Article

The Nighttime Nap Strategies for Improving Night Shift Work in Workplace

Nagoya City University, Nagoya, Aichi, Japan
Industrial Health (Impact Factor: 1.12). 02/2005; 43(1):24-9. DOI: 10.2486/indhealth.43.24
Source: PubMed

ABSTRACT

Nighttime napping is an effective measure to prevent adverse effects due to night shift work. A characteristic of nighttime nap is that it can result in considerably deeper sleep. Several studies have shown that taking nighttime naps suppressed increasing sleepiness, decreasing alertness during the period following awaking from a nap, and prevented disturbance of circadian rhythm ("anchor sleep"). The length of daytime sleep after night shift, when combined with a nighttime nap, is shorter than that without nap. This finding might be interpreted as a beneficial effect rather than a negative feature because workers can then spend time engaged in other activities rather than sleeping. Nevertheless, the introduction of nighttime sleep break in the workplace has not been widely accepted. To promote nighttime napping strategy in the workplace, consensus building while acting on conflicting interest is essential. Recently, participatory method for improvement of working condition has expanded worldwide. A characteristic of the activity is using action checklist and group work, and heightening motivation to improvement working condition between worker and manager. Through the activities, nighttime napping strategy would be spread more in the workplaces and play a role as one of the effective tools for improving working conditions, work performance and safety in the future.

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    • "When the main sleep period is restricted or absent, adding supplementary naps improves alertness and performance (Bonnet, 1991; Dinges et al., 1987; Ficca et al., 2010; Sallinen et al., 1998; Takeyama et al., 2005). The term ''split sleep'' means two or more sleep opportunities in a 24-h period, ranging from a main sleep and a supplemental nap (e.g. 6 and 2 h), through a main sleep and several naps, to multiple naps with no clear main sleep (Belenky et al., 2008, 2011; Bonnet & Arand, 2003; Takeyama et al., 2005). Spilt sleep schedules are common practice in a number of industries including healthcare, maritime and transport. "
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    ABSTRACT: Shift work is common in today's society, and is associated with negative health outcomes, and accidents and incidents. These detrimental effects can be primarily attributed to sleeping and working at an adverse circadian time. The aim of this study was to examine whether a split sleep schedule is as effective as a consolidated day shift or night shift schedule for maintaining performance and sustaining sleep. Fifty-three healthy male volunteers (mean ± SD age ¼ 26.51 ± 4.07 years) underwent a randomized three condition study design. A split sleep condition involving two 5-h sleeping opportunities in 24 h [time in bed (TIB) 0300 h–0800 h and 1500 h–2000 h] was compared to a 10-h consolidated nighttime sleep (TIB 2200 h–0800 h) and 10-h consolidated daytime sleep (TIB 1000 h–2000 h). All participants underwent a baseline period of 10 h of nocturnal time in bed (TIB) followed by a 5-d simulated workweek spent in one of the three conditions. Polysomnography, psychomotor vigilance task, digit-symbol substitution task and subjective state were assessed. During the 5-d simulated workweek, participants in the nighttime sleep condition slept the most (total sleep time per day (TST) 8.4 h ± 13.4 min), followed by the split sleep condition (TST 7.16 h ± 14.2 min) and the daytime sleep condition (TST 6.4 h ± 15.3 min). Subjective sleepiness was highest in the daytime sleep condition and lowest in the nighttime sleep condition. No significant differences in performance were observed between the conditions. Compared to a nighttime consolidated sleep opportunity or split sleep, placement of a consolidated sleep opportunity during the day yielded truncated sleep and increased sleepiness. Further research in real-world situations is warranted to fully assess the efficacy of alternative split sleep schedules for improving safety and productivity.
    Full-text · Article · Jul 2014 · Chronobiology International
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    • "Because data for both shiftworkers and day workers were used in their analysis, they clearly showed the risk factors of SWD across the nurses with different work schedules. However, their study could not explore the association between SWD and the work-related factors specific to shiftworkers , such as the existence or absence of nighttime nap opportunities, which have been reported to be associated with shiftworkers' sleepiness during night work, wellbeing , and sleep-related problems such as excessive sleepiness (Purnell et al., 2002; Sallinen et al., 1998; Smith et al., 2007; Takeyama et al., 2005). "
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    ABSTRACT: Workers who meet the criteria for shift work disorder (SWD) have elevated levels of risk for various health and behavioral problems. However, the impact of having SWD on shiftworkers engaged in rapid-rotation schedules is unknown. Moreover, the risk factors for the occurrence of SWD remain unclear. To clarify these issues, we conducted a questionnaire-based, cross-sectional survey on a sample of shiftworking nurses. Responses were obtained from 1202 nurses working at university hospitals in Tokyo, Japan, including 727 two-shift workers and 315 three-shift workers. The questionnaire included items relevant to age, gender, family structure, work environment, health-related quality of life (QOL), diurnal type, depressive symptoms, and SWD. Participants who reported insomnia and/or excessive sleepiness for at least 1 mo that was subjectively relevant to their shiftwork schedules were categorized as having SWD. The prevalence of SWD in the sampled shiftworking nurses was 24.4%; shiftworking nurses with SWD showed lower health-related QOL and more severe depressive symptoms, with greater rates of both actual accidents/errors and near misses, than those without SWD. The results of logistic regression analyses showed that more time spent working at night, frequent missing of nap opportunities during night work, and having an eveningness-oriented chronotype were significantly associated with SWD. The present study indicated that SWD might be associated with reduced health-related QOL and decreased work performance in shiftworking nurses on rapid-rotation schedules. The results also suggested that missing napping opportunities during night work, long nighttime working hours, and the delay of circadian rhythms are associated with the occurrence of SWD among shiftworking nurses on rapid-rotation schedules. (Author correspondence: yuinoue@tokyo-med.ac.jp ).
    Full-text · Article · Feb 2013 · Chronobiology International
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    • "Previous research has identified napping as a beneficial way of attenuating the effects of sleepiness, while improving performance at night (Matsumoto and Morita 1987;Takahashi, Fukuda, and Arito 1999;Della Rocco et al. 2000;Bonnefond et al. 2001;Takeyama, Kubo, and Itani 2005;Phillip et al. 2006;Kubo et al. 2007;Smith et al. 2007;Roach et al. 2011;Kaida, Takeda, and Tsuzuki 2012). Disturbances to the circadian rhythm can be ameliorated through strategic napping, while the homeostatic sleep pressure associated with being awake for extended periods of time is reduced (Haslam 1985;Takeyama, Kubo, and Itani 2005;Smith et al. 2007). Naps can take two forms: prophylactic naps occur prior to the sleep loss (Lavie and Weler 1989;Bonnet and Arand 1995;Takeyama et al. 2002;Lovato et al. 2009) while reactive naps are taken during the sleep loss period or night shift (Matsumoto and Harada 1994;Rosekind et al. 1995;Saito and Sasaki 1996;Purnell, Feyer, and Herbison 2002;Takeyama et al. 2002;Lovato et al. 2009). "
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    ABSTRACT: Unlabelled: This study compared the effects of a 1 h self-selected recovery period to those of a standard night shift arrangement (with a total break time of 1-h) over a simulated three-day night shift schedule in a laboratory setting. Results showed that the inclusion of the flexible nap scheme resulted in higher performance output, improvements in physiological strain responses and reduced sleepiness during each night shift and generally over the three-night cycle. Certain variables also revealed the impact of napping compared with the standard rest break condition on the circadian rhythm. The sleep diary records show that the inclusion of the current intervention did not significantly reduce daytime recovery sleep. The results suggest that the potential benefits of flexible napping may outweigh the logistical effort it requires in a workplace environment. Practitioner summary: Consensus on appropriate napping strategies for shift work remains a challenge. This simulated night shift laboratory study sought to determine the effects of a 1-h self-selected nap opportunity relative to a normal shift set-up. The nap improved performance and decreased sleepiness, without affecting daytime sleep.
    Full-text · Article · Feb 2013 · Ergonomics
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