Chronotype-specific Sleep in Two Versus Four Consecutive Shifts

The study aimed to explore chronotype-specific effects of two versus four consecutive morning or night shifts on sleep-wake behavior. Sleep debt and social jetlag (a behavioral proxy of circadian misalignment) were estimated from sleep diary data collected for 5 weeks in a within-subject field study of 30 rotating night shift workers (29.9 ± 7.3 years, 60% female). Mixed models were used to examine whether effects of shift sequence length on sleep are dependent on chronotype, testing the interaction between sequence length (two vs. four) and chronotype (determined from sleep diaries). Analyses of two versus four morning shifts showed no significant interaction effects with chronotype. In contrast, increasing the number of night shifts from two to four increased sleep debt in early chronotypes, but decreased sleep debt in late types, with no change in intermediate ones. In early types, the higher sleep debt was due to accumulated sleep loss over four night shifts. In late types, sleep duration did not increase over the course of four night shifts, so that adaptation is unlikely to explain the observed lower sleep debt. Late types instead had increased sleep debt after two night shifts, which was carried over from two preceding morning shifts in this schedule. Including naps did not change the findings. Social jetlag was unaffected by the number of consecutive night shifts. Our results suggest that consecutive night shifts should be limited in early types. For other chronotypes, working four night shifts might be a beneficial alternative to working two morning and two night shifts. Studies should record shift sequences in rotating schedules.

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Social jetlag and sleep debts are altered in different rosters of night shift work

PLoS ONE ◽

10.1371/journal.pone.0262049 ◽

2022 ◽

Vol 17 (1) ◽

pp. e0262049

Author(s):

Swaantje Casjens ◽

Frank Brenscheidt ◽

Anita Tisch ◽

Beate Beermann ◽

Thomas Brüning ◽

...

Keyword(s):

Sleep Quality ◽

Sleep Deprivation ◽

Sleep Duration ◽

Shift Work ◽

Night Shift ◽

Shift Workers ◽

Social Jetlag ◽

Sleep Debt ◽

The Impact ◽

Night Shifts

Background Night and shift work are suspected to cause various adverse effects on health and sleep. Sleep deprivation through shift work is assumed to be compensated on free days. So far it is not clear how different shift systems and shift lengths affect sleep structure on work and free days. Especially working night shifts disrupts the circadian rhythm but also extended working hours (12h) might affect sleep characteristics. Hitherto, the magnitude of sleep debt, social jetlag, and Locomotor Inactivity During Sleep (LIDS) in different shift systems is unknown. Methods Here, we investigated the impact of five different shift rosters on sleep in 129 industrial workers from Germany. Permanent night work with multiple shift systems with and without night shifts and with different shift lengths were compared. Wrist-activity was monitored over 28 days revealing sleep on- and offsets as well as LIDS as proxy for sleep quality. Overall, 3,865 sleep bouts comprising 22,310 hours of sleep were examined. Results The mean daily age-adjusted sleep duration (including naps) was 6:43h and did not differ between shift workers of different rosters. However, sleep duration on workdays was particularly low in rotational shift systems with 12h-shifts (5:00h), while overall sleep debt was highest. Shift workers showed a median absolute social jetlag of 3:03h, which differed considerably between shift types and rosters (p<0.0001). Permanent night workers had the highest social jetlag (5:08h) and latest mid-sleeps on workdays and free days. Sleep quality was reduced in permanent night shift workers compared with shift workers in other rosters and differed between daytime and nighttime sleep. Conclusions Shift work leads to partial sleep deprivation, which particularly affects workers in 12h-shifts and permanent night shifts. Working these shifts resulted in higher sleep debts and larger absolute social jetlag whereas sleep quality was especially reduced in permanent night shift workers compared with shift workers of other rosters.

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61. Can Melatonin Improve Adaptation To Night Shift? A Pilot Study Using an Urban EMS System

Prehospital and Disaster Medicine ◽

10.1017/s1049023x0004574x ◽

1996 ◽

Vol 11 (S2) ◽

pp. S34-S34

Author(s):

Michael Tremea ◽

Mark James ◽

Jeffrey Jones ◽

Jon Krohmer

Keyword(s):

Job Performance ◽

Night Shift ◽

Biological Clock ◽

Consecutive Night ◽

Sleep Diaries ◽

Visual Analog Scales ◽

Significant Difference ◽

Clinical Benefits ◽

Double Blinded ◽

Night Shifts

Purpose: To determine whether melatonin (N-acetyl-5-methoxytryptamine) is effective in helping prehospital personnel working consecutive night shifts reset their biological clock and minimize circadian rhythm disruption.Methods: A double-blinded, randomized, cross-over study was performed using 12 paramedic volunteers. Paramedics were working a span of consecutive night (2300-0700) shifts and received either a melatonin capsule (6 mg) or placebo to be taken prior to each of the consecutive day sleeps. Each participants completed a total of four spans of consecutive night shifts (2-melatonin, 2-placebo). Collected data included daily sleep diaries, quantification of alcohol/caffeine consumed, and possible drug side-effects. Assessment of job performance, mood and alertness were measured every day using 10-cm visual analog scales (VAS).Results: Analysis of sleep diaries demonstrated no significant difference (p >0.05) between the two treatments in respect to mean sleep latency (melatonin = 15.4 min. vs. placebo = 14.6 min), mean sleep duration (melatonin = 6.7 hrs. vs. placebo = 6.9 hrs), or subjectively rated sleep quality (melatonin = 5.8 VAS vs placebo = 5.6 VAS). Similarly, no significant benefits were noted between the mean VAS scores for daily job performance, mood and alertness. Adverse effects were rare, one patient taking melatonin reported a prolonged sedative effect.Conclusion: Despite widespread belief in the benefits of melatonin as a hypnotic agent, no clinical benefits were noted in terms of daytime sleep or job performance in paramedics working consecutive night shifts.

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The Association Between the Number of Consecutive Night Shifts and Insomnia Among Shift Workers: A Multi-Center Study

Frontiers in Public Health ◽

10.3389/fpubh.2021.761279 ◽

2021 ◽

Vol 9 ◽

Author(s):

Juho Sim ◽

Byung-Yoon Yun ◽

Jiho Lee ◽

Sung Kyung Kim ◽

Seunghyun Lee ◽

...

Keyword(s):

Data Model ◽

Sleep Problems ◽

Night Shift ◽

Common Data Model ◽

Consecutive Night ◽

Multivariate Logistic Regression ◽

Shift Workers ◽

Multi Center Study ◽

Night Shifts ◽

Center Study

Objectives: There is a need to determine the optimal limit of consecutive night shift work to reduce insomnia caused by the accumulation of sleep problems among night shift workers. This study aimed to investigate the prevalence of insomnia caused by consecutive night shifts and evaluate the night shift duration that worsens insomnia the most, using a large amount of medical examination data.Methods: Night shift profiles and baseline demographics data of three hospitals were collected from January 2015 to December 2017. For subjects who had been examined more than once at the same institution, information corresponding to the most recent date was used. Multivariate logistic regression was performed to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Pooled ORs were calculated by using the results of the three institutions.Results: Of the 33,669 participants, 31.3% were female. The average age was 41.1 ± 11.1 years and the prevalence of insomnia was 38.7% (n = 13,025). After adjusting for potential confounders and compared to workers who reported not working in consecutive night shifts, odds of insomnia were greatest among workers reporting working three consecutive nights (OR 2.65, 95% CI 1.97–3.56) followed by those working two nights (OR 1.81, 95% CI 1.45–2.26), five nights (OR 1.78, 95% CI 1.56–2.03), and four nights (OR 1.68, 95% CI 1.55–1.82).Conclusion: Our study demonstrates a significant relationship between consecutive night shift and insomnia with multicenter examination data, using common data model. This study could be a basis for establishing policies and guidelines that improve night shift workers' health.

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Sleep Quality in Nurses

Biological Research For Nursing ◽

10.1177/1099800412439459 ◽

2012 ◽

Vol 15 (3) ◽

pp. 273-279 ◽

Cited By ~ 9

Author(s):

Shu-Fen Niu ◽

Hsin Chu ◽

Min-Huey Chung ◽

Chun-Chieh Lin ◽

Yu-Shiun Chang ◽

...

Keyword(s):

Sleep Quality ◽

Medical Center ◽

Night Shift ◽

Sleep Time ◽

Shift Workers ◽

Sleep Diaries ◽

Shift Group ◽

Sleep Parameters ◽

The Difference ◽

Night Shifts

The study investigated the number of days off nurses working night shifts need to recover their sleep quality to the level of daytime workers during their days off. This study included 30 day-shift nurses and 32 night-shift nurses. It was conducted as a randomized clinical trial in the medical and surgical wards of a medical center in northern Taiwan in May and June 2010 using sleep diaries and sleep parameters collected by actigraphy on different workdays and days off. On workdays, the night-shift group had significantly less total sleep time (TST) on Day 5 and significantly lower sleep efficiency (SE) on Day 3 than the day-shift group. TSTs of the two groups on days off were higher than those on workdays. On the 4th consecutive day off, higher TST, a decrease in WASO, and an increase in SE suggests that the night-shift group had recovered their sleep quality to the level of the day-shift group on their days off. The SE of the night-shift group exceeded that of the day-shift group after the 4th consecutive day off, though the difference was not statistically significant in the present study. Based on these data, it is recommended that night-shift workers arrange a period of at least 4 days off after 5 consecutive night shifts and at least 5 days off if the staff who have previously worked night shifts are being assigned a set of different shifts.

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Disturbances of Autonomic Regulation of Cardiovascular System at Different Working Regimes with Night Shifts

Kardiologiia ◽

10.18087/cardio.2020.9.n1134 ◽

2020 ◽

Vol 60 (9) ◽

pp. 62-67

Author(s):

Yu. A. Merkulov ◽

A. A. Pyatkov ◽

S. G. Gorokhova ◽

D. M. Merkulova ◽

O. Yu. Atkov

Keyword(s):

Shift Work ◽

Spectral Characteristics ◽

Night Shift ◽

Autonomic Regulation ◽

Total Power ◽

Orthostatic Test ◽

Heart Rhythm Variability ◽

Shift Workers ◽

Rotating Shift Work ◽

Night Shifts

Aim To study temporal and spectral characteristics of heart rhythm variability (HRV) in night shift workers.Materials and methods Along with traditional risk factors, conditions of labor contribute to development of cardiovascular morbidity, including night shift work, which can be associated with disorders of the autonomic regulation detected by analysis of HRV. This study included 100 healthy men. 74 of them were engaged in shift work, including 53 men with rotating shift work, 21 men with fixed night shifts, and 26 men with day-time work. HRV was analyzed by data of 5-min electrocardiogram recording (background recording and orthostatic test).Results Night-shift workers had decreases in total power of regulation (ТР, SDNN) and in the parasympathetic branch (HF, pNN50). Rotating night-shift workers displayed significant decreases in SDNN and pNN50 and pronounced changes in the VLF / LF / HF ratio in the orthostatic test.Conclusion In work with night shifts, the type of autonomic regulation differs from the “standard” functioning of the autonomic nervous system (ANS). This study showed different effects of night work regimens on HRV indexes. With the rotating shift work, the ANS dysregulation was more profound and was evident by a significant decrease in the ANS total tone and parasympathetic activity (SDNN, pNN50) compared to night shifts with fixed working hours. The excessive weakening of the parasympathetic component in the passive orthostatic test can be considered as an early marker for ANS maladaptation.

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Energy, Nutrient and Food Intakes of Male Shift Workers Vary According to the Schedule Type but Not the Number of Nights Worked

Nutrients ◽

10.3390/nu12040919 ◽

2020 ◽

Vol 12 (4) ◽

pp. 919

Author(s):

Sophie Bucher Della Torre ◽

Pascal Wild ◽

Victor Dorribo ◽

Brigitta Danuser ◽

Francesca Amati

Keyword(s):

Eating Habits ◽

Night Shift ◽

Food Group ◽

Pooled Analysis ◽

Dietary Intakes ◽

Food Groups ◽

Shift Workers ◽

Increased Risk ◽

Schedule Type ◽

Night Shifts

Shift work is associated with increased risk of chronic diseases due to circadian rhythm disruptions and behavioral changes such as in eating habits. Impact of type of shifts and number of night shifts on energy, nutrient and food intake is as yet unknown. Our goal was to analyze shift workers’ dietary intake, eating behavior and eating structure, with respect to frequency of nights worked in a given week and seven schedule types. Eating habits and dietary intakes of 65 male shift workers were analyzed in three steps based on 365 24-h food records: (1) according to the number of nights, (2) in a pooled analysis according to schedule type, and (3) in search of an interaction of the schedule and the timing of intake. Mean nutrient and food group intake during the study period did not depend on the number of nights worked. Amount and distribution of energy intake as well as quality of food, in terms of nutrient and food groups, differed depending on the type of schedule, split night shifts and recovery day (day after night shift) being the most impacted. Shift workers’ qualitative and quantitative dietary intakes varied between different schedules, indicating the need for tailored preventive interventions.

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Social Jetlag Among Night Workers is Negatively Associated with the Frequency of Moderate or Vigorous Physical Activity and with Energy Expenditure Related to Physical Activity

Journal of Biological Rhythms ◽

10.1177/0748730416682110 ◽

2016 ◽

Vol 32 (1) ◽

pp. 83-93 ◽

Cited By ~ 16

Author(s):

Mariana Silva Alves ◽

Raphael Zardini Andrade ◽

Graciele Cristina Silva ◽

Maria Carliana Mota ◽

Sabrina Gonçalves Resende ◽

...

Keyword(s):

Physical Activity ◽

Energy Expenditure ◽

Short Form ◽

Vigorous Physical Activity ◽

Night Shift ◽

Absolute Difference ◽

Cross Sectional ◽

Shift Workers ◽

Negatively Associated ◽

Social Jetlag

This cross-sectional study analyzed the association between physical activity (PA) and social jetlag (SJL) among shift workers. We evaluated 423 employees, aged between 18 and 60 years, who worked in a poultry-processing company in Brazil. Physical activity levels (PAL) were determined by the short form of the International Physical Activity Questionnaire (IPAQ-SF). SJL was calculated as the absolute difference between the time of mid-sleep on work and free days. The percentage of workers insufficiently active was high on all shifts, with no significant differences between the 3 shifts. The amount of time spent in sedentary behavior on workdays did not differ between shifts. Among night-shift workers, negative associations were observed between SJL and 1) the duration and weekly energy expenditure while walking; 2) the frequency of moderate and vigorous PA; and 3) the total energy expenditure related to PA. Even though PAL did not differ among workers on different shifts, we found a high prevalence of subjects who were insufficiently active or too sedentary among all groups. Also, SJL was negatively associated with PA in night-shift workers. These results suggest that PA should be encouraged among shift workers and that SJL may be an important factor in reducing PA in this cohort.

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Poor Sleep Quality in Nurses Working or Having Worked Night Shifts: A Cross-Sectional Study

Frontiers in Neuroscience ◽

10.3389/fnins.2021.638973 ◽

2021 ◽

Vol 15 ◽

Author(s):

Qiao Huang ◽

Chong Tian ◽

Xian-Tao Zeng

Keyword(s):

Sleep Quality ◽

Clinical Care ◽

Night Shift ◽

Cross Sectional Study ◽

Poor Sleep ◽

Consecutive Night ◽

Sectional Study ◽

Poor Sleep Quality ◽

Cross Sectional ◽

Night Shifts

Night shifts are part of clinical care. It is unclear whether poor sleep quality of nurses working both consecutive night shifts and day shifts after quitting night shifts is common. In this cross-sectional study, Pittsburgh Sleep Quality Index (PSQI) was used to assess sleep quality as study outcome. Univariable and multivariable linear and logistic regressions were performed to compare PSQI score and prevalence of poor sleep quality between 512 nurses currently working consecutive night shifts and 174 nurses having worked night shifts in the past. The prevalence of poor sleep quality was 62.11% in nurses working consecutive night shifts and 55.75% in nurses having worked night shifts before. In multivariable regressions with adjustment for potential confounders, compared with nurses working consecutive night shifts, nurses having worked past night shifts reported decreased PSQI score [mean difference: −0.82 (95% CI: −1.27 to −0.38, p < 0.001)] and lower poor sleep quality [odds ratio (OR): 0.49 (95% CI: 0.29 to 0.80, p = 0.005)]. In nurses working consecutive night shifts, a rising curve that plateaued at the end was observed between years of consecutive night shifts and PSQI score, p = 0.004. To explore the change in PSQI score after quitting night shift, we constructed a hypothetical prospective cohort from the cross-sectional data. Here, 98 pairs of nurses with consecutive and past night shifts were matched for the number of night shift years, religion, marital status, living condition, hypertension, and hyperlipidemia. In each pair, a hypothetical change in PSQI score was calculated between the two types of nurses and hypothetical years after quitting night shifts was obtained from the matched nurse with past night shifts. A U-shaped curve between change in PSQI and years after quitting night shifts was observed, p = 0.007. The rising curve and U-shaped curve together formed an S-shaped curve, which mapped the change in sleep quality. These results based on the hypothetical cohort constructed from cross-sectional data suggested the presence of persistent poor sleep quality in night shift nurses. Also, we support early and continuous sleep hygiene education and reflection for an optimal strategy for when to cease working night shifts with regard to sleep-related problems.

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Designing Light for Night Shift Workers: Application of Nonvisual Lighting Design Principles in an Industrial Production Line

Applied Sciences ◽

10.3390/app112210896 ◽

2021 ◽

Vol 11 (22) ◽

pp. 10896

Author(s):

Johannes Zauner ◽

Herbert Plischke

Keyword(s):

Shift Work ◽

Industrial Production ◽

Night Shift ◽

Stimulus Range ◽

Automation System ◽

Shift Workers ◽

Health And Wellbeing ◽

Rotating Shift Work ◽

Lighting Simulation ◽

Night Shifts

Chronodisruption deteriorates the health and wellbeing of shift workers. Artificial light at night and the lack of light during the day are major contributors to chronodisruption and need to be optimized in shift work scenarios. Here, we present one solution for a lighting and automation system in an industrial production workplace. The setting is a rapidly rotating shift work environment with morning, evening, and night shifts. We describe a procedure to specify the new lighting through a software-agnostic nonvisual lighting simulation for artificial and daylighting scenarios. Through this process, a new luminaire is created, called Drosa, that allows for a large melanopic stimulus range between 412 and 73 lx melanopic equivalent daylight (D65) illuminance vertically at eye level, while maintaining a neutral white illuminance at task level between 1250 and 900 lx, respectively. This is possible through a combination of glare-free spotlights with adjustable areal wing lights. An individually programmed automation system controls the light dosage and timing during the day and night. The work is relevant for other shift work scenarios, where the presented example and the discussed rationale behind the automation might provide insights. The work is further relevant for other lighting scenarios beyond industrial shift work, as the nonvisual lighting simulation process can be adapted to any context.

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Diurnal rhythms of cortisol and melatonin in night eating and non-night eating male police officers

European Journal of Public Health ◽

10.1093/eurpub/ckz186.330 ◽

2019 ◽

Vol 29 (Supplement_4) ◽

Author(s):

J K Sørensen ◽

M A Jensen ◽

ÅM Hansen ◽

R Rugulies ◽

A H Garde

Keyword(s):

Diurnal Rhythm ◽

Police Officers ◽

Night Shift ◽

Eating Behaviour ◽

Cortisol Concentration ◽

Diurnal Rhythms ◽

Consecutive Night ◽

Night Eating ◽

Main Meal ◽

Night Shifts

Abstract Background Working during the night has in previous studies been associated with behavioural changes and diseases. Disturbance between behavioural and biological circadian rhythms have been suggested as a possible mechanism linking night work with cardiovascular diseases and pre-diabetic changes. The aim of this study was to investigate if night eating during two, four and seven consecutive night shifts is associated with differences in the diurnal rhythms of cortisol and melatonin in male police officers in Denmark. Methods We conducted an experimental study among 37 male police officers in Denmark who all collected data on the last night shift in three different work schedules with two, four and seven consecutive night shifts, respectively. Night eating was self-reported and defined as eating at least one main meal between midnight and early morning. Differences in the diurnal rhythms of concentrations of cortisol and melatonin in saliva were tested by phase changes and amplitude differences. Results Sixteen (43.2%) police officers ate a main meal during the last night shift in all three work schedules. The timing of the lowest cortisol concentration was on average delayed with 2:10 hours (95% CI 0:24-3:56 hours) and the level of the lowest cortisol concentration was on average supressed with 66% (95% CI 47-94%) for night eaters compared to non-night eaters. There was no association with number of consecutive night shifts. The phase and amplitude of melatonin were not statistically significantly different between night eaters and non-night eaters. Conclusions Night eating behaviour is associated with differences in the diurnal rhythm of cortisol in Danish male police officers working during the night. The difference in cortisol rhythm between night eaters and non-night eaters on night shifts is not affected by the number of consecutive night shifts. Key messages Night eating behaviour is associated with differences in the diurnal rhythm of cortisol. Future studies should focus on potential health outcomes of night eating behaviour among night workers.

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