No first night shift effect observed following a nocturnal main sleep and a prophylactic 1-h afternoon nap

Kosmadopoulos, Anastasi; Zhou, Xuan; Roach, Gregory D.; Darwent, David; Sargent, Charli

doi:10.3109/07420528.2016.1167727

Cited by 6 publications

(6 citation statements)

References 16 publications

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“…Across the night-shift days, total sleep duration was shortest in the 24 h comprising the first night shift and then stabilized at longer durations for subsequent shifts. This pattern is consistent with the acute sleep deprivation often associated with the transition from a diurnal to nocturnal schedule (Santhi et al, 2007; Kosmadopoulos et al, 2016). Indeed, as many as 50% of workers do not nap immediately prior to their first night shift, thereby accumulating as much as 24 h of wakefulness by its end the following day (Knauth et al, 1980).…”

Section: Discussionsupporting

confidence: 84%

Circadian Adaptation of Melatonin and Cortisol in Police Officers Working Rotating Shifts

Kosmadopoulos,

Boudreau,

Kervezee

et al. 2023

J Biol Rhythms

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Misalignment of behavior and circadian rhythms due to night work can impair sleep and waking function. While both simulated and field-based studies suggest that circadian adaptation to a nocturnal schedule is slow, the rates of adaptation in real-world shift-work conditions are still largely unknown. The aim of this study was to evaluate the extent of adaptation of 24-h rhythms with 6-sulfatoxymelatonin (aMT6s) and cortisol in police officers working rotating shifts, with a special attention to night shifts. A total of 76 police officers (20 women; aged 32 ± 5.4 years, mean ± SD) from the province of Quebec, Canada, participated in a field study during their 28- or 35-day work cycle. Urine samples were collected for ~32 h before a series of day, evening, and night shifts to assess circadian phase. Before day, evening, and night shifts, 60%-89% of officers were adapted to a day schedule based on aMT6 rhythms, and 71%-78% were adapted based on cortisol rhythms. To further quantify the rate of circadian adaptation to night shifts, initial and final phases were determined in a subset of 37 officers with suitable rhythms for both hormones before and after 3-8 consecutive shifts (median = 7). Data were analyzed with circular and linear mixed-effects models. After night shifts, 30% and 24% of officers were adapted to a night-oriented schedule for aMT6s and cortisol, respectively. Significantly larger phase-delay shifts (aMT6s: −7.3 ± 0.9 h; cortisol: −6.3 ± 0.8 h) were observed in police officers who adapted to night shifts than in non-adapted officers (aMT6s: 0.8 ± 0.9 h; cortisol: 0.2 ± 1.1 h). Consistent with prior research, our results from both urinary aMT6s and cortisol midpoints indicate that a large proportion of police officers remained in a state of circadian misalignment following a series of night shifts in dim-light working environments.

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Section: Discussionsupporting

confidence: 84%

Circadian Adaptation of Melatonin and Cortisol in Police Officers Working Rotating Shifts

Kosmadopoulos,

Boudreau,

Kervezee

et al. 2023

J Biol Rhythms

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“…Future studies could investigate whether potential benefits of a shorter period of prior wake outweighs the effects of sleep loss and are associated with improved night shift performance for early chronotypes using a strategically delayed sleep. Future research could also assess the impact of chronotype on the effect of a delayed main sleep combined with a nap, as daytime naps alleviate sleep pressure and improve performance during the first night shift (Akerstedt, 2003; Åkerstedt, 1998; Boivin & Boudreau, 2014; Harma et al, 1989; Kosmadopoulos et al, 2016; Macchi et al, 2002; Mchill & Wright Jr., 2019; Purnell et al, 2002). As chronotype shows a relationship with sex (Roenneberg et al, 2003), future studies could also examine differences between males and females in the effects of chronotype on sleep during normally timed and delayed sleep opportunities.…”

Section: Discussionmentioning

confidence: 99%

The night before night shift: Chronotype impacts total sleep and rapid eye movement sleep during a strategically delayed sleep

Reiter

Roach

Sargent

2022

Journal of Sleep Research

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Summary Transition to night shift may be improved by strategically delaying the main sleep preceding a first night shift. However, the effects of delayed timing on sleep may differ between chronotypes. Therefore, the study aim was to compare the impacts of chronotype on sleep quality and architecture during a normally timed sleep opportunity and a delayed sleep opportunity. Seventy‐two (36 female, 36 male) healthy adults participated in a laboratory study. Participants were provided with a normally timed sleep opportunity (23:00–08:00) and a delayed sleep opportunity (03:00–12:00) over two consecutive nights in a sleep laboratory. Sleep was monitored by polysomnography (PSG), and chronotype was determined from dim light melatonin onset (DLMO). A tertile split of DLMO defined early (20:24 ± 0:42 h), intermediate (21:31 ± 0:12 h), and late chronotype (22:56 ± 0:54 h) categories. Although there was no main effect of chronotype on any sleep measure, early chronotypes obtained less total sleep with delayed sleep than with normally timed sleep (p = 0.044). Intermediate and late chronotypes obtained more rapid eye movement (REM) sleep with delayed sleep than with normally timed sleep (p = 0.013, p = 0.012 respectively). Wake was more elevated for all chronotypes in the later hours of the delayed sleep opportunity than at the start of the sleep opportunity. Strategically delaying the main sleep preceding a first night shift appears to benefit intermediate and late chronotypes (i.e., more REM sleep), but not early chronotypes (i.e., less total sleep). Circadian processes appear to elevate wakefulness for all chronotypes in the later stages of a delayed sleep opportunity.

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“…Another explanation for why several subsequent night shifts was not necessarily worse than one single night, 13 may be related to findings that neurobehavioural impairment on the first night shift is often greater than on subsequent night shifts, due to extended wakefulness. 35 QRs was not associated with pain complaints in the present group of nurses, indicating that an evening-to-morning transition was not more detrimental than two consecutive morning shifts. QRs in rotating shift work has been found to reduce sleep duration and was associated with more health complaints than not working QRs.…”

Section: Discussionmentioning

confidence: 46%

Section: Discussionmentioning

confidence: 99%

Pain complaints after consecutive nights and quick returns in Norwegian nurses working three-shift rotation: an observational study

et al. 2020

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ObjectivesTo determine whether nurses working consecutive night shifts, or short transitions between shifts (quick returns (QRs)), yielded higher risk for pain complaints when compared with regular morning shifts. Sleep duration was tested as a potential mediator.DesignObservational diary study.SettingRandom hospitals.ParticipantsNurses with three-shift rotation (morning, evening and night), n=679, 22–63 years old.Outcomes measuresDaily ratings of working hours, sleep and subjective pain complaints in six anatomical regions (head, neck/shoulder/upper back, upper extremity, low back, lower extremity and abdomen) for 28 days. In addition, we assessed demographics, habitual sleep and pain complaints, work and lifestyle factors. It was tested (1) whether the risk for pain complaints was higher after workday 3 versus after workday 2, and whether the difference was larger for consecutive night shifts versus consecutive morning shifts, and (2) whether the risk for pain complaints was higher after QRs versus after two morning shifts. Risk for pain complaints refers to combined increased risk for any pain and risk for increased intensity.ResultsAdjusted analyses showed no shift type by workday interaction for pain complaints in the neck/shoulder/upper back, upper extremities, low back, lower extremities or abdomen. For headache, a strong trend indicated that the risk was higher on workday 3 compared with workday 2 for night shifts (OR 1.13, 95% CI 0.99 to 1.28). The risk was lowered if sleep duration was taken into account (OR 0.37, 95% CI 0.17 to 0.81). No conclusive support was found for the risk for pain complaints being higher after QRs, compared with after morning shifts.ConclusionsFor five of six pain complaints, the hypotheses were not supported by the current data. For headache, we found potential support for a sleep-relieving effect on headache after working several nights in a row. Pain complaints were not instigated or exacerbated by an evening-to-morning transition between shifts.

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No first night shift effect observed following a nocturnal main sleep and a prophylactic 1-h afternoon nap

Cited by 6 publications

References 16 publications

Circadian Adaptation of Melatonin and Cortisol in Police Officers Working Rotating Shifts

Circadian Adaptation of Melatonin and Cortisol in Police Officers Working Rotating Shifts

The night before night shift: Chronotype impacts total sleep and rapid eye movement sleep during a strategically delayed sleep

Pain complaints after consecutive nights and quick returns in Norwegian nurses working three-shift rotation: an observational study

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