A new study released last week during the American Thoracic Society Conference in San Francisco associated sleep apnea and increased risk of cancer mortality.

Previous studies have associated sleep apnea with increased risks of hypertension, cardiovascular disease, depression and early death.

A team lead by Dr. F. Javier Nieto, chair of the Department of Population Health Sciences at the University of Wisconsin School of Medicine and Public Health, found a nearly five times higher incidence of cancer deaths in patients with severe sleep apnea compared to those without the disorder. Similar results were found in animal studies.

"These findings provide clues to help further our understanding of the relationship between sleep and health," Dr. Susan B. Shurin, acting director of the National Heart, Lung, and Blood Institute said in a prepared release. "It will be important to understand the relationship and mechanisms, if the association is confirmed."

The University of Wisconsin team collaborated with Dr. Ramon Farre, professor of physiology at the University of Barcelona, Spain. Farre’s research team also presented a study at the conference, showing the impact of sleep apnea on mice.

Other studies released at the conference showed the association between severe sleep apnea and diabetes and cardiovascular disease. Scientists also presented research looking at the association between sleep apnea and neurocognitive function in children and adults.