Effects of Two 15-min Naps on the Subjective Sleepiness, Fatigue and Heart Rate Variability of Night Shift Nurses

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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Evaluation of Offshore Shiftwork using Heart Rate Variability

Proceedings of the Human Factors and Ergonomics Society Annual Meeting ◽

10.1177/1541931213601742 ◽

2017 ◽

Vol 61 (1) ◽

pp. 1036-1039 ◽

Cited By ~ 3

Author(s):

Ashley E. Shortz ◽

Madeline Franke ◽

E. Simay Kilic ◽

S. Camille Peres ◽

Ranjana K. Mehta

Keyword(s):

Heart Rate ◽

Heart Rate Variability ◽

Oil And Gas ◽

Night Shift ◽

Physical Workload ◽

Shift Workers ◽

High Fatality Rate ◽

Main Effect ◽

Physiological Profiles ◽

Physiological Sensors

The high fatality rate in oil and gas extraction (OGE) is a growing concern within the industry. OGE workers are exposed to long work hours, intense mental and physical workload, coupled with changing shift patterns, which can lead to elevated fatigue levels. The aim of this study was to explore the effect of shiftwork on heart rate variability indicators of workload and fatigue using wearable monitors in offshore operations. Ten male operators (age: 31.3 (6.1) years; stature: 1.72 (0.1) m; weight: 85.24 (9.8) kg) were monitored throughout their daily shifts for six days on an offshore drillship using physiological sensors. Heart rate variability (HRV) was measured in the frequency (ratio of low to high frequency; LF/HF) and temporal (root mean square of successive differences; RMSSD) domains. Six of the ten operators underwent swing shifts in the middle of the data collection period. There was a main effect of shift time on HRV parameters (i.e., operators on night shift were in a more fatigued state), and a main effect of swing shift on LF/HF (i.e., when swing shift occurred, those operators were more fatigued). Findings suggest that physiological profiles differ based on shift time and swing shifts, and that swing shifts for night shift workers adversely affect heart rate variability responses.

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