“Studies have shown that sleeping in the supine position compared with the lateral position may double the apnea-hypopnea index in patients with OSA. Strategies to avoid the supine position include placing tennis balls in a sock or pocket and pinning or sewing them onto the back of a shirt; wearing vests with posterior bumpers; and using positional alarms, verbal instruction, and pillows. Because of poor long-term compliance, positional therapy is not routinely recommended over standard positive airway pressure therapy.” AAFP 2016
http://www.sleepeducation.org/essentials-in-sleep/sleep-apnea/treatment