• People with irregular sleep schedules had a 26% higher risk of major cardiovascular events—including heart attacks, strokes, and heart failure—even if they got the recommended amount of sleep.
• Sleep regularity may matter just as much as sleep duration: going to bed and waking up at consistent times was linked to significantly better heart health outcomes.
• The study found a clear dose-response relationship, with higher sleep regularity scores tied to lower cardiovascular risk; an SRI score of 77.1 or above was associated with a 15–18% risk reduction.

https://studyfinds.org/irregular-sleep-risk-heart-disease/