Impact of Intra-Shift Napping on EMS Cardiovascular Health

NCT04469803 | Completed

• 1 other identifier: STUDY19120222
• Study Type: interventional
• Target: 28
• Locations: 1 country
• Sites: 1

Brief Summary

Cardiovascular disease (CVD) exerts a significant health burden among shift workers, including police, firefighters, and emergency medical services (EMS). The unique occupational demands inherent to these professions--sleep loss, circadian misalignment, high stress, and sustained hyper-vigilance--confer increased risk for both on and off-duty cardiovascular events. Mitigating cardiovascular risks in these professions requires that we first identify robust markers and potential mechanisms of risk. Previous work suggest shift work has a negative impact on blood pressure (BP) and heart rate variability (HRV). Blunted BP dipping at night and during sleep, and reduced HRV are powerful markers of increased CVD risk. Both are linked to preclinical indicators of cardiac damage, such as presence of coronary artery calcium, left atrial enlargement, and cardiovascular-related mortality. This study will use an experimental crossover study design with three intervention conditions to test the impact of a 30 minute brief nap and a 2-hour longer nap versus no nap on BP and HRV. Outcomes of interest include blunted dipping of BP during nighttime hours and during sleep and HRV.

Conditions

Blood Pressure; Heart Rate Variability

Outcome Measures

Primary Outcomes (3)

• Number of participants with blunted dipping of blood pressure via the sleep based method

  Blood pressure is created by the heart muscle contractions and is measured using two numbers: The Systolic Blood Pressure (SBP) and the Diastolic Blood Pressure (DBP). Normal patterns in BP include elevations in SBP and DBP during the daylight and waking hours followed by a drop (dip) during nighttime hours and during sleep. A dip of 10% to 20% during nighttime or sleep is considered normal, whereas a dip \<10% is defined as blunted BP dipping. Blunted BP dipping will be quantified as: \[(mean BP during waking hours - mean BP during sleep) / mean BP during waking hours\] X 100 - the "sleep-based method."

  Blood pressure will be monitored with automated devices at 1-hour intervals over 72 total hours

• Number of participants with blunted dipping of blood pressure via the wide fixed time method

  Blood pressure is created by the heart muscle contractions and is measured using two numbers: The Systolic Blood Pressure (SBP) and the Diastolic Blood Pressure (DBP). Normal patterns in BP include elevations in SBP and DBP during the daylight and waking hours followed by a drop (dip) during nighttime hours and during sleep. A dip of 10% to 20% during nighttime or sleep is considered normal, whereas a dip \<10% is defined as blunted BP dipping. Blunted BP dipping during nighttime hours (2300 to 0659 hours) vs. daytime hours (0700 to 2259 hours) will be quantified as: \[(mean daytime BP - mean nighttime BP) / mean daytime hours BP\] X 100 - the "wide-fixed time method."

  Blood pressure will be monitored with automated devices at 1-hour intervals over 72 total hours

• The number of participants with unhealthy Heart Rate Variability (HRV) measured via the standard deviation of the inter-beat intervals of normal sinus beats (SDNN)

  A healthy heart oscillates and beat-to-beat fluctuations are variable. Greater variability in heart rate is associated with better health, the capacity to respond and cope, and better performance. The Heart Rate Variability (HRV) measure standard deviation of the inter-beat intervals of normal sinus beats (SDNN) is considered standard and is calculated in milliseconds (ms) over short-term (e.g., 60 seconds) and long-term intervals (24 hours). Values of SDNN \<50ms are considered unhealthy for medical risk stratification.

  HRV will be monitored with a holter monitor continuously over 72 total hours

Study Arms (6)

No nap, brief nap, then longer nap

EXPERIMENTAL

Participants will be monitored for 72 total hours, including a 12-hour simulated night shift. At baseline (consent), participants randomized to crossover study design with three study arms (No nap, brief nap, longer nap). In this sequence, participants will perform the 12-hour night shift with no nap first, undergo a 1-week minimum washout, then complete the protocol again with a brief nap, then undergo a minimum 1-week washout, then return to complete the protocol again with a longer nap opportunity.

Behavioral: Intra-Shift Napping

No nap, longer nap, then brief nap

EXPERIMENTAL

Participants will be monitored for 72 total hours, including a 12-hour simulated night shift. At baseline (consent), participants randomized to crossover study design with three study arms (No nap, brief nap, longer nap). In this sequence, participants will perform the 12-hour night shift with no nap first, undergo a 1-week minimum washout, then complete the protocol again with a longer nap, then undergo a minimum 1-week washout, then return to complete the protocol again with a brief nap opportunity.

Behavioral: Intra-Shift Napping

Brief nap, no nap, then longer nap

EXPERIMENTAL

Participants will be monitored for 72 total hours, including a 12-hour simulated night shift. At baseline (consent), participants randomized to crossover study design with three study arms (No nap, brief nap, longer nap). In this sequence, participants will perform the 12-hour night shift with brief nap first, undergo a 1-week minimum washout, then complete the protocol again with no nap, then undergo a minimum 1-week washout, then return to complete the protocol again with a longer nap opportunity.

Behavioral: Intra-Shift Napping

Brief nap, longer nap, then no nap

EXPERIMENTAL

Participants will be monitored for 72 total hours, including a 12-hour simulated night shift. At baseline (consent), participants randomized to crossover study design with three study arms (No nap, brief nap, longer nap). In this sequence, participants will perform the 12-hour night shift with brief nap first, undergo a 1-week minimum washout, then complete the protocol again with longer nap, then undergo a minimum 1-week washout, then return to complete the protocol again with no nap opportunity.

Behavioral: Intra-Shift Napping

Longer nap, brief nap, then no nap

EXPERIMENTAL

Participants will be monitored for 72 total hours, including a 12-hour simulated night shift. At baseline (consent), participants randomized to crossover study design with three study arms (No nap, brief nap, longer nap). In this sequence, participants will perform the 12-hour night shift with a longer nap first, undergo a 1-week minimum washout, then complete the protocol again with a brief nap, then undergo a minimum 1-week washout, then return to complete the protocol again with no nap opportunity.

Behavioral: Intra-Shift Napping

Longer nap, no nap, then brief nap

EXPERIMENTAL

Participants will be monitored for 72 total hours, including a 12-hour simulated night shift. At baseline (consent), participants randomized to crossover study design with three study arms (No nap, brief nap, longer nap). In this sequence, participants will perform the 12-hour night shift with a longer nap first, undergo a 1-week minimum washout, then complete the protocol again with no nap, then undergo a minimum 1-week washout, then return to complete the protocol again with a brief nap opportunity.

Behavioral: Intra-Shift Napping

Interventions

Intra-Shift Napping BEHAVIORAL

The Brief Nap opportunity will allow for a 30-minute nap between the hours of 0200 and 0400 during the 12-hour simulated night shift. The Longer Nap opportunity will allow for a 2-hour nap between the hours of 0200 and 0400 during the 12-hour simulated night shift.

Brief nap, longer nap, then no nap; Brief nap, no nap, then longer nap; Longer nap, brief nap, then no nap; Longer nap, no nap, then brief nap; No nap, brief nap, then longer nap; No nap, longer nap, then brief nap

Eligibility Criteria

• Age: 18 Years - 100 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• age 18 years or older;
• current / active certification as an EMS clinician at the EMT-Basic, Advanced, Paramedic, Flight Paramedic, or Flight Nurse level, or healthcare shift worker;
• has not ever been diagnosed with any of the following: hypertension, cardiovascular disease, myocardial infarction, stroke/TIA, chronic kidney disease, adrenal disease, thyroid disease, rheumatologic disease, hematologic disease, cancer of any type, dementia/memory loss, organ transplantation; insomnia or other major sleep problem; sleep apnea or other diagnosis that is related to problems with breathing or the airway; and
• is not currently pregnant.

You may not qualify if:

• years of age or younger;
• not an EMS clinician or inactive as an EMS clinician or not a healthcare shift worker;
• has ever been diagnosed with hypertension, cardiovascular disease, myocardial infarction, stroke/TIA, chronic kidney disease, adrenal disease, thyroid disease, rheumatologic disease, hematologic disease, cancer of any type, dementia/memory loss, organ transplantation; insomnia or other major sleep problem; sleep apnea or other diagnosis that is related to problems with breathing or the airway;
• is currently pregnant;
• is unwilling to wear multiple monitoring devices (e.g., automated blood pressure monitoring device, holter monitor for HRV measurement, wrist actigraphy) for the duration of the study protocol.
• is unwilling to refrain from caffeine during the study protocol; or
• is unwilling to adhere to sleep / wake times outlined in the study protocol.

Sponsors & Collaborators

• University of Pittsburgh: lead
• ZOLL Foundation: collaborator

Study Sites (1)

University of Pittsburgh

Pittsburgh, Pennsylvania, 15261, United States

Location

Related Publications (3)

• Patterson PD, Weiss LS, Weaver MD, Salcido DD, Opitz SE, Okerman TS, Smida TT, Martin SE, Guyette FX, Martin-Gill C, Callaway CW. 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. Trials. 2021 Mar 16;22(1):212. doi: 10.1186/s13063-021-05161-4.

  PMID: 33726840 BACKGROUND

• Patterson PD, Okerman TS, Roach DGL, Hilditch CJ, Weaver MD, Patterson CG, Sheffield MA, Di Salvatore JS, Bernstein H, Georges G, Andreozzi A, Willson CM, Jain D, Martin SE, Weiss LS. Are Short Duration Naps Better than Long Duration Naps for Mitigating Sleep Inertia? Brief Report of a Randomized Crossover Trial of Simulated Night Shift Work. Prehosp Emerg Care. 2023;27(6):807-814. doi: 10.1080/10903127.2023.2227696. Epub 2023 Jul 17.

  PMID: 37347968 DERIVED

• Patterson PD, Okerman TS, Roach DGL, Weaver MD, Patterson CG, Martin SE, Okwiya N, Nong L, Eyiba C, Huff JR, Ruzicka A, Ruggieri J, McIlvaine Q, Weiss LS. Effect of Short versus Long Duration Naps on Blood Pressure during Simulated Night Shift Work: A Randomized Crossover Trial. Prehosp Emerg Care. 2023;27(6):815-824. doi: 10.1080/10903127.2023.2227891. Epub 2023 Jul 17.

  PMID: 37347964 DERIVED

Study Officials

• Leonard Weiss, MD

  University of Pittsburgh

  PRINCIPAL INVESTIGATOR

• P. Daniel Patterson, PhD

  University of Pittsburgh

  STUDY DIRECTOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Masking Details: No masking
• Purpose: OTHER
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Assistant Professor

Model Details: Randomized crossover study design

Study Record Dates

• First Submitted: July 9, 2020
• First Posted: July 14, 2020
• Study Start: March 1, 2021
• Primary Completion: October 2, 2022
• Study Completion: October 2, 2022
• Last Updated: May 6, 2023

Record last verified: 2023-05

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP
• Time Frame: One year after the main results are reported in peer-reviewed manuscripts.
• Access Criteria: The study team will develop a process to receive requests from outside the study team for de-identified datasets.

Locations

US (1)