In a study of more than 4,800 men and women, aged 32 to 59, who got five hours of sleep a night or less, middle-aged participants were about 60 percent more likely to develop hypertension than those who slept six to eight hours.

But the researchers found no connection between sleep deprivation and hypertension in participants aged 60 to 86.

Researchers used data from a large epidemiological study, excluding from the analysis anyone who already had hypertension, and over the next eight to 10 years recorded the incidence of newly diagnosed cases of high blood pressure.

"It's been known for a long time that sleep disorders are associated with hypertension," said James E. Gangwisch, a postdoctoral fellow at Columbia's Mailman School of Public Health, "but that could be for reasons besides not getting enough sleep. This is the first study that shows a relationship between short sleep duration itself and high blood pressure."

However, while getting too little sleep was bad, getting more than the average amount of sleep was not protective. People who got nine or more hours of sleep were as likely to have high blood pressure as those who slept six to eight hours.