Preventive effects of self-awakening on sleep inertia a short nap

Abstract

A short nap is effective to prevent the afternoon arousal reduction (i.e., post lunch dip). However, sleep inertia remains just after awakening from nap. This study examined whether the self-awakening prevent sleep inertiaafter short nap. 10 healthy graduated students participated in the study. They took a nap from 14 : 00 for around 15 min in the self-awakening condition or for 20min in the forcedawakening condition from lights off. A 5-min session consisting of auditory oddball task (4min) and Visual analog scale (VAS : lmin) was carried out continuously twice (10min) before and six times (30min) after the nap. P300 amplitude of the event related potential was used to evaluate arousal levels. The VAS was used to evaluate feeling of sleepiness. P300 amplitudes during postnap sessions reduced significantly in the forcedawakening condition, while such reduction was not observed in the self-awakening condition. These results indicated that the arousal level after the nap was lower in the forced-awakening than the self-awakening condition. For the VAS scores, a feeling of sleepiness was improved after the nap. Especially, the improvement was greater in the self-awakening than forced-awakening condition. These results suggest that self-awakening was effective to reduce a post nap sleep inertia.