Why Do We Sleepwalk?

It’s pretty unnerving to hear that you got up and walked around while you were asleep, especially when you don’t remember doing any of it. But sleepwalking doesn’t mean you were secretly awake. Your brain just woke up in pieces instead of all at once.

The parts that control movement became active enough to get your body moving, while the parts responsible for awareness, judgment, and memory stayed mostly asleep. That strange split is what makes sleepwalking possible.

The Brain Only Partly Wakes Up

Sleepwalking usually begins during deep non-REM sleep. If the brain starts to wake from this stage but doesn’t complete the process, basic movement systems can become active before full awareness returns.

This is how a person can sit up, walk through a familiar room, open a door, or carry out another routine action without consciously deciding to do it. The brain doesn’t need your full attention for every familiar movement. It can rely partly on patterns it already knows.

More complicated thinking is still limited. A sleepwalker may seem confused, respond slowly, say something that doesn’t make sense, or continue doing something they would recognize as unusual if they were fully awake.

Why Their Eyes Can Be Open

A sleepwalker’s eyes are often open, which can make them look much more awake than they really are. But open eyes don’t mean the brain is taking in and interpreting everything normally.

The person may process enough of their surroundings to move through a familiar space, but not enough to fully understand what is happening. That’s why they may have a blank expression or react differently than an awake person would.

Why They Don’t Remember It

The parts of the brain involved in forming memories may not fully switch on during a sleepwalking episode. Even if a person walks, talks, or interacts with objects, the experience may never be stored as a normal waking memory.

So it isn’t always that the person forgot what happened. Their brain may not have recorded it clearly in the first place.

Sleepwalking also isn’t usually the same as acting out a vivid dream. It generally begins during deep non-REM sleep, not the REM stage associated with the most vivid dreaming.

Why It Happens To Some People

Scientists understand the basic process behind sleepwalking, but they don’t always know why a particular episode happens on a particular night. Some brains appear to be more likely to enter this mixed state, and that tendency can run in families.

Sleepwalking is also more common in children. Their sleep and waking systems are still developing, and they usually spend more time in deep sleep than adults do. Many children stop sleepwalking as those systems mature.

Anything that disrupts deep sleep can also make a partial awakening more likely. Sleep loss, stress, fever, changes in sleep schedule, certain medications, and other sleep disturbances can sometimes contribute. These factors don’t explain every episode, but they can create more opportunities for the brain to get caught between sleeping and waking.

That in-between state is the key to understanding sleepwalking. The body is awake enough to move, but the rest of the brain hasn’t fully joined it yet.

This article is for informational purposes only and is not a substitute for professional medical advice.