The term used is "somnambulism" (Latin. literally sleep walk), and is a medical and
psychological condition wherein the person is up and active, but usually has no conscious memory of these periods of activity. They are not technically "still asleep", but have aroused from deep (slow wave) sleep into a semi-conscious state.
A common term would be sleep walker.
A person who walks aimlessly can be referred to as a wanderer or a stroller.
well a person that can't sleep has insomnia.
a walker
the word is SOMNAMBULISTA somnambulist
A person who finds it hard to sleep is called an insomniac.
A person who loves to sleep or a person who has an obsession with bed rest is called a "CLINOMANIAC."
acrobat
An insomniac
When you can't sleep you might have insomnia so a person who can't sleep might be called an insomniac.
In the UK - we call them an 'out-patient'.
An idiot. But generally speaking, a person walking the street is called a pedestrian.