THURSDAY, Nov. 8 (HealthDay News) -- Energy drinks can cause sleep problems and daytime sleepiness among U.S. soldiers in combat zones, a new government study says.

Army researchers looked at soldiers deployed in Afghanistan in 2010 and found that 45 percent of them consumed one or more energy drinks a day and 14 percent consumed three or more a day.

Compared to those who consumed two or fewer energy drinks per day, soldiers who consumed three or more energy drinks a day were more likely to get four hours or less of sleep per night. They were also more likely to report sleep disruptions related to personal or combat stress and illness, and to fall asleep during briefings or while on guard duty.

The study was published in the Nov. 9 issue of the U.S. Centers for Disease Control and Prevention's Morbidity and Mortality Weekly Report.

High-caffeine energy drinks are becoming increasingly popular among U.S. teens and young adults, Robin Toblin, of the Military Psychiatry Branch at Walter Reed Army Institute of Research, and colleagues noted in the report.

The researchers said their findings show that soldiers consume high amounts of energy drinks during combat operations and that this is associated with sleep problems and daytime sleepiness.

Soldiers need to be educated about the potential harmful effects that consuming too many energy drinks can have on sleep and mission performance, and the need for moderation, the researchers concluded in a CDC news release.

More information

The Nemours Foundation offers teens advice about energy drinks and food bars.