STUDY OBJECTIVES: Recent evidence indicates that daytime sleep disturbance associated with night shift work may arise from both circadian misalignment and sleep reactivity to stress. This presents an important clinical challenge because there are limited means of predicting and distinguishing between the two mechanisms, and the respective treatments differ categorically; however, there is support that a polymorphism in thegene () may indicate differences in vulnerability to daytime sleep disturbance in shift workers. PERIOD3PER3
METHODS: We recruited 30 fixed night shift workers for laboratory assessments of circadian misalignment (dim light melatonin onset), sleep reactivity to stress (Ford Insomnia Response to Stress Test), daytime sleep disturbance (daytime Insomnia Severity Index), andgenotype (). The two mechanisms for daytime sleep disturbance (circadian misalignment and sleep reactivity to stress) were compared betweengenotypes. PER3PER3, PER3 4/4PER3 /-5
RESULTS: Disturbed daytime sleep in thegroup was more likely related to sleep reactivity to stress, whereas disturbed sleep in thegroup was more likely related to circadian misalignment. Exploratory analyses also revealed a blunted melatonin amplitude in thegenotype group. PER3 4/4PER3PER3 4/4 /-5
CONCLUSIONS: This study provides further evidence for multiple mechanisms (ie, circadian misalignment versus sleep reactivity to stress) associated with daytime sleep disturbances in shift workers. Additionally, it provides the new finding thatgenotype may play an important role in individual vulnerability to the different mechanisms of daytime sleep disturbance in night shift workers. PER3
