The alarm clock didn't go off.
He was awakened by unfamiliar breathing.
His eyelids were so heavy that they didn't belong to him. When he raised his hands, he saw a pair of completely unfamiliar hands. The joints, scars, and skin color were all familiar to him.
The memory of last night before going to bed is still clear, but this body belongs to another stranger.
That's it again.
Every sleep is a divestment. When you close your eyes, you are "I", but when you open your eyes, you are living in someone else's skin. He didn't know what this body was called, what kind of past it had, what grievances it carried, and who was sleeping next to it.
He can't mess up other people's lives, nor can he leave any traces of his own. When dawn comes, the next time he falls asleep, he will be thrown into another person's life.
There is no place to return to, no appearance, and no one or thing that can be held for a long time. Even death doesn't know which body it belongs to.