The purpose of this study was to evaluate the influence of sleep deprivation on emotional expression and subjective emotional experience in a highly controlled, laboratory setting. Twenty-three healthy adult participants watched positive (amusing) and negative (sad) film clips before and after they were randomly assigned to a night of sleep deprivation or a normal sleep control condition. The intensity of their facial expressiveness while viewing the films was coded by human judges and compared to their subjective emotional responses. Relative to the control group, sleep-deprived participants demonstrated less expressiveness, especially in response to positive stimuli. Subjective responses were not significantly different between the sleep-deprived and control groups. These preliminary results suggest that sleep deprivation is associated with attenuated emotional expressiveness in healthy adults.