People who suffer from both insomnia and obstructive sleep apnea are more likely to suffer from heart problems and are almost 50% more likely to die than those without either condition, say Flinders University researchers, who advise people being tested for one of the disorders be tested for the other.

"Insomnia and obstructive sleep apnea are the two most common sleep disorders, affecting 10 to 30% of the population, but people can often suffer from both at the same time," says Dr. Bastien Lechat from Flinders Health and Medical Research Institute: Sleep Health.

"Previously, little was known about the impact of co-morbid insomnia and obstructive sleep apnea (COMISA) but what we did know is that for people with both conditions, health outcomes are consistently worse than those with neither condition or those with either condition alone."

Now, in a new study published in the European Respiratory Journal, Flinders researchers have studied a large US-based dataset of over 5,000 people to understand the risks of COMISA.

The participants, aged around 60 years of age at the beginning of the study and 52% female, were followed for approximately 15 years, with 1,210 people dying during that time.

The results suggested that participants with COMISA were two times more likely to have high blood pressure and 70% more likely to have cardiovascular disease than participants with neither insomnia nor sleep apnea.

The study also showed participants with COMISA had a 47% increased risk of dying (for any reason) compared to participants with no insomnia or sleep apnea, even when other factors known to increase mortality were taken into account.

"This is the first study to assess mortality risk in participants with co-morbid insomnia and sleep apnea," says Dr. Lechat, who led the research.

"Given that these people are at higher risk of experiencing adverse health outcomes, it is important that people undergoing screening for one disorder should also be screened for the other."

While further research is needed to investigate what might be causing the higher mortality risk for those with COMISA, researchers say further investigation is also warranted to ensure treatments are working effectively.

"Specific treatments may be needed for people with co-occurring disorders so it's important we examine the efficacy of insomnia and sleep apnea treatments in this specific population," says Dr. Lechat.

The Adelaide Institute for Sleep Health at Flinders University is continuing to conduct research to understand the reasons that insomnia and sleep apnea co-occur so frequently, and to develop more effective treatment approaches.

"Co-morbid insomnia and obstructive sleep apnea is associated with all-cause mortality," by Bastien Lechat, Sarah Appleton, Yohannes Adama Melaku, Kristy Hansen, R Doug McEvoy, Robert Adams, Peter Catcheside, Leon Lack, Danny J Eckert and Alexander Sweetman is published in the European Respiratory Journal.