Researchers at New England Research Institutes and Yale School of Medicine studied 1,709 men between 40 and 70 years of age and found six to eight hours of sleep to be most healthy, reported science portal EurekAlert.

In contrast, men who reported they slept between five and six hours per night were twice as likely to develop diabetes and men who slept more than eight hours per night were three times as likely to develop diabetes, lead researcher H Klar Yaggi said.

Previous studies have shown similar results in women. "These elevated risks remained after adjustment for age, hypertension, smoking status, self-rated health status and education," Yaggi said.