2019 Volume 95 Issue 2 Pages 56-67
This study investigated the effects of the use of a chair for the short nap on sleep quality, task performance, and drowsiness. The participants were 10 healthy males (average age ± SD, 22.3 ± 4.3 years). They napped for 20 minutes (12:35–12:55) after lunch in a chair (chair condition) and in a bed (bed condition) at intervals of more than 1 week. On the basis of our previous study, the back, seat, and leg rest angles in the chair to the horizontal axis were set as 30, 20, and 0 degrees, respectively. Polysomnography (EEG, EOG, and ECG) was performed, and task performance (choice reaction task and logic task) and mental work strain (MWS) were measured. The data from 6 participants (20.8 ± 1.6 years) were analyzed, who succeed- ed in the controlled nocturnal sleep for 5 hours before the day of the experiment. The frequency of waking in chair condition was significantly higher than it in bed condition (p < 0.05). For chair condition, the sleep latency was 4.7 min and total sleep time was 13.4 min; slow-wave sleep occurred for 0.42 min. For both conditions, the drowsiness score significantly decreased after the nap (p < 0.001). The results for average heart rate, choice reaction task and logic task did not have significant differences between chair and bed condition. The results show that the use of a chair for the short nap has the potential to prevent deep sleep during the nap and drowsiness after the nap.