Lead author Edward Suarez studied 210 apparently healthy, middle-age men and women without any history of sleep disorders. None smoked, took any medications or were on hormone therapy.

The study found that about 40 percent of the men and women were classified as poor sleepers, defined as having frequent problems falling asleep, taking 30 or more minutes to fall asleep or awakening frequently during the night.

But while the sleep quality ratings of men and women were similar, they had dramatically different cardiac risk profiles.

For women, poor sleep is strongly associated with high levels of psychological distress and greater feelings of hostility, depression and anger. They had higher levels of all the biomarkers tests -- higher levels of C-reactive protein and interleukin-6, measures of inflammation that have been associated with increased risk of heart disease and higher levels of insulin.

"Women who reported taking a half an hour or more to fall asleep showed the worst risk profile," Suarez said in a statement.

The study was published in the journal Brain, Behavior and Immunity.