Effect of 12 weeks with a 30-min nap opportunity during the night shift of healthcare workers on early cardiovascular risk biomarkers: the NAPWORK study protocol of a randomised controlled trial.
This paper presents a protocol for a 12-week randomised controlled trial investigating whether a 30-min nap opportunity during night shifts can reduce early cardiovascular risk biomarkers, including endothelial dysfunction, in healthcare workers.
Key Findings
Background
Night shift healthcare workers commonly experience chronic sleep deprivation, with many nurses reporting sleep of less than 6 hours per 24-hour period.
Sleep deprivation is described as 'a common concern' among healthcare workers
The threshold of concern is defined as less than 6 hours of sleep per 24-hour period
This chronic sleep restriction is associated with long-term health issues including endothelial dysfunction
Endothelial dysfunction is identified as playing 'a key role in the development of cardiovascular diseases, arterial hypertension and type 2 diabetes'
Methods
The study will recruit 80 nurses and assistant nurses from interventional care units working 2×12-hour shift schedules.
Total sample size is 80 participants
Participants are nurses and assistant nurses from interventional care units
All participants work a 2×12-hour shift schedule
The trial duration is 12 weeks
Methods
The trial has two conditions: a 30-min nap opportunity in a dedicated quiet room with a bed versus a 30-min rest period in a break room as control.
Intervention condition: 30-min nap opportunity during night shift in a dedicated quiet room with a bed
Control condition: 30-min rest period in a break room
The design is a randomised controlled trial
The intervention period lasts 12 weeks
Methods
The primary outcome measure is endothelial dysfunction assessed through the reactive hyperaemia index using the EndoPAT device.
Endothelial function is measured via the reactive hyperaemia index (RHI)
The EndoPAT device is the specified measurement tool
Endothelial dysfunction is described as an early cardiovascular risk biomarker
This outcome was selected because the impact of napping interventions on endothelial function 'remains unclear'
Methods
Secondary outcomes include multiple cardiovascular risk biomarkers and subjective measures of sleep and fatigue.
Arterial stiffness measured via pulse wave velocity is a secondary outcome
Additional physiological secondary outcomes include blood pressure, heart rate variability, and proinflammatory blood parameters
Subjective secondary outcomes include self-reported fatigue, recovery needs, sleep quality, and sleepiness
All subjective measures will be assessed using 'validated questionnaires'
Methods
The study protocol received ethical approval from the institutional review board 'comité de protection des personnes EST III' and is registered on ClinicalTrials.gov.
Ethics approval reference: 23CH138
The protocol is 'in accordance with ethical principles established by the 18th World Medical Assembly (Helsinki 1964)'
Written informed consent will be obtained from all participants
Conclusions
The authors propose that if effective, napping interventions during night shifts could contribute to more sustainable and health-conscious shift work practices.
The intervention is framed as a potential 'countermeasure' to 'mitigate the deleterious effects' of night shift work
Potential beneficiaries are identified as 'both workers and the organisations that employ them'
The study aims to address whether napping 'can decrease cardiovascular risk through early cardiovascular biomarkers'
What This Means
This research describes the design of a clinical trial examining whether allowing nurses and other healthcare workers to take a 30-minute nap during their night shift can improve markers of heart and blood vessel health. Night shift workers, particularly nurses, frequently get less than 6 hours of sleep per day, and this chronic sleep loss has been linked to damage to the inner lining of blood vessels (endothelial dysfunction), which is an early warning sign for heart disease, high blood pressure, and type 2 diabetes. Eighty healthcare workers on 12-hour night shifts will be randomly assigned to either nap in a quiet room with a bed or simply rest in a break room for 30 minutes during their shift, over a period of 12 weeks.
The main thing researchers will measure is endothelial function — how well blood vessels respond to increased blood flow — using a specialized device called EndoPAT. They will also measure arterial stiffness, blood pressure, heart rate variability, inflammation markers in the blood, and ask participants about their fatigue, sleep quality, and sleepiness using established questionnaires. This combination of objective measurements and self-reported outcomes is intended to give a comprehensive picture of cardiovascular health changes over the 12-week period.
This research suggests that something as simple as providing a dedicated nap space during night shifts could potentially reduce cardiovascular risk for healthcare workers. If the intervention proves effective, the findings could support workplace policy changes that build structured nap opportunities into shift work schedules, benefiting both the health of workers and the functioning of healthcare organizations that depend on them.
Bouchou Y, Monnier M, Roche F, Pélissier C, Berger M. (2026). Effect of 12 weeks with a 30-min nap opportunity during the night shift of healthcare workers on early cardiovascular risk biomarkers: the NAPWORK study protocol of a randomised controlled trial.. BMJ open. https://doi.org/10.1136/bmjopen-2025-110108