The effects of short afternoon nap and bright light on task switching performance and error-related negativity

The aim of the present study was to demonstrate the effects of a short nap (20 min) and bright light (>2000 lux) in the afternoon on task switching ability (i.e., switch cost and mixing cost) and error-related negativity (Ne/ERN). The effects of a short nap and bright light on task switching performance have been less reported despite the importance and frequency of task switching as a common activity in many occupational situations. Sixteen volunteers performed a switching task twice a day (1200–1330 h and 1430–21600 h). Participants completed a total of four experimental conditions (control, short nap, bright light, and short nap with bright light). A short nap was taken during the break between the first and second tasks. During the second task, bright light treatment was applied in two of the four conditions. A short afternoon nap improved task-switching performance (i.e., switch cost) and enlarged Ne/ERN amplitude. No effects were found for light conditions on task-switching performance and Ne/ERN amplitude. The results suggest that: (i) a short afternoon nap improves executive functions and self-monitoring that involve the prefrontal cortex; and (ii) the effect of bright light on task-switching performance is smaller compared to a short nap.