Sleep Stages and CVD Risk Factors: Is the Association Modified by Sex?

Deep nonrapid eye movement (non-REM) sleep (N3) is associated with lower blood pressure (BP) in women, while more wake time after sleep onset is associated with higher BP in men, according to study results published in Sleep.

Researchers conducted a cross-sectional study in Brazil between 2019 and 2023 to determine whether several polysomnographic sleep characteristics were associated with cardiovascular disease (CVD) risk factors, as well as explore whether sex modifies these associations. Adults aged 18 to 91 without moderate-severe sleep apnea who were enrolled in the Baependi Heart Study, a family-based cohort study established in 2005, were included in the study. Sleep was measured using polysomnography, BP was measured, and fasting blood samples were collected. To examine associations between sleep and BP, linear and logistic regression models were used.

A total of 1102 participants (women, 64%; mean age, 47.1; hypertension, 53.3%) were included in the study. Among men and women, the mean total, N3, and REM sleep durations were 6.6 hours, 47.2 minutes, and 81.4 minutes, respectively.

Compared with men, women had lower BP, higher total cholesterol levels, higher high-density lipoprotein (HDL) levels, lower low-density lipoprotein (LDL) levels, lower triglyceride levels, higher N3 sleep durations, lower arousal index, and lower apnea-hypopnea index (AHI).

Among women, greater N3 sleep was associated with lower systolic and diastolic BP, as well as reduced risk for hypertension. For every 10 additional minutes of N3 sleep, systolic BP lowered by 0.4 mmHg (95% CI, -0.71 to -0.06 mmHg), diastolic BP lowered by 0.3 mmHg (95% CI, -0.47 to -0.03 mmHg), and hypertension risk decreased by 6% (95% CI, 0.89-0.98).

In men, longer wake after sleep onset was linked to higher systolic BP and a greater risk for hypertension. For every 10 additional minutes of wake time, systolic BP increased by 0.4 mmHg (95% CI, 0.03-0.70 mmHg) and hypertension risk increased by 7% (95% CI, 1.00-1.14).

The interaction between wake after sleep onset and sex was not significant. In addition, REM sleep, AHI, and arousal index were not associated with BP in either sex.

While an association was found between more wake after sleep onset and lower total cholesterol, no links were demonstrated between wake after sleep onset and HDL, LDL, and triglyceride levels. On average, an additional 10 minutes of wake after sleep onset was related to a 0.8 mg/dL decrease in total cholesterol (95% CI, -1.48 to -0.14). Similarly, higher AHI was also associated with higher total cholesterol and LDL.

Study limitations include the cross-sectional design and lack of 24-hour BP recordings. “Future, prospective studies should examine associations between sleep architecture and detailed measures of CVD risk in men and women separately,” the study authors concluded.