Post traumatic stress disorder (PTSD) is becoming more frequent among our soldiers. I have had the honor of working with military personnel and their families at several bases in my career - McConnell AFB, Camp Lejune, and most recently at Fox at the Redstone Arsenal. Sleeping problems are common and many report that sleep issues worsen after returning from deployment. In particular, I hear that snoring and breathing problems tend to worsen after returning home.
This article describes an interesting finding. Soldiers diagnosed with PTSD and obstructive sleep apnea (OSA) present to my office regularly. This study showed that CPAP therapy reduces nightmare frequency in those with PTSD. It makes sense as OSA can be more severe in dream sleep. If your dream sleep is disrupted by breathing events, you may experience more dreams, as you may wake up more often in the middle of, or right after a dream. CPAP will reduce the breathing events and may let you sleep right through, so that you don't remember your dreams (and nightmares) as much. There may be other reasons that CPAP reduces dreams too. When someone stops breathing in their sleep, adrenaline surges. This adrenaline surge may increase nightmares, especially in those with PTSD. So CPAP may reduce the adrenaline surges, thereby reducing the nightmares.