THURSDAY, April 9, 2026 (HealthDay News) -- Irregular sleep timing may increase the 10-year risk for major adverse cardiac events (MACE) among middle-aged adults, according to a study published online March 24 in BMC Cardiovascular Disorders.
Laura Nauha, from the University of Oulu in Finland, and colleagues examined how the regularity of wearable device-determined sleep timing (bedtime, wake-up time, and sleep midpoint) predicts incident MACE and cardiovascular disease mortality over a 10-year follow-up in midlife. The analysis included 3,231 participants followed from 2012-2014 through 2023.
The researchers found that irregular sleep timing was associated with an elevated risk, but only among participants whose sleep period was shorter than the group median of eight hours. Individuals with irregular bedtimes had a twofold higher risk for MACE versus those with regular bedtimes (hazard ratio, 2.01; 95 percent confidence interval [CI], 1.00 to 4.01; P = 0.049). Participants with irregular sleep midpoints also had a higher risk versus those with regular midpoints (hazard ratio, 2.00; 95 percent CI, 1.01 to 3.98; P = 0.048).
"Previous research has linked irregular sleep patterns to heart health risks, but this is the first time we've looked separately at variability in bedtime, wake-up time and the midpoint of the sleep period -- and their independent associations with major cardiac events," Nauha said in a statement.