The effects of modafinil, caffeine, and dextroamphetamine on judgments of simple versus complex emotional expressions following sleep deprivation.

Cognitive abilities such as vigilance, attention, memory, and executive functioning can be degraded significantly following extended periods of wakefulness. Although much evidence suggests that sleep-loss induced deficits in alertness and vigilance can be reversed or mitigated by stimulants such as caffeine, it is not clear how these compounds may affect other higher level cognitive processes such as emotional perception and judgment. Following 47 h of sleep deprivation, the study examined the effect of three stimulant medications (modafinil 400 mg, dextroamphetamine 20 mg, caffeine 600 mg) or placebo on the ability of 54 healthy participants to discriminate and label simple emotional expressions versus complex affect blends (created by morphing photographs of two different affective facial expressions). For simple affective faces, neither sleep loss nor stimulant medications made any difference on the accuracy of judgments. In contrast, for complex emotion blends, all three stimulant medications significantly improved the ability to discriminate subtle aspects of emotion correctly relative to placebo, but did not differ from one another. These findings suggest that all three stimulant medications are effective at restoring some aspects of subtle affective perception.