Effects of sleep loss on medical residents' emotional reactions to work events: a cognitive-energy model

STUDY OBJECTIVES: This study investigated the relationship between sleep loss and emotional reactivity in medical residents. We hypothesized that this relationship is shaped by the effect of sleep loss on cog-nitive-energy resources required for coping with goal-disruptive events or for capitalizing on new opportunities offered by goal-enhancing events. SETTINGS: 15 medical wards in 4 large hospitals in Israel. PARTICIPANTS: 78 medical residents, 67% men, aged 26 to 39 years. DESIGN: Actigraphic sleep-wake cycles were measured for 5- to 7-day periods, surrounding nightshifts, every 6 months, covering the first 2 years of residency. During each study period, emotional reactivity was investigated using the experience-sampling methodology by which residents received 3 phone calls at random times during their working day for 3 consecutive days. These calls reminded them to fill out brief questionnaires concerning change of circumstances over the previous 15 minutes and to rate their emotional response to these circumstances using the Positive Affect and Negative Affect Scales. Fatigue at those times was measured by a subscale of the Profile of Mood States. MEASUREMENTS AND RESULTS: Multilevel regression analysis was used to determine the influence of sleep duration and sleep fragmentation on the emotional reactions to goal-disruptive and goal-enhancing daytime events. We found that sleep loss intensified negative emotions and fatigue following daytime disruptive events, while positive emotion was mitigated following goal-enhancing events. Sleep loss also resulted in an overall elevated baseline for positive emotion. CONCLUSIONS: Sleep loss amplifies the negative emotive effects of disruptive events while reducing the positive effect of goal-enhancing events. Methodologically, the study highlights the utility and advantages of event-level analysis as opposed to the current practice of random sampling of emotion states during waking hours, disregarding contextual factors associated with purposeful, goal-oriented behavior episodes