A long-term Finnish study has found that inconsistent bedtimes during middle age can nearly double the risk of serious cardiovascular events. People who varied their sleep times widely and spent less than eight hours in bed faced the greatest danger.
Researchers at the University of Oulu followed 3,231 people born in Northern Finland in 1966. They recorded sleep patterns with activity monitors for one week when participants reached age 46 and then tracked health outcomes through medical registers for more than ten years. Major events included heart attacks and strokes requiring hospital care.