sleep peril

I was pondering the injurious nature of being asleep last night, whilst awake early morning at 3-6am with an unrelated to sleep pain in my ear.  I was pondering it because each time I sleep for the past 3 days I wake up with a pain in my hip from sleeping. Did a bit o searching and noticed this abstract: Fractures no less! I wonder what the rate of accidentally biffing your beloved is, in say, the midst of an ambush dream? I suppose most people do not go to bed with a rolling pin, so that leaves only flailing arms and legs. I was also reading on polyphasic sleep patterns versus monophasic sleep and wonder how humans veered to one over the other.

A polysomnographic and clinical report on sleep-related injury in 100 adult patients

CH Schenck, DM Milner, TD Hurwitz, SR Bundlie and MW Mahowald
Department of Psychiatry, Minnesota Regional Sleep Disorders Center, Hennepin County Medical Center, Minneapolis, MN 55415.

In 100 consecutive adults who came to a sleep disorders center complaining of repeated nocturnal injury, polysomnographic study identified five disorders: night terrors/sleepwalking (N = 54), REM sleep behavior disorder (N = 36), dissociative disorders (N = 7), nocturnal seizures (N = 2), and sleep apnea (N = 1). Ninety-five patients sustained ecchymoses, 30 had lacerations, and nine had fractures.