Circadian Misalignment and Sleep Disruption in Shift Work: Implications for Fatigue and Risk of Weight Gain and Obesity

Abstract

The interplay of circadian timing and metabolic physiology represents a new frontier in biomedical research. Emerging evidence from animal models indicates that circadian physiology impacts weight gain, including the observation of obesity in clock gene mutants and most recently the finding that food intake restricted to the habitual sleep time of mice leads to weight gain as compared to the same amount of food intake during the normal wake episode. Eating at night is common in work schedules with long work hours and with work operations during the nighttime hours (e.g., health care, emergency response, security personnel) and in circadian sleep disorders including, but not limited to, shift work disorder. Shift work and shift work disorder are associated with circadian misalignment, sleep disruption, and fatigue, all of which may contribute to weight gain and obesity via the modification of feeding hormones and perhaps total daily energy expenditure. Future research is needed to explore the impact of circadian misalignment/sleep disruption and the resulting fatigue on metabolic physiology in shift workers, the mechanisms underlying this association and to develop effective countermeasures to promote shift worker health and well-being.