Going to bed at different times each night during midlife could be a warning sign for future heart problems. New research from the University of Oulu suggests that wide swings in bedtime may significantly raise the risk of serious cardiovascular events, especially for people who spend less than eight hours in bed.

The study found a strong connection between irregular bedtimes and an increased likelihood of major heart-related events. People whose time in bed was under eight hours and whose sleep schedules varied widely faced about twice the risk compared to those with more consistent routines.…