Newcastle Crown Court heard how Tony Dodds got into the room of Matthew Davis, 39, and repeatedly hit him over the head as he slept.
The victim's body was not discovered at the guest house on North Parade, Whitley Bay, until two days later.
Dodds, 25, of Hillheads Road, admitted murder and was jailed for life. He must serve a minimum of 15 years.
The hearing was told that after attempting to enter the rooms of other tenants in March this year, Dodds managed to get into the room of Mr Davis.
The victim was punched, kicked and beaten over the head.
Dodds then tried to go into the guest house kitchen to make himself some food, the hearing was told.
Det Ch Insp Shelley Hudson, of Northumbria Police, said: "This was a truly cowardly attack on a vulnerable man.
"All of the evidence would suggest that he was attacked in his sleep - he had no defensive wounds and there was nothing to suggest a struggle took place.
"What's more it appears that Matthew's murder was without motive or reason."
She added that Dodds showed no remorse for the attack.
A man who broke into a guest house and battered a stranger to death with a wine bottle has been jailed for life.