Irregular sleep timing tied to heightened risk for diabetes

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Swings in sleep patterns have health implications for women.
Swings in sleep patterns have health implications for women.

Going to bed too early or too late has health implications even for non-shift-working women, according to a study published in Sleep.

Widely varying or late bedtimes were associated with higher insulin resistance, while going to bed earlier than usual was associated with higher body mass index in midlife.

Researchers at the University of Pittsburgh used data from the SWAN Sleep Study to review sleep habits of 370 Caucasian, African-American and Chinese non-shift working women between 48 and 58.

Their self-reported bedtimes were used to calculate four measures of sleep timing: mean bedtime, bedtime variability, bedtime delay and bedtime advance. BMI and insulin resistance were measured at baseline and five years later.

The link between those measures and health impacts were noticeable only when researchers looked at weekday and weekend sleep patterns, meaning big swings in bedtime between work days and off days likely contributed to impaired glucose regulation.

“The results are important because diabetes risk increases in midlife women,” said senior author Martica Hall, Ph.D., professor of psychiatry at the University of Pittsburgh. “The good news is that sleep timing is a modifiable behavior.”

The researchers theorize that shifting schedules expose the body to varying levels of light, a cue that regulates circadian timing.