[47] Garu A, Nitta E, Yoshida Y, Yata E, Tsunematsu A, Araki T, Nagai A, Yano S. Does overnight duty affect vascular endothelial function? BMC Cardiovasc Disord. 2021 Sep 27;21(1):467. doi: 10.1186/s12872-021-02277-y. PMID: 34579658; PMCID: PMC8474775. RefID—167 PMID—34579658
Study Setting	Clinical research laboratory, Shimane University Hospital, Japan
Eligible Participants	Healthy volunteers over the age of 20 years who had nighttime duty from Shimane University Hospital.
Study Aims	The primary endpoint in this study was the changes in endothelial function after overnight duty. The secondary endpoint was the relationship between endothelial function and fatigue or sleep.
Study Design & Participants	Healthy volunteers were recruited over the age of 20 years who had nighttime duty from Shimane University Hospital. In total, 13 individuals participated in this study with a mean age of 31.6 ± 8.6 years. Investigators used an observational study design and sought to capture a total of six EndoPAT measurements for each subject (three measurements before daytime work and three measurements after nighttime work). Duration of shifts was not reported. All measurements were independently performed in the morning before breakfast. The method of measuring sleep during nighttime work was not reported, yet findings of sleep during nighttime work appear in Table 1 in Garu et al., 2021 [47].
Intervention/Exposure	Exposure of interest was nighttime work: duration of nighttime work was not reported. Sleep during nighttime work was assessed, but the methods of measurement were not reported.
Comparison(s)	After nighttime work, endothelial function was measured (three measures) and compared to a baseline measurement taken before daytime work (three measures).
Outcome Measure(s)	The primary outcome for this study was changes in endothelial function after overnight duty compared to baseline measures, as assessed via the EndoPAT device (outcome reported as Reactive Hyperemia Index RHI).
Key Finding(s)	As reported in Table 1 of the paper, RHI: Before duty 2.12 ± 0.53, after overnight duty 1.97 ± 0.50, p-value = 0.21. Sleep hours before duty 6.0 ± 1.2, sleep hours after overnight duty 2.3 ± 1, p-value < 0.05.