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.

backgroundNight shift work is well known to cause health disruption in the short and long term. Among healthcare workers, sleep deprivation is a common concern with many nurses reporting sleep of <6 hour per 24-hour period. Consequences of this chronic sleep restriction have been associated with long-term health issues such as endothelial dysfunction, which plays a key role in the development of cardiovascular diseases, arterial hypertension and type 2 diabetes. While countermeasures such as nap at work have been suggested to mitigate these deleterious effects, the impact of such intervention on endothelial function remains unclear. Therefore, the aim of the present study will be to investigate the effect of a 30 min nap opportunity during night shift work on endothelial function in healthcare workers working in 12-hour shifts. METHODS AND ANALYSIS: A 12-week randomised controlled trial will be performed with two conditions: (1) a 30 min nap opportunity during night shift work in a dedicated quiet room with a bed and (2) a control condition including a 30 min rest period in a break room. A total of 80 nurses and assistant nurses from interventional care units working a 2×12 hour shift schedule will be recruited. The main outcome will be endothelial dysfunction assessed through the reactive hyperaemia index using the EndoPAT device. Secondary outcomes will include other cardiovascular risk biomarkers, including arterial stiffness (pulse wave velocity), blood pressure, heart rate variability, proinflammatory blood parameters, self-reported fatigue, recovery needs, sleep quality and sleepiness, which will be assessed using validated questionnaires. Our study will address whether napping on the night shift can decrease cardiovascular risk through early cardiovascular biomarkers, including endothelial function, arterial stiffness and heart rate variability. If effective, such interventions could contribute to the development of more sustainable and health-conscious shift work practices, benefiting both workers and the organisations that employ them. ETHICS AND DISSEMINATION: The study protocol is in accordance with ethical principles established by the 18th World Medical Assembly (Helsinki 1964) and received approval from an institutional review board 'comité de protection des personnes EST III' (23CH138). Written informed consent will be obtained from all participants. TRIAL REGISTRATION NUMBER: NCT05955729; ClinicalTrials.gov 2023-A01109-36 Registered on 21 July 2023.