“…They did not study the dream characteristics of subjects with other sleep positions. Including sleepers who lie flat on their back or lie face down on the stomach, however, appears to be necessary for the investigation of the relationship between sleep position and dreaming because supine and prone positions can increase the risk for sleep paralysis (Cheyne, 2002; Dahmen & Kasten, 2001; Fukuda, Ogilvie, Chilcott, Vendittelli, & Takeuchi, 1998) and sleep apnea (Athanasakis, Karavasiliadou, & Styliadis, 2011; Bhat et al, 2006; Cartwright, 1984; Hershberger, Peeke, Levett, & Spear, 2001; Kim, Dhong, Lee, Chung, & Jung, 2011; Nakano, Ikeda, Hayashi, Ohshima, & Onizuka, 2003), both of which can be incorporated into persecutory dream images.…”