Circadian misalignment increases mood vulnerability in simulated shift work

• Published in: Scientific reports Vol. 10; no. 1; p. 18614
• Main Authors: Chellappa, Sarah L., Morris, Christopher J., Scheer, Frank A. J. L.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 29.10.2020; Nature Publishing Group
• Subjects: 631/378; 631/378/1385; Adult; Affect - physiology; Circadian Rhythm - physiology; Circadian rhythms; Environmental conditions; Female; Food intake; Humanities and Social Sciences; Humans; Male; Middle Aged; Mood; multidisciplinary; Nighttime; Occupational exposure; Pacemakers; Science; Science (multidisciplinary); Shift work; Shift Work Schedule - adverse effects; Sleep; Sleep - physiology; Sleep and wakefulness; Sleep deprivation; Sleep Disorders, Circadian Rhythm - physiopathology; Well being; Work Schedule Tolerance - physiology; Young Adult
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-020-75245-9

Night shift work can associate with an increased risk for depression. As night workers experience a ‘misalignment’ between their circadian system and daily sleep–wake behaviors, with negative health consequences, we investigated whether exposure to circadian misalignment underpins mood vulnerability in simulated shift work. We performed randomized within-subject crossover laboratory studies in non-shift workers and shift workers. Simulated night shifts were used to induce a misalignment between the endogenous circadian pacemaker and sleep/wake cycles (circadian misalignment), while environmental conditions and food intake were controlled. Circadian misalignment adversely impacted emotional state, such that mood and well-being levels were significantly decreased throughout 4 days of continuous exposure to circadian misalignment in non-shift workers, as compared to when they were under circadian alignment (interaction of “circadian alignment condition” vs. “day”, mood: p  < 0.001; well-being: p  < 0.001; adjusted p -values). Similarly, in shift workers, mood and well-being levels were significantly reduced throughout days of misalignment, as compared to circadian alignment (interaction of “circadian alignment condition” vs. “day”, mood: p  = 0.002; well-being: p  = 0.002; adjusted p -values). Our findings indicate that circadian misalignment is an important biological component for mood vulnerability, and that individuals who engage in shift work are susceptible to its deleterious mood effects.