The Stenungsund man said he got up early Sunday to take care of his dog and his 3-year-old son soon came downstairs and said there was a "ghost" in his bed, The Local reported Monday.
The father said he discovered the drunk passed out in the bed. He told the newspaper Aftonbladet he considered handling the matter without police, but changed his mind when he saw the mystery man had urinated on the mattress.
Police said the suspect, whose name was not released, was arrested on a trespassing charge.
The father said he will now be locking the doors of his home at night.