The University of Oulu Mar 30 2026 An irregular bedtime in midlife may signal an increased risk of cardiovascular disease. A new study from the University of Oulu suggests that large swings in when people go to bed could double the risk of serious cardiac events—particularly among those who get less than eight hours of sleep. The researchers found that inconsistent bedtimes and greater variability in sleep timing were strongly associated with a higher risk of major cardiovascular events,