To walk around and do things while you are sleeping.
Sleepwalking can be scary for some people, but it is usually harmless.
Examples:
I sleepwalk at night.
She sleepwalks in her sleep.
Sleepwalking is when you walk and do things while you are sleeping.
My brother sleepwalks and talks to the wall.
Last night, I sleepwalked all the way to the kitchen and ate a sandwich.
He sleepwalks and thinks he's a robot.