The Role of Sleep and Hormones in Processing of Emotional Information
The current study aimed to investigate emotion processing after a single night of sleep restriction, and to investigate hormones and menstrual phase as predictors of vulnerability to sleep loss. Participants were randomly assigned to a control group in bed 11pm-7am (12 men, 12 follicular women (day 8-14 of cycle), 12 luteal women (day 15-26), 1 active woman) or sleep restriction group in bed 3-7am (13 men, 13 follicular women, 10 luteal women, 1 active woman). Saliva samples were obtained at 10:30 pm (baseline), 7 am, 7:30 am, 4:00 pm, and 4:30 pm to measure the concentration of cortisol, testosterone in men, and estradiol and progesterone in women. N170 and LPP event-related potentials were recorded during emotional face categorization and image categorization tasks respectively. Sleep-restricted participants were less accurate identifying sad facial expressions, and displayed a larger N170 amplitude to sad faces compared to other emotional faces. On the image task, participants had a larger LPP amplitude to positive images compared to neutral, reflecting a positivity bias in attention. Women in the luteal phase displayed more vulnerability to the effects of sleep loss on the image task, supported with multiple relationships with progesterone and poor accuracy in this group. Progesterone may contribute to individual differences in the effects of sleep loss in women. Morning testosterone and cortisol in men, and cortisol in luteal women, were also affected by sleep restriction. Correlations between hormone concentrations and emotion variables support that hormones play a role in emotional processing changes due to sleep loss. Specifically, testosterone and progesterone were associated with sad face accuracy in the sleep restriction group, and cortisol was related to threat processing. Together, the findings of this study indicate that one night of sleep restriction is sufficient to affect emotional processing and the release of hormones. Moreover, menstrual phase played a role in vulnerability to sleep loss. These findings have important implications for understanding the functional role of sleep and hormones in emotion processing.