The public alerted the police about a drunk man in central Uppsala at around 6 p.m. on Christmas Eve.
He was then taken into custody by a police patrol in accordance with the Act on the Care of Drunk Persons, said police spokesperson Magnus Jansson Klarin.
During a check of the detention facilities during the night, it was discovered that the man had suffered a cardiac arrest. He was taken to hospital by ambulance and pronounced dead.
The incident will be investigated.
