Researchers found that middle-aged adults with irregular bedtimes had double the risk of heart disease over a decade compared to those with consistent sleep schedules, according to a study published in BMC Cardiovascular Disorders.
The study followed 3,231 Finnish adults born in 1966, who wore wrist sleep monitors for seven days to track bedtime and wake time. After a decade, researchers linked the sleep data to national health records for heart attacks, strokes, heart failure hospitalizations, and cardiovascular deaths.
Participants were grouped by bedtime consistency: regular (same time nightly), fairly regular (within one hour), and irregular (within nearly two hours). Even after adjusting for age and sex-related risk factors, the irregular bedtime group showed a twofold increase in heart disease risk.
The heightened risk was tied specifically to inconsistent bedtimes, not wake times, and was most pronounced in individuals sleeping fewer than eight hours per night. Dr. John La Puma, a board-certified internist and sleep specialist, noted that short sleepers with erratic bedtimes face compounded risk.
Why bedtime timing affects heart repair
The body’s master clock, the suprachiasmatic nucleus in the brain, coordinates nightly repair processes such as blood pressure dips, cortisol clearance, heart rate slowing, and blood vessel repair. These functions are timed to when a person falls asleep, making bedtime consistency critical for cardiovascular recovery.
What Which means for prevention
Experts suggest that maintaining a regular bedtime may be as important as sleep duration and quality for reducing heart disease risk. The findings highlight sleep timing as a modifiable factor in long-term heart health, particularly for middle-aged adults.
Does waking up at different times affect heart risk the same way?
No, the study found that irregular wake times did not predict increased heart disease risk, while inconsistent bedtimes did.
Can fixing bedtime lower risk for people who already sleep poorly?
The study suggests that improving bedtime consistency may help reduce risk, especially for those sleeping under eight hours, though it did not test interventions directly.
