Apple Inc got a wake-up call on Sunday, as iPhone users complained the New Year got off to a slow start because built-in alarms on their phones failed to wake them.
"We're aware of an issue related to non-repeating alarms set for January 1 or 2," Apple spokeswoman Natalie Harrison told Reuters in an e-mail.
"Customers can set recurring alarms for those dates and all alarms will work properly beginning January 3." She did not elaborate.
The British Broadcasting Corp reported the problem led many people to oversleep on the first two days of the New Year.
The anomaly appears to affect single alarm settings on the iPhone 4 and earlier models with software updates, the BBC said.
Britain's Daily Mail newspaper reported that thousands of people were late for work, airline flights and trains, as a result of the malfunction.
Previously, the iPhone's alarm system had problems recognizing daylight savings time, making it go off at the wrong time, according to media reports. Apple had sold more than 1.7 million iPhone 4s as of last June.