Napping on the night shift and its impact on blood pressure and heart rate variability among emergency medical services workers: study protocol for a randomized crossover trial

Abstract Background There is an emerging body of evidence that links exposure to shift work to cardiovascular disease (CVD). The risk of coronary events, such as myocardial infarction, is greater among night shift workers compared to day workers. There is reason to believe that repeated exposure to shift work, especially night shift work, creates alterations in normal circadian patterns of blood pressure (BP) and heart rate variability (HRV) and that these alterations contribute to increased risk of CVD. Recent data suggest that allowing shift workers to nap during night shifts may help to normalize BP and HRV patterns and, over time, reduce the risk of CVD. The risk of CVD related to shift work is elevated for emergency medical services (EMS) shift workers due in part to long-duration shifts, frequent use of night shifts, and a high prevalence of multiple jobs. Methods We will use a randomized crossover trial study design with three study conditions. The targeted population is comprised of EMS clinician shift workers, and our goal enrollment is 35 total participants with an estimated 10 of the 35 enrolled not completing the study protocol or classified as lost to attrition. All three conditions will involve continuous monitoring over 72 h and will begin with a 36-h at-home period, followed by 24 total hours in the lab (including a 12-h simulated night shift), ending with 12 h at home. The key difference between the three conditions is the intra-shift nap. Condition 1 will involve a simulated 12-h night shift with total sleep deprivation. Condition 2 will involve a simulated 12-h night shift and a 30-min nap opportunity. Condition 3 will involve a simulated 12-h night shift with a 2-h nap opportunity. Our primary outcomes of interest include blunted BP dipping and reduced HRV as measured by the standard deviation of the inter-beat intervals of normal sinus beats. Non-dipping status will be defined as sleep hours BP dip of less than 10%. Discussion Our study will address two indicators of cardiovascular health and determine if shorter or longer duration naps during night shifts have a clinically meaningful impact. Trial registration ClinicalTrials.gov NCT04469803. Registered on 9 July 2020

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Elevated Blood Pressure, Decreased Heart Rate Variability and Incomplete Blood Pressure Recovery after a 12‐hour Night Shift Work

Journal of Occupational Health ◽

10.1539/joh.l7056 ◽

2008 ◽

Vol 50 (5) ◽

pp. 380-386 ◽

Cited By ~ 49

Author(s):

Ta‐Chen Su ◽

Lian‐Yu Lin ◽

Dean Baker ◽

Peter L. Schnall ◽

Ming‐Fong Chen ◽

...

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

Heart Rate Variability ◽

Shift Work ◽

Night Shift ◽

Pressure Recovery ◽

Elevated Blood Pressure ◽

Elevated Blood ◽

Night Shift Work

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Abstract 14384: Light Therapy Improves Circadian Blood Pressure Control and Glucose Homeostasis in Rotating Night Shift Workers via Mechanisms Independent of Melatonin

Circulation ◽

10.1161/circ.142.suppl_3.14384 ◽

2020 ◽

Vol 142 (Suppl_3) ◽

Author(s):

Juliane Hannemann ◽

Anika Laing ◽

Benita Middleton ◽

Jonathan Cridland ◽

Bart Staels ◽

...

Keyword(s):

Blood Pressure ◽

Circadian Rhythms ◽

Glucose Tolerance ◽

Shift Work ◽

Therapy Group ◽

Night Shift ◽

Light Therapy ◽

Pressure Control ◽

Shift Workers ◽

Night Shifts

Introduction: Night shift work is associated with high rates of hypertension, heart disease, and metabolic syndrome. These cardiometabolic diseases have been linked to the disruption of circadian rhythms in night shift workers. Rotating night shift work is increasingly common in the working population worldwide. Hypothesis: We hypothesized that light therapy might help to normalize disrupted circadian rhythms and stabilize diurnal control of blood pressure and glucose tolerance in rotating night shift workers. Methods: We randomized 24 rotating night shift workers (mean age, 36±13 years, 7 males) who had spent a median of 6 years on rotating night shifts with a median of 6 night shifts/month to 12 weeks of light therapy (light during first half of each night shift and in the morning of off-work days) or no intervention and compared them with 12 daytime workers (37±11 years, 6 males). We measured oral glucose tolerance (OGTT), 24h blood pressure and arterial stiffness, and the circadian profiles of melatonin, cortisol, metanephrine and normetanephrine at baseline, after 12 weeks of intervention, and 12 weeks after the end of intervention. Results: At baseline, fewer night shift workers showed dipper status of blood pressure as compared to daytime workers (21% vs. 55%; p<0.001). After 12 weeks of light therapy, there was a highly significant increase in the proportion of dippers (to 42%; p<0.0001). We also observed a significant decrease in serum glucose during OGTT in the light therapy group (-22%; p<0.05), with no change in serum insulin. Whilst circadian profiles of melatonin and cortisol were unchanged, there was a significant reduction in nighttime plasma metanephrine and normetanephrine levels in the light therapy group (p<0.01). Conclusions: Chronotherapeutic light therapy significantly improves diurnal blood pressure control and glucose tolerance in rotating night shift workers. This effect is unrelated to mechanisms traditionally linked to the circadian clock like melatonin and cortisol, but it is paralleled by reduced catecholamine levels. Our data suggest that chronotherapeutic light therapy may improve the adjustment to atypical working hours in rotating night shift workers, thereby reducing stress and improving cardiometabolic function.

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Ambulatory blood pressure monitoring among emergency medical services night shift workers

Occupational and Environmental Medicine ◽

10.1136/oemed-2020-106459 ◽

2020 ◽

Vol 78 (1) ◽

pp. 29-35

Author(s):

P Daniel Patterson ◽

Kristina A Mountz ◽

Michael G Agostinelli ◽

Matthew D Weaver ◽

Yi-Chuan Yu ◽

...

Keyword(s):

Blood Pressure ◽

Emergency Medical Services ◽

Shift Work ◽

Ambulatory Blood Pressure ◽

Blood Pressure Monitoring ◽

Night Shift ◽

Pressure Monitoring ◽

Night Time ◽

Shift Workers ◽

Night Shift Work

ObjectivesHigher 24-hour blood pressure (BP) and blunted BP dipping during sleep and night-time hours are associated with adverse health outcomes. Night shift work may affect 24-hour BP and dipping patterns, but empirical data in emergency medical services (EMS) clinician shift workers are sparse. We implemented ambulatory blood pressure monitoring (ABPM) in EMS workers to characterise BP during night shift work versus a non-workday, and sleep versus wake.MethodsParticipants worked night shifts. Hourly ABPM and wrist actigraphy (to measure sleep) were collected during two 24-hour periods, one scheduled night shift and one non-workday. Blunted BP dipping was defined as a BP decrease of <10%.ResultsOf 56 participants, 53 (53.6% female, mean age 26.5 (SD 7.5) years) completed the study. During daytime sleep on a workday, 49.1% of participants had blunted systolic BP (SBP) or diastolic BP (DBP) dipping. During night-time sleep on a non-workday, 25% had blunted SBP dipping and 3.9% blunted DBP dipping. Blunted SBP or DBP dipping occurred among all participants who did not nap during the night shift or who napped <60 min. Blunted SBP dipping occurred in only 14.3% of participants who napped 60–120 min.ConclusionsDuring night shift work, the BP dipping of EMS shift workers is blunted; however, most who nap for 60 min or longer experience a healthy dip in BP. The potential health consequences of these observations in EMS clinicians warrant further study.

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Napping on the Night Shift and Impact on Blood Pressure and HRV among EMS Workers

10.14293/s2199-1006.1.sor-.ppirrng.v1 ◽

2021 ◽

Author(s):

Ektha Parchuri ◽

James Paule

Keyword(s):

Blood Pressure ◽

Shift Work ◽

Night Shift ◽

Shift Workers ◽

Frequent Use ◽

Long Duration ◽

High Prevalence ◽

Circadian Patterns ◽

Night Shifts ◽

Over Time

Recent evidence linking exposure toshift work to cardiovascular disease (CVD) as well as incidence of myocardial infarction seems to be greater among night shift workers compared to day workers. Repeated exposure tonight shift work causes disruptions in normal circadian patterns of blood pressure (BP) and heart rate variability (HRV), which cause anincreased risk of CVD. Recent data suggest that allowing shift workers to nap during night shifts may help to normalize BP and HRV patterns and, over time, reduce the risk of CVD. The risk of CVD related to shift work is elevated for emergency medical services (EMS) shift workers due in part to long-duration shifts, frequent use of night shifts, and a high prevalence of multiple jobs. Therefore, the effect of SBP and HRV in EMS night shift workers is analyzed through stimulated night work and it's effect on CVD is characterized.

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Measuring the effects of night-shift work on cardiac autonomic modulation: an appraisal of heart rate variability metrics

International Journal of Occupational Medicine and Environmental Health ◽

10.13075/ijomeh.1896.01560 ◽

2020 ◽

Vol 33 (4) ◽

pp. 409-425 ◽

Cited By ~ 1

Author(s):

Anne Fink

Keyword(s):

Heart Rate ◽

Heart Rate Variability ◽

Shift Work ◽

Night Shift ◽

Autonomic Modulation ◽

Night Shift Work ◽

Cardiac Autonomic Modulation

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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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Impact of shift work on blood pressure among emergency medical services clinicians and related shift workers: A systematic review and meta-analysis

Sleep Health ◽

10.1016/j.sleh.2020.03.006 ◽

2020 ◽

Vol 6 (3) ◽

pp. 387-398 ◽

Cited By ~ 3

Author(s):

P. Daniel Patterson ◽

Kristina A. Mountz ◽

Caitlin T. Budd ◽

Jenna L. Bubb ◽

Austin U. Hsin ◽

...

Keyword(s):

Systematic Review ◽

Blood Pressure ◽

Emergency Medical Services ◽

Shift Work ◽

Meta Analysis ◽

Medical Services ◽

Shift Workers ◽

Emergency Medical

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Diurnal and Seasonal Variations in Industrial Fatigue of Shift Workers

Proceedings of the Human Factors Society Annual Meeting ◽

10.1177/154193127602002203 ◽

1976 ◽

Vol 20 (22) ◽

pp. 515-518

Author(s):

Andrzej Ogiński ◽

Lucyna Koźlakowska-Swigoń ◽

Janusz Pokorski

Keyword(s):

Heart Rate ◽

Shift Work ◽

Pulse Rate ◽

Seasonal Variations ◽

Shift Workers ◽

Seasonal Factor ◽

Analysis Of Results ◽

Fatigue Estimation ◽

Continuous Work ◽

Night Shifts

The interview was carried out with 1664 steelworkers in the aim of obtaining their opinion on subjective fatigue accompanying the work on morning, afternoon and night shifts. Warm and cold seasons of the year were treated separately. Continuous work observations and telemetric heart rate registration were conducted at some workplaces. Analysis of results exhibited a great differentiation of fatigue estimation on particular shifts. Influence of the seasonal factor was found to be very important both in the reported feeling of fatigue as in changes of the pulse rate. Conclusions concern the ergonomic approach to fatigue problems in shift work.

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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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