Impact of Nap Length, Nap Timing and Sleep Quality on Sustaining Early Morning Performance

Abstract

The study examined how nap length, nap timing and sleep quality affect early morning performance (6:00 to 8:00). Twelve students participated in a simulated nightshift schedule (22:00 to 8:00) where the length and timing of nocturnal naps were manipulated (0:00-1:00, 0:00-2:00, 4:00-5:00 and 4:00-6:00). A performance test battery was administered consisting of a psychomotor vigilance test, a logical reasoning test, and a visual analogue scale for subjective fatigue and sleepiness. The results showed that a 120-min nap sustained early morning performance better than a 60-min nap. Taking a nap earlier or later did not affect the neurobehavioral performance tests, although participants slept more efficiently during naps later in the night shift. A negative effect of a nocturnal nap during the night shift on subsequent daytime and nocturnal sleep was not observed in the sleep architecture. It still remains unclear whether slow wave sleep plays an important role in sustaining early morning performance. In terms of work safety and sleep health, the results suggest that a longer and later nap is beneficial during night shifts.

Measures to counteract the negative effects of night work

“…Several studies have shown that naps increase performance on objective measures of sleepiness such as vigilance and time reaction tests (114)(115)(116)(117). Studies on the effects of naps during night work have also shown improvement on measures of subjective sleepiness (114,116,(118)(119)(120).…”

Electrophysiological correlates of cognition improve with nap during sleep deprivation

“…Night-shift work can cause not only occupational accidents due to severe sleepiness but also can introduce several health problems (Folkard and Tucker 2003). Taking a nap is one of the eVective countermeasures to prevent increasing sleepiness and decreasing alertness during sleep deprivation (Kubo et al 2007). Previous research related to nightshifts has examined various kinds of napping strategies to counteract the problem among night shift workers; one such strategy is taking a prophylactic nap before the night of sleep deprivation.…”

Brief Hourly Exercise during Night Work can Help Maintain Workers' Performance

“…Work performance has been used as a behavioural index of fatigue 21,39) , and cumulative workload induced fatigue was expressed as a transient decrease in work performance. However, it should be borne in mind that work performance is affected by a number of factors, such as sustained attention, circadian rhythms and extrinsic and intrinsic motivation 7,40,41) . Therefore, interactions among these factors make it difficult to interpret data on work performance.…”

“…Therefore, identification of effective measures to counteract the fatigue and sleepiness associated with night work has become an important focus of investigation in the field of occupational health. The effectiveness of naps 7,8) , caffeine 9) , ventilation 10) , bright light 11) and music 12) as measures to combat the adverse effects of night work has been examined in previous studies.…”