Energy drinks that are used to ward off sleep deprivation in the military are having long-term adverse health effects on soldiers, according to a study in the Military Medicine journal.

Over 600 male infantry soldiers, mostly aged 18 to 24, were surveyed on their energy drink consumption after their combat team returned from a 12-month deployment to Afghanistan. They were asked questions designed to analyze the association between energy drink use and sleep deprivation, depression, insomnia, anxiety, PTSD, alcohol abuse, fatigue, and aggressive behavior.

Nearly half of troops drink at least one energy drink per day during deployment, but seven months after being deployed, 16 percent of soldiers of them "consume two or more energy drinks per day in the post-deployment period." People in that group are more likely to say they suffer from mental health problems, anger-related behaviors, and fatigue.

The aggressive behaviors “are associated with being less responsive to evidence-based treatments for PTSD," the authors of the study wrote. Soldiers who say that they drink less than one energy drink per day report these issues at a much lower rate.

U.S. military officials have been warning soldiers about the effects of energy drinks since 2016, when a 2010 survey showed that almost 45 percent of deployed troops consumed at least one energy drink per day and nearly 14 percent reported drinking three or more per day.

“It is important that [service members] understand the risks associated with overuse," the study said. "The message that moderation is critical needs to be conveyed.”

Energy drinks are readily available for service members on deployment, especially the brand Rip It, which is referred to in the military as "crack." Along with the long-term effects of over-consumption of energy drinks, short-term effects can include increased blood pressure, panic attacks, heart palpitations, anxiety, dehydration, insomnia and bowel irritability.

The energy drink industry takes in $21 billion annually in the U.S.