title: Effects of an afternoon nap on nighttime alertness and performance in long-haul drivers.
abstract: The effects of an afternoon nap on alertness and psychomotor performance were assessed during a simulated night shift. After a night of partial sleep restriction, eight professional long-haul drivers either slept (nap condition) or engaged in sedentary activities (no-nap condition) from 14:00 to 17:00 h. Alertness and performance testing sessions were conducted at 12:00 (pre-nap baseline), 24:00, 02:30, 05:00 and 07:30 h, and followed 2-h runs in a driving simulator. In the nap condition, the subjects showed lower subjective sleepiness and fatigue, as measured by visual analog scales, and faster reaction times and less variability on psychomotor performance tasks. Electrophysiological indices of arousal during the driving runs also reflected the beneficial effects of the afternoon nap, with lower spectral activity in the theta (4-7.75 Hz), alpha (8-11.75 Hz) and fast theta-slow alpha (6-9.75 Hz) frequency bands of the electroencephalogram, indicating higher arousal levels. Thus, a 3-h napping opportunity ending at 17:00 h improved significantly several indices of alertness and performance measured 7-14 h later.
authors.affiliation: Institute for Circadian Physiology, White Plains, NY 10605, USA. mm1706@columbia.edu
authors.forename: M Mila
authors.initials: MM
authors.lastname: Macchi
authors.forename: Ziad
authors.initials: Z
authors.lastname: Boulos
authors.forename: Thomas
authors.initials: T
authors.lastname: Ranney
authors.forename: Lucinda
authors.initials: L
authors.lastname: Simmons
authors.forename: Scott S
authors.initials: SS
authors.lastname: Campbell
mesh_terms: D000328:Adult; D001143:Arousal / Q000502:physiology*; D001334:Automobile Driving; D002940:Circadian Rhythm; D004569:Electroencephalography; D005221:Fatigue; D005260:Female; D006801:Humans; D008297:Male; D018986:Motor Vehicles; D011597:Psychomotor Performance / Q000502:physiology*; D012890:Sleep / Q000502:physiology*; D012892:Sleep Deprivation; D013995:Time; D014851:Wakefulness