"Anxiety Disorders In-Depth"
 
http://health.howstuffworks.com/anxiety-disorders-in-depth2.htm

(Below is the last paragraph from the article at the link above):
 
Sleep disorders. Insomnia and excessive daytime sleepiness even within a month after a traumatic event are important predictors for the development of PTSD. One specific sleep disorder -- sleep apnea -- may even intensify symptoms of PTSD, including sleeplessness and nightmares. Sleep apnea occurs when tissues in the upper throat (or airway) collapse at intervals during sleep, thereby blocking the passage of air. In one study, 91% of crime victims with PTSD had either sleep apnea or a lesser condition that partially blocked the airways during sleep. In fact, in one study treatment of sleep apnea eased PTSD. Sleep apnea has also been associated with a risk for panic disorder. [For more information, see In-Depth Report #65: Sleep apnea.]


This article could be the basis of a good discussion....