Jeff wakes up in a cold sweat, heart pounding. He looks around his Brooklyn bedroom, trying to remember where he is. He's 32, not 22. It's been a decade since he was a scout in the army, and this scene is just a dream built from memories.

He's been getting this nightmare a lot lately, but that's not unusual. He gets combat nightmares pretty often, up to two or three times a week when he's stressed. Sometimes, he wakes up to find he can't move, and he feels like someone, or something, is trying to drag him out of his bed.

It's not unusual for veterans to have sleep problems after their service. In fact, according to Colonel Vincent Mysliwiec, a sleep-medicine specialist for the U.S. Army, it’s become increasingly common since 2006, due to the conflicts in Iraq and Afghanistan.

Traditionally, soldiers experiencing this sort of thing are diagnosed with post-traumatic stress disorder (PTSD) or a more traditional sleep disorder. But a recent study suggests some of them may have a new affliction: trauma-associated sleep disorder (TSD).

People dealing with TSD have vivid nightmares and a myriad of other sleep problems, including insomnia, anxiety, night sweats, thrashing, screaming, kicking, and punching while asleep. They often act out their terrifying dreams.

This can get extreme. Some soldiers wake up from nightmares about pummeling the enemy to find they've hurt their bed partners. One study participant came in after his wife woke up with bruising and a black eye, explaining that he started screaming and attacking the wall while asleep. When she tried to stop him, he starting hitting her.

“She got caught in the crossfire,” he said.

Doctors observed symptoms like this during the Vietnam War, but they were too focused on PTSD at the time to consider another classification, according to Mysliwiec. But TSD is different than PTSD: half of TSD sufferers don't have daytime PTSD symptoms such as flashbacks and severe emotional reactions to things that remind veterans of traumatic events. Doctors also sometimes attribute the symptoms to REM behavior disorder, a degenerative brain disease. But active young men rarely get REM behavior disorder. Nor do TSD sufferers fit the criteria for nightmare disorder, since people who just have nightmares don't typically move while they're dreaming.

"We knew [veterans] developed insomnia and sleep apnea, but we've never seen a truly unique sleep disorder related to a traumatic experience," says Dr. Mysliwiec, who headed the study.

Mysliwiec started to think about the possibility of an entirely separate disorder when he monitored a patient who screamed and yelled in his sleep. Even though complaints about sleeping issues are common among veterans, Mysliwiec thinks this may be the first time someone has observed this in a lab. It's hard for scientists to catch; veterans know labs are monitored, and they may feel safer in them, making it less likely they'll have these violent nightmares.