There's good news for the 30 per cent or more of adults who suffer from insomnia--difficulty falling asleep, waking up for prolonged periods during the night or unwanted early morning awakenings.

New research from St. Michael's Hospital has found that insomnia does not put them at increased risk of developing high blood pressure.

Dr. Nicholas Vozoris, a respirologist at St. Michael's, said there is growing concern among patients and health care providers about the potential medical consequences of insomnia, especially on the cardiovascular system.

If there were a link, this would have at least two major implications for the health care system. First, because insomnia is a common problem and often chronic in duration, a large portion of the population would need long-term screening for the possible development of high blood pressure.

Second, doctors might prescribe sleeping pills more often in an effort to treat insomnia from a possible blood-pressure lowering perspective. Dr. Vozoris said sleeping pills are already used too often and associated with a number of serious side effects, including addiction, overdose, car accidents and falls.

Dr. Vozoris said previous studies that suggested a link between insomnia and high blood pressure were often based on small numbers of people. He examined data from nearly 13,000 Americans who participated in the National Health and Nutrition Examination Survey, a series of studies designed to assess the health and nutritional status of adults and children in the United States. The survey is unique in that it combines interviews and physical examinations.

Participants were asked about their insomnia symptoms, and their responses were correlated with whether they had doctor-diagnosed hypertension, were taking anti-hypertension drugs, or had measured high blood pressure.

"After adjusting for many factors, including whether or not participants were receiving blood pressure pills or sleeping pills, there were generally no associations between insomnia and high blood pressure, even among people who were suffering from insomnia the most often," said Dr. Vozoris. "These results should reassure patients and their doctors that insomnia and high blood pressure are unlikely to be linked."

His findings were published in the Journal of Clinical Psychiatry.

The study is believed to be the first to examine for hypertension among individuals who self-reported various frequencies of insomnia symptoms.

"Patients who are suffering from insomnia and physicians who are trying to take care of them shouldn't worry so much about insomnia affecting their heart in an adverse way," he said.

"By showing there is no link between this very common sleep disorder and high blood pressure, physicians can be more selective when prescribing sleeping pills and refrain from prescribing these medications from a cardio-protective perspective."