Substance abuse is one of the top non-combat medical conditions that result in hospitalization for U.S. troops, according to a new Pentagon report. Mood, anxiety and adjustment disorders also rank high on the list, Time reports.

“Mental disorders accounted for more hospital bed days than any other morbidity category and two-fifths (40.1 percent) of all hospital bed days,” the Pentagon’s Medical Surveillance Monthly Report stated.

According to the report, hospitalizations for mental disorders have increased by more than 50 percent since 2007. The report notes that the recent sharp increase in hospitalizations for mental disorders probably is due to many factors, including repeated deployments and prolonged exposures to combat stresses. Other reasons may include increased awareness about mental health issues in the military, more screening for and detection of mental disorders after combat, and decreasing stigmas and removal of barriers to seeking and receiving mental disorder diagnoses and care.

Three studies published in January show active-duty military personnel and veterans are prone to substance abuse, depression and suicide.

One study of almost 600 veterans returning from Iraq or Afghanistan found 39 percent of veterans screened positive for probable alcohol abuse, 3 percent for probable drug use, and 14 percent for probable post-traumatic stress syndrome.

A second study, of 678,382 active personnel, found major depression and substance use disorders have increased. A third study found suicide rates for all U.S. military services rose between 2005 and 2007, particularly for members of the regular Army and National Guard.