Table 4a. Association of Subjective/ Self-reported and Objective Sleep Duration with Endothelial Function (EF).

First Author, Publication Year, Study Type	Sleep Measurement	Non-Invasive Subclinical CVD assessment tools.	Results	Comments
Subjective/Self-reported Sleep Duration
Behl et al. (43), 2014	Self-Report (PSQI)	EF (FMD)	Total PSQI score was unrelated to brachial artery FMD; p = ≥ 0.05
Bonsen et al. (52), 2015	Self-Report questionnaire	EF (nailfold Capillaroscopy)	Sleep duration & endothelial function: regression coefficient 95% CI Men: β = −0.79, 95% CI (−7.20 to 5.63), p = 0.81 Women: β = −11.17, 95% CI (−21.80 to −0.55); p = 0.04	Significant only in women
Weil et al. (53), 2010	Self-Report questionnaire	EF [Endothelin (ET)-1 levels]	Sleep duration and endothelial function as ET-1-mediated vasoconstrictor tone: (Correlation) r = −0.32; p < 0.01	Increased ET-1 vasoconstrictor activity positively correlated with CVD risks.
Weil et al. (54), 2011	Self-Report questionnaire	EF [endothelial progenitor cells (EPCs) functions]	There were no significant correlations between sleep duration and any endothelial progenitor cells (EPCs) measure.	Circulating endothelial progenitor cells (EPCs) are vital to endogenous vascular repair processes and cardiovascular health.
Objective Sleep Duration
Cooper et al. (42), 2014	Polysomnography	EF (FMD)	Total sleep time (TST) was not associated with FMD: (Correlation) r = 0.03; p = ≥ 0.05