Mumbling fantastical gibberish; devouring blocks of cheese in the nude;
peeing in places that aren’t toilets; and jumping out of windows.
These are all things people have reportedly done while sleepwalking,
a behavior that’s mostly benign but can be dangerous in rare cases.
It's estimated that around 18% of people sleepwalk at least once in their lives.
So, what exactly is sleepwalking?
First, we have to understand just how many of our daily activities
do not require our active attention.
Your prefrontal cortex is your brain's conscious,
deliberate, decision-making control hub.
You might decide to get up and walk using your prefrontal cortex,
but the intricate coordination of sensory inputs and muscles
that follows does not require any attention.
Instead, it’s mostly executed by a network of specialized nerve cells
along the lower part of the brain and spinal cord,
sometimes called “central pattern generators.”
These areas govern automatic movements and basic actions related to survival.
People with a REM sleep behavior disorder may enact their dreams
while they’re in REM sleep,
usually keeping their eyes closed.
However, this is a separate condition.
Sleepwalking arises from a very different stage of sleep—
the deepest stage of non-REM sleep, which is called “slow-wave sleep.”
In this state, the cortex, including the prefrontal cortex,
is essentially turned off.
When someone is roused from this stage,
they’ll usually appear groggy before either dozing off again
or becoming fully conscious.
For that moment, though, they’re in an intermediate state
straddling sleep and wakefulness.
A sleepwalking episode is, essentially, an extreme, prolonged version of this.
When sleepwalking, the prefrontal cortex remains inactive,
so the person doesn’t possess executive, deliberate control over their actions.
But other parts of their brain are active.
And, as we know, the body is capable of a lot
without involving the prefrontal cortex.
Sleepwalkers avoid obstacles, walk, and speak—
though it's often nonsense.
Most sleepwalkers can do basic things,
operating in a peaceful, unemotional, dreamless state.
In rare cases, sleepwalkers perform more complex tasks like cooking and driving.
They're occasionally guided by physical urges,
like eating or pursuing sexual activities.
And some episodes involve the brain’s fight or flight system,
during which the person might suddenly perceive an imminent danger,
and vocalize, cry, or even jolt out of bed and run away.
These episodes, called “sleep terrors,”
are more common in young children and usually result naturally.
Indeed, sleepwalking is generally more common in children,
perhaps because the brain areas that control the transition
between sleep and wakefulness are still developing.
But the exact mechanisms that cause sleepwalking remain unclear.
Many cases appear to run in families, while others are more mysterious.
Anything that could lead to partial awakening
is thought to increase the likelihood.
This includes factors that promote deeper slow-wave sleep—
like sedatives, hot sleep environments, and operating on too little sleep—
or things that disrupt sleep— like stress and other sleep disorders,
such as sleep apnea and restless leg syndrome.
Doctors will usually evaluate these factors and promote habits
that aid in healthy sleep, such as exercise, stress management,
and a consistent and sufficient sleep schedule.
They’ll also often recommend safety measures,
like hiding dangerous items, installing door alarms and securing windows.
If this doesn't help, they'll consider certain medications.
But many of the available treatments for sleepwalking
haven’t yet been rigorously studied,
so how they work and how effective they are is not entirely clear.
So, what should you do if you encounter a sleepwalker?
A common misconception is that rousing a sleepwalker causes irreparable harm.
Fortunately, this is not true.
However, trying to forcefully wake them can cause confusion and distress.
The best practice seems to be to gently guide them back to bed;
and, if they resist, to simply ensure they’re safe until the episode resolves.