David Kelly already had 24 convictions for residential break-ins on his record and was out on licence from a previous prison sentence when he targeted the flat in South Shields, on May 17.
Newcastle Crown Court heard the mum who lived there had left the property with her son that morning and noticed Kelly, who was acting strangely, running up and down the street, trying car doors and looked like he was on drugs.
Just over an hour later, the 41-year-old was seen by a neighbour to enter the victim's flat, while she was still out, and the police were called.
Prosecutor Omar Ahmad told the court an officer went into the flat and added: "The defendant was found inside, slumped against a wall. He was described by the officer as clearly intoxicated.
"He was arrested and taken into custody then later to hospital due to his level of intoxication."
Kelly, of no fixed address, later told police he had believed it was his friend's flat so had gone in and "slept to await his friend's arrival".
He admitted he had recently stopped taking drugs but on the night before the burglary had "slipped up" and taken "large quantities" of Valium.
The court heard the victim had been unwell in the months before the break-in and had been persuaded to go out for the first time that morning.
She was left wanting to move from her home because of the burglary.
Judge Paul Sloan QC sentenced Kelly, who pleaded guilty to burglary, to two years and five months behind bars.
The judge told him: "You were arrested inside the property and when interviewed you denied burglary, saying you had entered the house in the mistaken belief it belonged to a friend and had fallen asleep."
The court heard Kelly has convictions for a total of 169 offences, including the 24 burglaries.
Nothing was stolen during the break-in.
Nicholas Lane, defending, said Kelly is "devastated" to be back behind bars but has started to reduce his methadone intake and has an opportunity to betransferred to a prison for therapy.
Mr Lane added: "He hopes this will be the last time the court will see him."