Going to bed at different times each night can be a warning sign for your heart. A study from the University of Oulu found that people who change their bedtime a lot have a much higher chance of serious heart problems.
The risk was especially high for those who slept less than eight hours each night. They were about twice as likely to have a heart attack or stroke compared to people with steady bedtime habits. Changing the time you wake up did not show the same danger.
Heart events in the study meant serious conditions that need hospital care, like heart attacks or strokes.
"We have known that odd sleep habits can hurt the heart, but this is the first time we looked at bedtime, wake‑up time, and the middle of sleep separately," said Laura Nauha, a post‑doctoral researcher at the university.
How Sleep Was Measured
Researchers used wrist‑worn activity monitors to track how long participants stayed in bed and when they fell asleep. The data showed that keeping a regular bedtime matters most for heart health.
"Regular bedtime seems to be a key piece of the puzzle," Nauha explained. "It reflects how steady our daily life rhythms are."
Long‑Term Study Details
The team followed 3,231 people born in Northern Finland in 1966. When the participants were 46 years old, their sleep habits were recorded for one week. Their health was then tracked for more than ten years through national health records.
The findings suggest that simple daily choices, like going to bed at the same time, can influence heart health for many years.