The effect of blue-enriched white light on cognitive performances and sleepiness of night-shift workers: A field study

Abstract Introduction Many shift workers have an inability to sleep during the daytime following a night shift not due to insomnia or lack of sleep pressure, but because a circadian signal promoting wakefulness is hampering their ability to maintain sleep. We have previously hypothesized that the neuropeptide hypocretin-1 is, in part, responsible for the physiologic expression of this circadian wake signal. As such, it was our intent to determine whether a pharmacologic blockade of hypocretin would enable shift workers to obtain more daytime sleep. Methods Nineteen shift workers took part in a placebo-controlled, double-blind field study of suvorexant. Following two weeks of baseline, participants received 10 mg suvorexant/placebo for one week and were titrated upward to 20 mg suvorexant/placebo for an additional two weeks. Subjective (diaries) and objective (actigraphy) sleep were monitored throughout. No restrictions were placed on participants’ schedules. Results Both subjective and objective measures of total sleep time significantly improved in the active vs. the placebo condition, increasing by 2.08 ± 0.47 hours (diary) or 1.04 ± 0.53 hours (actigraphy) by the end of the 10 mg condition, and increasing by 2.97 ± 0.56 hours (diary) or 2.16 ± 0.75 hours (actigraphy) by the end of the 20 mg condition. Physician ratings of change in the severity of symptoms similarly improved in the active group. There were no adverse events reported in the active condition. Conclusion Robust changes in total sleep time were observed after administration of suvorexant, a dual-hypocretin antagonist, prior to daytime sleep in a field study of shift workers. The very large changes in total sleep time, coupled with the permissive nature of the therapeutic mechanism (i.e., suppressing wake rather than inducing sleep) indicate that this could be a viable and important therapy for shift workers. Support Merck Sharpe and Dohme investigator-initiated study #53236

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Alterations in Rev-ERBα/BMAL1 ratio and glycated hemoglobin in rotating shift workers: the EuRhythDia study

Acta Diabetologica ◽

10.1007/s00592-021-01676-z ◽

2021 ◽

Cited By ~ 1

Author(s):

Stefano Rizza ◽

Alessio Luzi ◽

Maria Mavilio ◽

Marta Ballanti ◽

Arianna Massimi ◽

...

Keyword(s):

Mononuclear Cells ◽

Glycated Hemoglobin ◽

Night Shift ◽

Multivariate Regression Analysis ◽

Peripheral Blood Mononuclear ◽

Cross Sectional ◽

Shift Workers ◽

Metabolic Defects ◽

Clock Gene Expression ◽

Cell Counts

Abstract Objective To detect premature gluco-metabolic defects among night shift workers with disturbances in circadian rhythms. Design and methods We performed a hypothesis-generating, cross-sectional analysis of anthropometric, metabolic, lipid, and inflammation parameters, comparing active (a-NSW, n = 111) and former (f-NSW, n = 98) rotating night shift workers with diurnal workers (controls, n = 69). All participants were hospital nurses. We also evaluated the Pittsburgh Sleep Quality Index (PSQI) and assessed expression of transcription factors REV-ERBα and BMAL1 in peripheral blood mononuclear cells (PBMCs), as indicators of the molecular clock. Results Both a-NSW and f-NSW participants had significantly higher glycated hemoglobin (HbA1c) and white blood cell counts (WBC) (p < 0.001 for both), PSQI global score (p = 0.001) and diastolic blood pressure levels (p = 0.024) compared with controls. Expression of REV-ERBα/BMAL1 RNA in PBMC was significantly higher in a-NSW (p = 0.05) than in f-NSW or control participants. Multivariate regression analysis showed that working status and PSQI were independent determinants of higher HbA1c levels (p < 0.001). Conclusions We demonstrated that young, healthy night shift workers show subclinical abnormalities in HbA1c and changes in peripheral clock gene expression.

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Effects of work organization on the occurrence and resolution of sleep disturbances among night shift workers: a longitudinal observational study

Scientific Reports ◽

10.1038/s41598-021-85017-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Seungho Lee ◽

Jae Bum Park ◽

Kyung-Jong Lee ◽

Seunghon Ham ◽

Inchul Jeong

Keyword(s):

Work Experience ◽

Sleep Disturbances ◽

Sleep Problems ◽

Night Shift ◽

Work Organization ◽

Severity Index ◽

Estimating Equation ◽

Health Examination ◽

Related Factors ◽

Shift Workers

AbstractThis study aimed to investigate the association between work organization and the trajectories of insomnia patterns among night shift workers in a hospital. The health examination data of hospital workers, recorded from January 2014 to December 2018, were collected; 6765 records of 2615 night shift workers were included. Insomnia was defined as a score of ≥ 15 on the Insomnia Severity Index (ISI). Participants were categorized into five groups according to insomnia patterns derived from the analysis of their ISI scores. Work organization and socio-demographic characteristics were also investigated. Generalized estimating equation models and linear mixed models were constructed to analyze the longitudinal data. Of the total participants, 53.0% reported insomnia at least once during the follow-up period. The lack of nap opportunities and work-time control was associated with the occurrence of insomnia, whereas more than 5 years of shift work experience was related to the resolution of insomnia. All work-related factors were significantly related to insomnia risk; however, the effects were not significant in the sustained insomnia group. Although sleep problems are inevitable in night shift workers, well-designed work schedules and better work organization can help reduce the occurrence of insomnia among them.

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Chronotype-specific Sleep in Two Versus Four Consecutive Shifts

Journal of Biological Rhythms ◽

10.1177/07487304211006073 ◽

2021 ◽

pp. 074873042110060

Author(s):

Dorothee Fischer ◽

Till Roenneberg ◽

Céline Vetter

Keyword(s):

Night Shift ◽

Sleep Diary ◽

Sequence Length ◽

Consecutive Night ◽

Shift Workers ◽

Subject Field ◽

Sleep Diaries ◽

Social Jetlag ◽

Sleep Debt ◽

Night 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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Light therapy improves diurnal blood pressure control in night shift workers via reduction of catecholamines

Journal of Hypertension ◽

10.1097/hjh.0000000000002848 ◽

2021 ◽

Vol Publish Ahead of Print ◽

Author(s):

Juliane Hannemann ◽

Anika Laing ◽

Benita Middleton ◽

Jonathan Cridland ◽

Bart Staels ◽

...

Keyword(s):

Blood Pressure ◽

Blood Pressure Control ◽

Night Shift ◽

Light Therapy ◽

Pressure Control ◽

Shift Workers

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Excessive mechanical strain accelerates intervertebral disc degeneration by disrupting intrinsic circadian rhythm

Experimental & Molecular Medicine ◽

10.1038/s12276-021-00716-6 ◽

2021 ◽

Author(s):

Sheng-Long Ding ◽

Tai-Wei Zhang ◽

Qi-Chen Zhang ◽

Wang Ding ◽

Ze-Fang Li ◽

...

Keyword(s):

Circadian Rhythm ◽

Intervertebral Disc ◽

Mechanical Loading ◽

Disc Degeneration ◽

Intervertebral Disc Degeneration ◽

Night Shift ◽

Mechanical Strain ◽

Inhibitory Effect ◽

Shift Workers ◽

Normal Environment

AbstractNight shift workers with disordered rhythmic mechanical loading are more prone to intervertebral disc degeneration (IDD). Our results showed that circadian rhythm (CR) was dampened in degenerated and aged NP cells. Long-term environmental CR disruption promoted IDD in rats. Excessive mechanical strain disrupted the CR and inhibited the expression of core clock proteins. The inhibitory effect of mechanical loading on the expression of extracellular matrix genes could be reversed by BMAL1 overexpression in NP cells. The Rho/ROCK pathway was demonstrated to mediate the effect of mechanical stimulation on CR. Prolonged mechanical loading for 12 months affected intrinsic CR genes and induced IDD in a model of upright posture in a normal environment. Unexpectedly, mechanical loading further accelerated the IDD in an Light-Dark (LD) cycle-disrupted environment. These results indicated that intrinsic CR disruption might be a mechanism involved in overloading-induced IDD and a potential drug target for night shift workers.

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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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