'Power naps' — brief periods of daytime sleep lasting an hour or less — improve alertness, productivity and mood, but their effect on previously learned information has been unclear. In 28 May Advanced Online Nature Neuroscience, Sara Mednick and colleagues from Harvard University, show that a short 60 minutes daytime nap may contribute to the consolidation of learning and improve performance of visual discrimination tasks (DOI:10.1038/nn864).

Using visual texture discrimination tasks Mednick et al. tested human subjects on four occasions on the same day and observed that for repeated, within-day testing, perceptual thresholds deteriorated progressively across the four test sessions. This performance deterioration was prevented either by having the subjects take a mid-day nap between the second and third sessions, or by shifting the target stimuli to an untrained region of visual space.

The authors conclude "the psychological sensation of 'burnout,' described anecdotally as increased irritation and frustration along with decreased effectiveness after prolonged cognitive effort, may not reflect a general mental fatigue, but rather the specific need of an overused local neural network to enjoy the restorative benefits of sleep."