Compared with normal sleepers, those with poor sleep and insomnia showed a significant association with lower flow-mediated disease levels, the most common method to describe endothelial dysfunction.
Data from the Penn State Child Cohort showed that individuals in young adulthood with insomnia are at an increased risk of cardiovascular disease—and, more specifically, endothelial dysfunction—independent of factors such as obesity, sleep apnea, and alcohol use.1
Presented at the 2022 SLEEP Annual Meeting, June 4-8, in Charlotte, North Carolina, patients with poor sleep (0.104 [±0.006]) and insomnia (0.092 [±0.008]) showed a significant association with lower flow-mediated dilation (FMD) levels (P-linear <.05) compared with normal sleepers (0.111 [±0.003]). Lead investigator Julio J. Fernandez-Mendoza, PhD, scientist-clinician, Penn State Health, and colleagues concluded that "these data further reinforce the need to include insomnia as a target in the preventative efforts for cardiovascular disease."
Using Doppler ultrasound to assess FMD, subjects with insomnia demonstrated significantly lower FMD levels in comparison with normal sleepers (P = .029). FMD is considered the most widely used method to test endothelial function since it is noninvasive, and measures the response to increased shear stress, commonly in the brachial artery. Square root of FMD (sqrt-FMD), another primary end point used to test the robustness of the analysis, remained significant and in the same direction upon further analysis (P-linear = 0.015).
The study included 200 individuals aged 20 to 30 years old who underwent a thorough clinical history and physical examination to ascertain the presence of sleep disorders and body mass index, in-lab polysomnography to ascertain the apnea/hypopnea index, and Doppler ultrasound for FMD. The presence of moderate-to-severe difficulties initiating and/or maintaining sleep were first identified, with physician confirmation used for diagnosis of insomnia.
Previous literature has shown that insomnia is associated with prevalent and incident cardiovascular diseases; however, there are a lack of studies specifically looking at the associations between subclinical cardiovascular measures such as endothelial function. One notably 2017 study led by Faye S. Routledge, PhD, RN, also showed that insomnia symptoms are associated with reduced FMD.2
That analysis included 496 working adults, 39.5% of whom had reported insomnia symptoms. Patients completed baseline demographic, clinical depression (Beck Depression Inventory II), anxiety (General Anxiety Disorder-7), sleep (Pittsburg Sleep Quality Index), and noninvasive endothelial function (brachial FMD) measures. After adjusting for age, baseline artery diameter, and dyslipidemia, participants who reported insomnia symptoms had lower FMD than those who reported better sleep (adjusted FMD means, 6.13% [±0.28] vs 6.83% [±0.26]; P = .035).2 The findings were significant as a 1% decrease in FMD has been shown to be associated with a 13% increase in the risk of future cardiovascular events.3