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Abstract
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STUDY OBJECTIVES: To assess sleep inertia following 10-min and 30-min naps during a simulated night shift.
METHODS: Thirty-one (31) healthy adults (aged 21-35 y; 18 females) participated in a 3-day laboratory study that included one baseline (BL) sleep (22:00-07:00) and one experimental night involving randomization to either: total sleep deprivation (NO-NAP), a 10-min nap (10-NAP) or a 30-min nap (30-NAP). Nap opportunities ended at 04:00. A 3-min psychomotor vigilance task (PVT-B), digit-symbol substitution task (DSST), fatigue scale, sleepiness scale, and self-rated performance scale were undertaken prenap (03:00) and at 2, 17, 32, and 47 min postnap.
RESULTS: The 30-NAP (14.7 ± 5.7 min) had more slow wave sleep than the 10-NAP (0.8 ± 1.5 min; P < 0.001) condition. In the NO-NAP condition, PVT-B performance was worse than prenap (4.6 ± 0.3 1/sec) at 47 min postnap (4.1 ± 0.4 1/sec; P < 0.001). There was no change across time in the 10-NAP condition. In the 30-NAP condition, performance immediately deteriorated from prenap (4.3 ± 0.3 1/sec) and was still worse at 47 min postnap (4.0 ± 0.5 1/sec; P < 0.015). DSST performance deteriorated in the NO-NAP (worse than prenap from 17 to 47 min; P < 0.008), did not change in the 10-NAP, and was impaired 2 min postnap in the 30-NAP condition (P = 0.028). All conditions self-rated performance as better than prenap for all postnap test points (P < 0.001).
CONCLUSIONS: This study is the first to show that a 10-min - but not a 30-min - nighttime nap had minimal sleep inertia and helped to mitigate short-term performance impairment during a simulated night shift. Self-rated performance did not reflect objective performance following a nap.
Language: en |