Lighting scheme recommendation for interior workplace to adjust the phase-advance jet lag

Abstract

Light has been found to affect the circadian clock of the human body. This study aims at exploring the proper light scheme for improving performance and alleviating the negative effects of phase-advance jet lag. Herein, the light intervention intensity during an 8-h working time after a simulated eastward flight is set as a variable. 27 healthy young adults participate in a 7-day circadian phase control and 4-day closed circadian conversion experiment. Participants are assigned to three groups according to lighting conditions: (1) control lighting group (CLG), (2) low-intervention group (LIG), and (3) high-intervention group (HIG). The alertness, sleep quality, and circadian phases of the participants are measured during the closed circadian conversion stage. Statistical analysis results show that, compared to CLG, HIG can effectively reduce the effect of the phase-advance jet lag syndrome on alertness during daytime (p = .028), improve short-term memory task performance (p < .001), and reduce visual fatigue (p = .016); besides, the 8-h light intervention during daytime assists in improving sleep quality. The results for dim light melatonin onset (DLMO) evidence that the HIG scheme can advance the circadian phase by 7.17 ± 0.71 h and is thus recommended for adjusting phase-advance jet lag in interior public workplaces. Finally, a model between light stimulus intensity and the circadian phase shift is deduced with a high correlation R2 > 0.99.