Inconsistent Bedtimes Double Heart Attack Risk: Study
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- University of Oulu researchers found that participants with highly variable bedtimes at age 46 faced roughly double the risk of major cardiovascular events over the following decade, with the effect concentrated among those who spent less than eight hours in bed.
- The longitudinal study tracked 3,231 individuals born in Northern Finland in 1966, measuring sleep duration and timing via activity monitors over a one-week window and monitoring health outcomes through national healthcare registers for more than 10 years.
- Postdoctoral researcher Laura Nauha said this is the first study to separately assess variability in bedtime, wake-up time, and sleep midpoint against cardiac events — and bedtime irregularity was the decisive factor, not wake-up time chaos.
- Major adverse cardiac events in the study included myocardial infarction and cerebral infarction, the researchers reported, and irregular wake-up times alone showed no clear association with cardiovascular risk.
- Nauha argued that bedtime regularity 'reflects the rhythms of everyday life — and how much they fluctuate,' positioning a consistent sleep schedule as a modifiable factor most people can influence.
- The findings were published in BMC Cardiovascular Disorders (2026), adding longitudinal evidence to prior cross-sectional links between erratic sleep and heart disease.
Why it matters: For adults entering midlife, the study identifies bedtime consistency — not total sleep or wake-up timing — as a potentially modifiable lever for reducing cardiovascular risk over the next decade. With 3,231 participants followed for 10+ years, the dataset gives Nauha's team rare longitudinal weight behind a recommendation most people can act on tonight.
