Reader Gabrielle wrote in to ask: “Why can't we wake a sleepwalker? Is it a can't do, or a shouldn't do?”
Despite urban legends claiming that waking a sleepwalker will send them into shock or give them a heart attack, it’s pretty much harmless. While you can wake them up, you probably shouldn’t, and that’s for both your benefit.
Waking a sleepwalker has never been shown to cause them any harm, but there’s plenty of potential for the person doing the waking to get hurt. Sleepwalking usually occurs during Stage 3 non-rapid eye movement sleep, also known as slow wave sleep, and this stage of sleep is very deep. While waking straight from stage 3 is difficult, it can be done—but doing so can leave a person in a state of cognitive impairment (sleep scientists call it sleep inertia) for around 30 minutes.
Sleep experts warn that forcefully bringing a person out of a deep sleep into this impaired state can cause them to become startled, confused or agitated. Not immediately recognizing you as someone they know, they may push you, strike you, or otherwise lash out at you. Even if they don’t react aggressively, some sleepwalkers have been known to drive or prepare meals in their sleep, and having a groggy, confused person behind the wheel or at the stove can be dangerous for them and for others.
Instead of trying to wake a sleepwalker, the Sleep Disorders Center at NYU recommends gently leading them by the arm to guide them back to bed.