Sleeping long hours one night but only a few hours the next can be unhealthy, with a new study finding "irregular" sleep patterns could be a risk factor for type 2 diabetes, published July 17 in Diabetes Care, Report informs via HeathDay News.

The results "underscore the importance of consistent sleep patterns as a strategy to reduce type 2 diabetes," said study lead author Sina Kianersi. He's a research fellow in the Channing Division of Network Medicine at Brigham and Women's Hospital in Boston.

The new study involved sleep and health data on more than 84,000 people enrolled in the ongoing UK Biobank Study. The Britons in the study averaged 62 years of age and none had diabetes as the study began.

For seven consecutive nights, the participants wore an accelerometer -- a watch-like device that monitors movement while in bed.

The researchers also tracked whether or not people developed type 2 diabetes over the next 7.5 years.

After adjusting for a bunch of possible confounding factors, Kianersi's team found a clear association between irregular sleep patterns and a heightened risk for type 2 diabetes.

"Irregular" sleep was defined as sleep duration that changed by an average of 60 minutes or more between nights.

Folks with an irregular sleep pattern were 34% more likely to develop type 2 diabetes compared to people whose nightly sleep didn't vary as much.

How might fluctuating sleep duration encourage diabetes?

The study couldn't answer that question, but the Boston team theorize that "circadian disruption and sleep disturbances" could play a role.