Night Shift Work, On-shift Napping, and Endothelial Function: A Pilot Study

Study Overview
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Brief Summary
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Cardiovascular disease (CVD) and CVD risk factors such as high blood pressure (BP) are disproportionately higher among night shift workers, including those who work in public safety and healthcare. The purpose of this pilot study is to assess feasibility of collecting data germane to key indicators of cardiovascular health (i.e., ambulatory blood pressure) repeatedly during a simulated night shift protocol. The primary outcome measure will be the number of participants for which at least 70% of required ambulatory BP measures were collected. A result of at least 10 participants/subjects will be considered feasible.

Detailed Description
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Cardiovascular disease (CVD) and CVD risk factors such as high blood pressure (BP) are disproportionately higher among night shift workers, including those who work in public safety and healthcare. Risk of CVD events such as myocardial infarction and stroke are higher among shift workers than non-shift workers. Risk of atrial fibrillation is 1.22 times greater (95%CI 1.02, 1.45) among individuals that work 3-to-8 night shifts per month versus non-shift workers. A comprehensive explanation for why shift workers, especially night shift workers, are at greater risk of CVD is not yet available. However, some research suggests that night shift workers experience repeated exposure to sleep deprivation, which impacts normal patterns in BP and endothelial function. Endothelial dysfunction and disruption of normal BP patterns are independently linked to numerous indicators of CVD, including cardiac-related mortality. The purpose of this pilot study is to assess feasibility of collecting data germane to key indicators of cardiovascular health (i.e., ambulatory blood pressure) repeatedly during a simulated night shift protocol. Investigators propose a laboratory-based pilot study whereby participants (volunteers) complete two conditions. Condition one will include a 12-hour simulated night shift in our lab with no napping. Condition two will involve a 12-hour simulated night shift in our lab with a 45 minute nap at 0200 hours. Participants will be asked to wear monitoring devices for approximately 48 total hours with the last 12 hours of monitoring (from 1900 to 0700) to be in our lab. Aim 1: Assess the feasibility of collecting ambulatory BP measures (ABPM) and indicators of endothelial function at multiple time points prior to, during, and after simulated night shift work. The primary outcome measure will be the number of participants for which at least 70% of required ambulatory BP measures were collected. A result of at least 10 participants/subjects will be considered feasible. Aim 2: Characterize the impact of simulated night shift work and on-shift napping on BP dipping and endothelial function. Secondary endpoints include quantifying descriptive statistics (e.g., means and standard deviations) for BP dipping and endothelial function.

Official Title
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Night Shift Work, On-shift Napping, and Endothelial Function: A Pilot Study

Conditions
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Blood Pressure, Endothelial Dysfunction

Intervention / Treatment
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* Behavioral: Brief on-shift nap


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: All participants will be working aged adults (18 years of age or older). Investigators are interested in enrolling public safety workers and healthcare workers given how often this group works night shifts. Criteria that participants will need to address: 18 years of age or older; Currently licensed or certified as an EMS clinician, other public safety shift worker, or other type of healthcare clinicians and actively working in Western Pennsylvania as an EMT, Paramedic, Flight Nurse/Paramedic, other EMS clinician, firefighter, or other type of healthcare clinician (e.g., nurse, physician, physician assistants, patient care technician, or other healthcare clinician); a 'no' answer to #2 above is not a criterion for exclusion. Exclusion Criteria: Having ever been diagnosed with the following: hypertension, cardiovascular disease, myocardial infarction, stroke/TIA, chronic kidney disease, liver disease, adrenal disease, thyroid disease, rheumatologic disease, hematologic disease, cancer of any type, dementia/memory loss, organ transplantation; major sleep problem; heavy alcohol use; sleep apnea or other diagnosis that is related to problems with breathing or the airway; Current pregnancy; Insomnia is NOT a criterion for exclusion.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 100 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: Randomized crossover study design
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: No-nap, then brief 45-minute nap<br>Participants will be monitored for a total of 48 hours, including a 12-hour simulated night shift. At baseline (consent), participants are randomized to a crossover study design with two study arms (no nap, brief 45-minute nap). In this sequence, participants will perform the 12-hour simulated night shift with no nap first, undergo a minimum of 1-week washout, then return complete the 48-hour protocol again with the brief 45-minute nap. | Behavioral: Brief on-shift nap<br>* The brief nap opportunity will allow for a 45-minute nap between the hours of 0200 and 0300 during the in-lab 12-hour simulated night shift.<br>|
| Experimental: The brief 45-minute nap, then no-nap<br>Participants will be monitored for a total of 48 hours, including a 12-hour simulated night shift. At baseline (consent), participants are randomized to a crossover study design with two study arms (no nap, brief 45-minute nap). In this sequence, participants will perform the 12-hour simulated night shift with the brief 45-minute nap, undergo a 1-week minimum washout, then return to complete the 48-hour protocol again with the no-nap | Behavioral: Brief on-shift nap<br>* The brief nap opportunity will allow for a 45-minute nap between the hours of 0200 and 0300 during the in-lab 12-hour simulated night shift.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of Participants for which at least 70% of required Ambulatory BP readings were collected | A result of at least 10 participants will be considered feasible | 48 continuous hours for each arm/condition | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Average blood pressure while awake during simulated night shift | The mean and standard deviation of blood pressure measurements taken while participant is awake during the 12-hour simulated night shift | 12 continuous hours for each arm/condition | 
| Average blood pressure while napping during simulated night shift | The mean and standard deviation of blood pressure measurements taken while participant is napping (sleeping) during the 12-hour simulated night shift that includes the 45-minute nap condition. | 45 minutes | 
| Average Reactive Hyperemia Index (RHI) at baseline | The mean and standard deviation RHI score for the endothelial dysfunction measurement assessed at baseline | 20-30 minutes for each arm/condition | 
| Average Reactive Hyperemia Index (RHI) after simulated night shift | The mean and standard deviation RHI score for the endothelial dysfunction measurement assessed after the 12-hour simulated night shift | 20-30 minutes for each arm/condition | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Ambulatory Blood Pressure, Endothelial Dysfunction