New research suggests that people exposed to prolonged periods of shortened sleep have significant increases in blood pressure during nighttime hours.

Researchers found that during the nighttime, in the sleep restriction phase compared to the normal sleep phase, systolic (top number) and diastolic (bottom number) blood pressure averaged 115/64 millimeters of mercury (mm Hg) versus 105/57 mm Hg, respectively.

For the study, eight healthy participants between the ages of 19 and 36 participated in a 16-day impatient protocol, consisting of a four-day acclimation period followed by nine days of either sleep restriction (four hours of sleep per night) or normal sleep (nine hours of sleep per night), and three days of recovery. Twenty-four blood pressure monitoring at regular intervals was measured at each study phase.

"We know high blood pressure, particularly during the night, is one of the major risk factors for heart disease, and Americans typically do not get enough sleep," Naima Covassin, lead author of the study and a Mayo Clinic cardiovascular diseases research fellow, said in a statement. "For the first time, we demonstrated that insufficient sleep causes increases in nighttime blood pressure and dampens nocturnal blood pressure dipping by using a controlled study that mimics the sleep loss experienced by many people."

Furthermore, the expected fall in blood pressure during the night was suppressed when subjects had inadequate sleep. They also found that nighttime heart rate was higher with sleep restriction than in normal sleep.

The findings will be presented March 15 at the American College of Cardiology's 64th Annual Scientific Session in San Diego.