A very disconcerted patient of mine sent me the above clipping. She has Parkinson's Disease and REM Behavior Disorder (RBD) as a part of her symptoms overall. And now this sweet, older woman is terrified that she is going to "sleepwalk strangle" her grandchildren when she babysits. When she babysits her grandchildren overnight, she has come up with an ingenious solution and wants my approval: She plans to lock herself in her master bedroom at night, and her husband of 50+ years will sleep in the guestroom outside the locked room in case the grandchildren needed something in the middle of the night. She has asked my approval of the overall plan's logistics and on the specific sliding bolt lock she has found at Home Depot and whether she will open this lock in her sleep (versus an alternative combination lock-bolt system she found).
I felt very bad for her situation, or her perspective, rather.
I was trying to imagine this future situation where "scary" grandma locks herself in her room at night as though she were a werewolf or some other Wes Craven creature of the night. Definitely something more frightening than my grandmother's pantry of eternal cookies.
First of all, parasomnia is the term for abnormal sleep behavior in all its forms (other than things like epileptic events and movement disorders, etc... which aren't really called behaviors). We are referring to complex motor events resembling what someone might do while awake. Parasomnia literally means "next-to-sleep," like paranormal means "next-to-normal" or in this case, behavior outside of normal sleep behavior, or in the latter, something happening outside of the normal. Parasomnia come in two broad flavors: NREM and REM parasomnias. Either you do this during non-dreaming sleep (NREM sleep), or while you're dreaming (REM sleep--Rapid Eye Movement).
The actual prevalence of all parasomnic behavior happening sometime over a lifetime (ALL SPECTRUM AND FORMS OF BEHAVIOR, from soft mumbling to eating a stick of butter or driving a car) is quite variable, as high as 67% of the population in some studies, so it's relatively common. Actual lifetime sleep walking behavior is as high as 22% and at any given time affects 1.7% of the population, which is heavily skewed toward kids who make up a majority of these walkers. More complex behavior like eating in one's sleep (4.5%) and sexual behavior (7%) is relatively rare and more likely in the adult population.
For self-injurious behavior, the current prevalence in the population is only 0.9% and injuring someone else is only 0.4%. And of all self-injurious behaviors and injuries to someone else, almost 99.99% of reported incidents involved accidental quick punching out/thrusting out/kicking out/falling off the side of bed/tripping on something in one's sleep, or other such simple, abrupt, relatively non-complex behaviors. AND, these latter, injurious-type behaviors are more common in person's with co-morbid psychiatric disorders such as active depression, anxiety, PTSD, etc. which skews the probability this direction.
So I reassured the patient that probability is in her favor, since her grossest probability of even attempting the type of aggressive behavior she is concerned about is 4 x 10 to the negative 4th power in logarithmic terms, and there is lots of wiggle room for poor math which would push the probability to even lesser degrees. Even if we use this number, she still would have to attempt this behavior without the child waking up and waking her in the process; have to negotiate her house without accidental self-injurious behavior in the process such as tripping or bumping herself awake; not wake her likely curious husband while getting up; and assume that she will have a directed effort again the children as opposed the man with whom she's had 50+ years of marital arguments with. And... we are treating her with medication, since parasomnias are treatable, so she would have to fail this too.
No, I think they are quite safe. But I still thought you might find this interesting all the same.