The study, published in the Journal of Medical Economics, found insomnia patients with mental health disorders were 36 percent less likely to receive medication for their sleeping problems than were patients with no mental health diagnosis. Those with anxiety were the least likely to receive a sleep aid, with a 45 percent decreased likelihood of receiving medication for insomnia.

"Insomnia can cause you to have anxiety and depression, and depression and anxiety can cause you to have insomnia. It's a chicken-and-egg type of story," senior study author Rajesh Balkrishnan of Ohio State University said in a statement.

"What this calls for is specific guidelines related to the treatment of insomnia that takes into consideration these different types of patients, because insomnia has become such a big public health problem."

Balkrishnan and colleagues collected data from the National Ambulatory Medical Care Survey, which tracks Americans' annual outpatient medical visits. The researchers identified 5,487 physician visits by patients with insomnia between 1995 and 2004, which was calculated to represent about 161 million U.S. patients over that 10-year period.