exposure group (DL group), utilizing the envelope method in a 1:1 ratio. Both BL group and DL group had an actigraphy system to measure illuminance. BL group received bright light (10,000 lux) derived from the light therapy device and DL group received dim light derived from the light therapy device fixed with 50 lux. Light exposure had done for 30 min between 7:00 a.m. and 7:30 a.m. every morning for 4 weeks. b Trial profile. Twenty-eight patients were assessed for eligibility, and four declined to participate in the study. The remaining 24 patients were diagnosed with mood disorder and randomized to either the BL or DL group, with 12 patients in each group. All patients completed the protocol, resulting in a final sample size of 24.