WEDNESDAY, Dec. 1 (HealthDay News) -- Loud snoring, difficulty falling asleep and unrefreshing sleep are each significant predictors of the development of metabolic syndrome, finds a new study.

Metabolic syndrome refers to the presence of at least three of five risk factors for heart disease, diabetes and stroke. The risk factors are: excess abdominal fat; high triglycerides; low HDL ("good") cholesterol; high blood pressure; and high blood sugar.

U.S. researchers studied 812 people, aged 45 to 74, for three years and found that the risk of developing metabolic syndrome was more than two times higher than normal in those with frequent loud snoring, 80 percent higher in those with difficulty falling asleep, and 70 percent higher in those with unrefreshing sleep.

When they focused on the individual risk factors for metabolic syndrome, the researchers found that loud snoring significantly predicted the development of high blood sugar and low HDL cholesterol. Difficulty falling asleep and unrefreshing sleep did not predict any individual risk factors.

The findings, published Dec. 1 in the journal Sleep, highlight the importance of screening patients for common sleep complaints during routine doctor visits, according to the researchers.

"This is the first prospective study to show that a broader array of commonly reported sleep symptoms, including insomnia and sleep-disordered breathing symptoms, predict the development of the metabolic syndrome, a key risk factor for cardiovascular disease," lead author Wendy M. Troxel, an assistant professor of psychiatry and psychology at the University of Pittsburgh, said in an American Academy of Sleep Medicine news release.

"It was rather striking that the effects of difficulty falling asleep and loud snoring were largely independent of one another," she added.

More information

The American Academy of Family Physicians has more about metabolic syndrome.