Effect of Short versus Long Duration Naps on Blood Pressure during Simulated Night Shift Work: A Randomized Crossover Trial.

OBJECTIVE: Blunting of the sleep-related dip in blood pressure (BP) has been linked to numerous cardiovascular outcomes including myocardial infarction. Blunting of BP dipping occurs during night shift work and previous research suggest that a 60-min or longer on-shift nap is needed to restore normal/healthy BP dipping. We sought to determine the effect of different durations of napping on BP during and following simulated night shifts. We hypothesized that the greatest benefit in terms of restoration of normal BP dipping during night shift work would be observed during a longer duration nap versus a shorter nap opportunity. METHODS: We used a randomized crossover laboratory-based study design. Participants consented to complete three separate 72-hr conditions that included a 12-hr simulated night shift. Nap conditions included a 30-min and 2-hr nap compared to a no-nap condition. Ambulatory BP monitoring was assessed hourly and every 10-30 mins during in-lab naps. Blunted BP dipping during in-lab naps was the primary outcome. Goal enrollment of 25 (35 with attrition) provided 80% power to detect a mean difference of 5 mmHg in BP between nap conditions. RESULTS: Of the 58 screened, 28 were consented, and 26 completed all three 72-hr conditions. More than half (53.6%) were female. Mean age was 24.4 years (SD7.2). Most (85.7%) were certified as emergency medical technicians or paramedics. The mean percentage dip in systolic BP (SBP) and diastolic BP (DBP) did not differ between the 30-min and 2-hr nap conditions (p > 0.05), yet a greater proportion of participants experienced a 10-20% dip in SBP or DBP during the 2-hr nap versus the 30-min nap (p < 0.05). For every additional minute of total sleep during the 30-min nap, the percentage of SBP dip improved by 0.60%, and the percentage of DBP dip improved by 0.68% (p < 0.05). These improvements approximate to a 6% per minute relative advancement toward normal/healthy BP dipping. CONCLUSIONS: Restoration of a normal/healthy dip in BP is achievable during short and long duration nap opportunities during simulated night shift work. Our findings support the hypothesis that BP dipping is more common during longer 2-hr versus shorter 30-min naps. TRIAL REGISTRATION: ClinicalTrials.gov, NCT04469803. Registered on 9 July 2020.

Masking by health care and public safety workers in non-patient care areas to mitigate SARS-CoV-2 infection: A systematic review.

Objectives: Wearing a mask is an important method for reducing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission in health care and public safety settings. We assess the evidence regarding masking in the workplace during the initial months of the COVID-19 pandemic (PROSPERO CRD4202432097). Methods: We performed a systematic review of published literature from 4 databases and evaluated the quality of evidence with the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) framework. We searched for observational and experimental research involving public safety and health care workers. We included articles evaluating the use of masks, versus no mask, on the outcome of SARS-CoV-2 infection. Results: Our search yielded 15,013 records, of which 9 studies were included. Most studies (n = 8; 88.9%) involved infections or outbreaks among health care workers. The majority (88.9%) used in-depth interviews of cases and non-cases to obtain self-reported use of masks during periods of exposure. One of 9 studies quantitatively assessed differences in SARS-CoV-2 infection based on use of masks in non-patient care settings. Use of observational study designs, small sample sizes, inadequate control for confounding, and inadequate measurement of exposure and non-exposure periods with infected coworkers contributed to the quality of evidence being judged as very low. Conclusions: The available evidence from the initial months of the pandemic suggests that the use of masks in congregate, non-patient care settings, such as breakrooms, helps to reduce risk of SARS-CoV-2 virus transmission. However, this evidence is limited and is of very low quality. Prospective studies incorporating active observation measures are warranted.

Does the evidence support brief (≤30-mins), moderate (31-60-mins), or long duration naps (61+ mins) on the night shift? A systematic review.

We performed a systematic review of four databases to determine if the evidence supports a short or long duration nap during night shifts to mitigate fatigue, and/or improve health, safety, or performance for emergency services and public safety personnel (PROSPERO CRD42020156780). We focused on experimental research and evaluated the quality of evidence with the grading of recommendations, assessment, development, and evaluation (GRADE) framework. We used the Cochrane Collaboration's risk of bias tool to assess bias and reported findings using the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement. Our search yielded n = 10,345 records and n = 44 were reviewed in full-text. Inter-rater agreement during screening was substantial (Kappa = 0.66). We retained n = 11 publications, reporting on n = 7 experimental studies with a cumulative sample size of n = 140. We identified wide variation in study design, napping interventions (i.e., timing, placement, and duration), and outcomes. We identified mixed findings comparing brief, moderate, and long duration naps on outcomes of interest. All seven studies presented serious risk of bias and the quality of evidence was rated as low. Based on the best available evidence, decisions regarding nap duration during night shift work should be based on time (post-nap) and outcome.