Impact of Intra-Shift Napping on EMS Cardiovascular Health

NCT ID: NCT04469803

Last Updated: 2023-05-06

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 28 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2021-03-01
• Study Completion Date: 2022-10-02

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.

Detailed Description

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.

Critical questions remain:

Are BP dipping and HRV impacted by napping during night shift work? Compared to those who do not nap, does napping during night shifts help BP and HRV to normalize quicker in the hours immediately post night shift work? What is the impact of brief naps (e.g., 30 minutes) versus longer naps (e.g., 2 hours)?

This study will use a randomized crossover experimental design of EMS workers and be based in the laboratory environment. Participants will complete three intervention conditions. All study arms will involve a 12-hour simulated night shift. The intervention of interest is napping (no nap vs. a 30 minute nap vs. a two-hour nap) in a randomized crossover study design. The primary outcome of interest is BP dipping (>10% drop) and Heart Rate Variability (HRV) measured as the standard deviation of inter-beat intervals of the sinus beats in milliseconds (SDNN). All outcomes will be measured serially before the simulation, during simulated night shifts, during the intra-shift napping period, and during recovery.

Conditions

Blood Pressure; Heart Rate Variability

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: CROSSOVER
• Primary Study Purpose: OTHER
• Blinding Strategy: NONE

Study Groups

No nap, brief nap, then longer nap

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.

Group Type: EXPERIMENTAL

Intra-Shift Napping

Intervention Type: 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.

No nap, longer nap, then brief nap

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.

Group Type: EXPERIMENTAL

Intra-Shift Napping

Intervention Type: 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, no nap, then longer nap

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.

Group Type: EXPERIMENTAL

Intra-Shift Napping

Intervention Type: 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

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.

Group Type: EXPERIMENTAL

Intra-Shift Napping

Intervention Type: 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.

Longer nap, brief nap, then no nap

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.

Group Type: EXPERIMENTAL

Intra-Shift Napping

Intervention Type: 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.

Longer nap, no nap, then brief nap

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.

Group Type: EXPERIMENTAL

Intra-Shift Napping

Intervention Type: 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.

Interventions

Intra-Shift Napping

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.

Intervention Type: BEHAVIORAL

Eligibility Criteria

Inclusion Criteria

1. age 18 years or older;

2. current / active certification as an EMS clinician at the EMT-Basic, Advanced, Paramedic, Flight Paramedic, or Flight Nurse level, or healthcare shift worker;

3. 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

4. is not currently pregnant.

Exclusion Criteria

1. 17 years of age or younger;

2. not an EMS clinician or inactive as an EMS clinician or not a healthcare shift worker;

3. 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;

4. is currently pregnant;

5. 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.

6. is unwilling to refrain from caffeine during the study protocol; or

7. is unwilling to adhere to sleep / wake times outlined in the study protocol.

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 100 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

ZOLL Foundation

UNKNOWN

Sponsor Role: collaborator

University of Pittsburgh

OTHER

Sponsor Role: lead

Responsible Party

Leonard Weiss

Assistant Professor

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Leonard Weiss, MD

Role: PRINCIPAL_INVESTIGATOR

University of Pittsburgh

P. Daniel Patterson, PhD

Role: STUDY_DIRECTOR

University of Pittsburgh

Locations

University of Pittsburgh

Pittsburgh, Pennsylvania, United States

Countries

United States

References

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.

Reference Type: BACKGROUND

PMID: 33726840 (View on PubMed)

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.

Reference Type: DERIVED

PMID: 37347968 (View on PubMed)

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.

Reference Type: DERIVED

PMID: 37347964 (View on PubMed)

Other Identifiers

STUDY19120222

Identifier Type: -

Identifier Source: org_study_id