Sleep inertia associated with a 10-min nap before the commute home following a night shift: A laboratory simulation study. (February 2017)

• Record Type: Journal Article
• Authors: Hilditch, Cassie J.; Dorrian, Jillian; Centofanti, Stephanie A.; Van Dongen, Hans P.; Banks, Siobhan
• Is Part Of: Accident analysis and prevention. Volume 99:Part B (2017)
• Page Start: 411
• Page End: 415
• Publication Date: 2017-02
• Subjects: Alertness -- Fatigue countermeasure -- Nap sleep -- Night shift work -- Psychomotor vigilance test -- Simulated driving; Accidents -- Prevention -- Periodicals; Accident Prevention -- Periodicals; Accidents -- Prévention -- Périodiques; 363.106
• DOI: 10.1016/j.aap.2015.11.010
• Languages: English
• ISSNs: 0001-4575

Abstract

Highlights: A 10-min nap after a night of sleep deprivation resulted in brief sleep inertia. A 40-min driving task performed 5 min after the nap showed no signs of sleep inertia. The 10-min nap did not improve simulated driving performance either. Abstract: Night shift workers are at risk of road accidents due to sleepiness on the commute home. A brief nap at the end of the night shift, before the commute, may serve as a sleepiness countermeasure. However, there is potential for sleep inertia, i.e. transient impairment immediately after awakening from the nap. We investigated whether sleep inertia diminishes the effectiveness of napping as a sleepiness countermeasure before a simulated commute after a simulated night shift. N = 21 healthy subjects (aged 21–35 y; 12 females) participated in a 3-day laboratory study. After a baseline night, subjects were kept awake for 27 h for a simulated night shift. They were randomised to either receive a 10-min nap ending at 04:00 plus a 10-min pre-drive nap ending at 07:10 (10-NAP) or total sleep deprivation (NO-NAP). A 40-min York highway driving task was performed at 07:15 to simulate the commute. A 3-min psychomotor vigilance test (PVT-B) and the Samn-Perelli Fatigue Scale (SP-Fatigue) were administered at 06:30 (pre-nap), 07:12 (post-nap), and 07:55 (post-drive). In the 10-NAP condition, total pre-drive nap sleep time was 9.1 ± 1.2 min (mean ± SD), with 1.3 ± 1.9 min spent in slow wave sleep, as determined polysomnographically. There was no difference between conditions in PVT-B performance at 06:30 (before the nap). In the 10-NAP condition, PVT-B performance was worse after the nap (07:12) compared to before the nap (06:30); no change across time was found in the NO-NAP condition. There was no significant difference between conditions in PVT-B performance after the drive. SP-Fatigue and driving performance did not differ significantly between conditions. In conclusion, the pre-drive nap showed objective, but not subjective, evidence of sleep inertia immediately after awakening. The 10-min nap did not affect driving performance during the simulated commute home, and was not effective as a sleepiness countermeasure.