Last Updated on May 2, 2025
It seems like something out of a bad detective story, but as more and more people have begun taking prescription drugs with sleepwalking as a side effect, the number of crimes committed by sleepwalkers have dramatically increased over the last few decades and most commonly include offenses such as murder, sex crimes (a specific condition called sexsomnia results in this offense) and driving under the influence. That being said, while these parasomnia incidents are happening with increasing frequency, your defense attorney will still typically be hesitant to use the sleepwalking defense in most cases. Here’s what you should know.
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The Sleepwalking Defense Explained
The first thing that you should know is that, like the insanity defense, your attorney will likely be hesitant to use this defense strategy. “The sleepwalking defense is considered a long shot, very rarely applies to criminal cases, and there are usually better defenses available in most cases,” explains attorney Peter M. Liss, “However, if you actually committed a crime while sleepwalking, telling the truth might be the best course of action.”
Whether you commit a crime while awake or asleep, you should refuse to speak to the police without first discussing your case with a criminal lawyer.
Why do People Experience Parasomnia?
The reasons for sleepwalking vary. Some people are just naturally prone to it, some patients with Parkinson’s Disease develop the behavior as their condition progresses, and some medications (including anti-depressants and sleep aids) can actually cause sleepwalking.
“Ambien has caused some people to unconsciously do things like drive,” says Liss. “If someone drives under the influence of Ambien without knowing they were driving or that Ambien causes that type of behavior, it could be a defense to driving under the influence of drugs.” Of course, if other substances are found in the driver’s system it may defeat this defense —unless the person consumed these substances while sleepwalking.
Regardless of the cause, in most cases a person will know about the condition before he or she ever does something illegal while sleepwalking. A significant other, family member, or doctor aware of the condition could be a vital witness to someone trying to use a sleepwalking defense. In many cases, witnesses will recall seeing the person performing tasks in their sleep that they have no recollection of when they wake up.
Expert Testimony Can Make or Break a Sleepwalking Defense
Because these cases are so rare and so often misunderstood, your defense will usually require the testimony of an expert witness familiar with similar sleep disorders. He or she can attest not only to your behavior, but also to any underlying cause of your sleepwalking. In most cases, sleepwalkers will take a medication likely to cause sleepwalking, have a known history of night terrors as children, or have a family member who sleepwalks, as the condition is genetic. An expert witness can also be critical in establishing that you are not responsible for your behavior while sleepwalking, even if witnesses believed you were in control of your mental state at the time.
Before the expert witness testifies, they may need to perform a sleep test to learn more about your sleep patterns and potential sleep disorders. These tests monitor your breathing, brain waves, heart rate, eye movements, behaviors, and more.
Real Life Examples of the Sleepwalking Defense
Shockingly, the use of parasomnia as a criminal defense in the US dates all the way back to the 1846 case of Massachusetts v. Tirrell. Albert Tirrell was accused of murdering a prostitute, nearly decapitating her in the process, and setting fire to the brothel where she worked. His lawyers successfully argued that he could not be found guilty because he was a chronic sleepwalker and committed the crime while asleep.
Nearly 150 years later, a Canadian man named Kenneth Parks used the sleepwalking defense against allegations that he killed his mother-in-law. He drove 17 miles to their home, strangled his father-in-law, beat his mother-in-law with a tire iron, and stabbed both in-laws —all while allegedly asleep. While the story sounds far-fetched, his defense was strengthened by the police observing that he seemed confused about what happened and didn’t seem to notice that he severed tendons in both hands. He was acquitted of the charges.
An example of an unsuccessful attempt at the insomnia case involved a man named Stephen Reitz, who killed his lover on a trip to Catalina Island in 2001. He beat her and stabbed her multiple times in the neck, and then told police he was dreaming and thought he was in a fight with a male intruder. While Reitz’ parents testified that he had a history of sleepwalking since childhood, the prosecution presented evidence that he had previously abused his victim, even breaking into her apartment and threatening her with a knife. The jury found him guilty of first-degree murder.
Do Not Attempt a Parasomnia Defense On Your Own
“Even the slightest detail could work for or against you if you attempt the sleepwalking defense,” warns Liss. Be sure to speak with a defense attorney as soon as possible if you have been accused of a crime that you may have committed while asleep.
If you have been accused of committing any crime while sleepwalking, criminal attorney Peter M. Liss can help you evaluate your options to come up with the best possible defense for your situation. Please call (760) 643-4050 to schedule a free initial consultation.
