The research team used two large cohorts, the Sleep Heart Health Study (SHHS) and the Men's Osteoporotic Fracture Study (MrOS). The SHHS cohort included 1,785 men and 2,273 women, with a mean age of 62.4±11 years, 32.8% with a history of hypertension, and 5.6% with diabetes; the MrOS cohort included 2,193 participants, with a mean age of 72.6±5.4 years, 37.7% with a history of hypertension, and 7.8% with diabetes. The MrOS cohort consisted of 2193 participants, with a mean age of 72.6±5.4 years, 37.7% with a history of hypertension and 7.8% with diabetes.
The SHHS cohort was followed for 11±2.8 years and the MrOS cohort for 15.5±4.4 years. Using Kaplan-Meier analysis, the team found that δ-wave activity, a brainwave signature underlying deep sleep (higher δ-wave activity is associated with better sleep), was significantly associated with coronary heart disease, cardiovascular disease, and cardiovascular death.
In the SHHS cohort, low δ-wave activity was associated with a 46% higher risk of coronary heart disease, 60% higher risk of cardiovascular disease, and 94% higher risk of cardiovascular death;
In the MrOS cohort, participants with low δ-wave activity had a 79% increased risk of coronary heart disease, 43% increased risk of cardiovascular disease, and 66% increased risk of cardiovascular death; in addition, δ-wave activity was associated with stroke and all-cause mortality risk.
