The app failed to switch off at the specified time says many iPhone owners using the 'do not disturb' feature that prevents the phone from sounding or vibrating overnight.
"Woke up this morning and the iOS Do Not Disturb featured which was supposed to be turned off at 6:30am was still on at 8am," an Australian user wrote on a tech discussion forum Whirlpool.
According to the Australian, another users in Victoria and the Northern Territory have reported similar issues with the app, dubbed the "hangover" feature.
While most suspect the quirk is down to a software glitch, others have speculated it could be a specially designed New Year's Day present from Apple, the report said.
According to a user in Victoria, the iPhone maker 'intuitively knew that some people would be nursing hangovers so decided to make it a feature of iOS 6'.