Are you responsible for a murder you commit in your sleep?
Dr. Riemann, should it be assumed that sleepwalkers mean well? If so, doesn’t somnambulism give murderers a free ride?
This kind of thing does happen, but very rarely. The decisive indicators at the trial of Kenneth Parks were that he had no motive and his testimony was convincing. Things were quite different for an English colleague of mine who was asked to provide an expert opinion in the case of a man who had killed his wife in the night. There again, the accused claimed that he had done it in his sleep. But then a witness testified to seeing the man dig a grave in his garden weeks earlier—also at night. It is extremely unlikely that a sleepwalker would first dig a grave in his backyard and then later on kill his wife while once again sleepwalking. In that instance, the man was convicted.
Do such sleepwalking cases ever involve children?
I remember a spectacular German case from 2002 in which a mother claimed her 12-year-old daughter had murdered her own father in her sleep. To support the mother’s claim, there had been testimony from a friend of the family that the girl walked in her sleep in addition to other testimony that she’d once entered her parents’ bedroom with a knife in her hand while she was sleepwalking. All the same, it seemed almost inconceivable that a child could kill a grown man in her sleep with a single stab wound to the heart. Evidence later pointed to the mother, whom a court convicted and sentenced to life in prison. But there have been genuine cases of violence perpetrated by sleepwalkers.
What do you do if a patient is a danger to others?
Imagine how you’d feel: You wake up suddenly to find your husband or wife with a strange and distant look on their face as they try to strangle you. You would no longer feel safe in your own bed after that. One patient had himself committed to our psychiatric clinic because he was so afraid of what he might do in his sleep. When he went home on weekends, we’d give him a restraining belt that only his wife could open. That made it possible for him to spend the night at home in their bed without having to be afraid that he might harm her during sleep.
Why do some people become violent in their sleep?
Let’s take the example of the man I just mentioned. He’d grown up in Los Angeles where his relatively affluent parents would often leave him home alone with his younger brother when they went out at night. He was always afraid of what might occur if someone tried to break in, so he’d always sleep with a baseball bat beneath his bed. The first time he tried to strangle his wife was not long after he proposed to her. When he came to see us for help we attempted to determine the psychological motivation behind his behavior and came to the conclusion that the impending marriage actually reawakened his erstwhile feelings of being responsible for someone else. So whenever he would feel threatened in the night for any reason and think that he had to defend himself against some imagined attacker, he would not immediately realize that it wasn’t an attacker at all but rather his own wife lying there beside him.
Is there always interaction between a sleepwalker and someone else?
Absolutely not. I would say that many somnambulists don’t even realize that they are sleepwalkers. Many of them live alone and have no idea that they are doing strange things in their sleep. Often they only realize this after they have fallen from a window in the night and injured themselves, for example. One of our patients almost suffocated after he’d tried to swallow food that was still in its plastic wrapper. Another one had woken up in the middle of the night to find himself sitting behind the wheel of his car. He had no idea how he got there.
Do patients sometimes feel as though they’re losing their minds?
We sometimes talk to patients who have been wondering for a long time about strange things that happen at home. Some have reported opening the refrigerator in the morning to find all the contents in a state of disarray:
things knocked over, a knife smeared with butter, etc. One young man told me that he emptied his ashtray every night only to discover cigarette butts in it the next morning. These sorts of events can really rattle people.
What influences the things people do in their sleep?
Often sleepwalkers will do the same things in their sleep that they’ve been doing during the day. One young man, for example, had recently moved into a new apartment. So what did he do in his sleep? He got up and slid the bed back and forth across the room with his girlfriend still in it, which he had been doing during the days while arranging furniture in the new space. Another young patient worked at a pharmacy where she spent her days dealing with the incoming shipments and putting medicines in the drawers where they belonged. So what did she do at night? She got up, walked over to her dresser, and sorted socks and underwear, moving them from one drawer to another. We often recall and perform a series of actions that we have practiced during the day.
But why would we want to perform these actions while we’re asleep?
Our sleep is cyclical, with its phases typically lasting between 90 and 120 minutes, but cycles vary from person to person and from night to night. A normal sleep cycle occurs in stages, from light drowsiness to deep sleep. Sleepwalking often happens early in the night, usually during deep sleep called N3. Because people get less N3 sleep as they age, sleepwalking is more common among children and young adults. Sleepwalking episodes can last a few seconds or a half hour or longer, but most last for less than 10 minutes. It’s often difficult to wake someone in such a state, but if you encounter a sleepwalker it is safe to wake the person, although he or she may feel disoriented if you do. All in all, sleepwalking needs to be more thoroughly studied because enough research has not been done.
Why is that?
Sleepwalking research is inherently difficult to conduct. Somnambulists rarely sleepwalk during a sleep study in the lab. And if a patient does get up to sleepwalk, the leads to the EEG get torn off. But I do recall an incident during a sleep study in Switzerland: A 16-year-old patient managed to sleepwalk without tearing off the leads, and the EEG continued to record his brain activity. It switched from smooth waves to a burst of the delta waves seen during deep sleep. There was activity in the cingulate cortex, which regulates emotions and motor functions, but no activity in the prefrontal cortex that governs higher mental functions.
Is it known why some people sleepwalk and others don’t?
If you perform an MRI on someone who sleepwalks, all the data will be completely normal. But we do know that sleepwalking has a genetic link. Some 80% of sleepwalkers have at least one other somnambulist in the family. And we know there are certain factors that promote sleepwalking— stress, lack of sleep, fever, alcohol, and certain medicines. There was a case of a woman, for example, who had been prescribed zolpidem, which is used to treat insomnia. The woman gained 50 pounds in a few months. She could find no explanation for her weight gain until she woke up in front of her fridge one night. Her doctor gradually discontinued the drug and her sleep-related activities stopped. Since April 2019 the FDA has required stronger warnings about the potential side effects of zolpidem (sold under the name Ambien) and other similar medicines, including sleepwalking and sleep-driving.
Could sleepwalking be prevented by inhibiting deep sleep?
There are medicines that can be used for that purpose, but only for a short period—for example, if a 9-year-old sleepwalker wants to go to summer camp and is afraid of waking up in an embarrassing situation. But such medicines can’t be used over a long period of time because deep sleep is vitally important. There are other medicines that relax or even impair the muscles, but these may have a wide range of side effects, including dependency, memory loss, and deep sleep interference. What’s more, they typically require ever-higher doses. So they are not a long-term solution. The best thing for a sleepwalker to do is to eliminate other contributing factors by getting enough sleep and curtailing use of alcohol and drugs. Sometimes napping during the day helps because it reduces the amount of deep sleep needed at night. Finding the solution requires experimentation for both patients and their doctors…