LAUSR

Delayed eating rhythms, relative to the sleep/wake period, commonly manifest as a lack of hunger in the morning (morning anorexia) and elevated hunger in the late evening (evening hyperphagia). These intake patterns are associated with adverse mental and physical health outcomes. We aimed to evaluate whether the timing of light exposure, an important environmental signal for circadian synchronization, explains the link between sleep/waketime preferences and delayed diurnal appetite. We also aimed to test whether disruptions in sleep quality, reflecting suboptimal circadian synchronization, identify individuals for whom sleep/waketime preference is associated with delayed diurnal appetite. Participants (N = 150) completed a measure of their sleep/waketime preferences and wore a device to capture their sleep efficiency and naturalistic light exposure for 48 consecutive hours. The timing of light exposure mediated the link between sleep/waketime preferences and evening hyperphagia, but not morning anorexia, such that a later peak in light exposure mitigated some of the risk for evening hyperphagia that was associated with later sleep/waketime preferences. Sleep efficiency moderated the association between sleep/waketime preference and morning anorexia, but not evening hyperphagia. Earlier sleep/waketime preference was associated with less morning anorexia among individuals with high sleep efficiency, but morning anorexia was consistently elevated among individuals with poor sleep efficiency. These results on the relation between sleep/waketime preference and two aspects of delayed diurnal appetite suggest that morning anorexia depends on sleep efficiency and evening hyperphagia may be influenced by the timing of daily light exposure. Future research should assess over longer periods, covering weekdays and weekends, and incorporate momentary reports of meals/snacks and appetite.