The man was let out into the yard for exercise on Wednesday evening, but was not let in again until 9am on Thursday, according to Dagens Nyheter.
Temperatures in the area fell to minus 8, according to Swedish weather service SMHI.
Hanna Jarl, director of the remand centre, referred The Local’s questions to the Swedish Prison and Probation Service’s head office. There, head of security Christer Isaksson was giving few details.
“The only information we are offering is that this man was found this morning, and we are putting all our efforts into finding out what happened,” he said.
Isaksson said that the man had been taken to Huddinge hospital, where he was treated for hypothermia, and was expected to be released during Thursday.
“He’s OK,” Isaksson said.
A preliminary investigation into the incident is expected to be completed within two or three days.