NORTH AMERICAN iPhone users have become the latest to find their daily schedules muddled up by a bug in the smartphone’s alarm clock function that causes it to overcompensate for the end of daylight savings time.

As we reported last week, countless Irish iPhone users had found themselves being woken up an hour late by their phones if their alarm clocks were set to automatically go off every morning without needing to be set in advance.

The bug originated, it appeared, from the fact that the alarm clock wasn’t programmed to understand how the phone would automatically change the time itself in order to account for the clocks going back – and thus set itself a further hour behind.

The end result was that European users last week, and North American users today, have found their phones’ alarms sounding an hour late – even though the time indicated on the alarm itself appeared correct.

So, for example, someone whose alarm was set to go off at 7am every day would have had their alarm remain silent until 8am – despite the phone itself saying that the alarm would sound at 7am.

The latest spate of victims of the bug become the third – or, arguably, the fourth – group with which the bug has wrought havoc.

When New Zealand users set their clocks forward an hour at the end of September, their alarms similarly overcompensated and woke them up an hour earlier – sounding at 6am, for example, when they were set to sound at 7am.

The same issue struck in Australia the following week. At the time, Apple told ZDNet Australia that a solution to the bug had been identified and that it would be included in a future software update.

That solution, however, has yet to be deployed – with Apple merely advising users to delete any recurring alarms before the clocks went back, and to manually re-enter them once the extra hour had been gained.

Because of the absence of a formal software patch, however, millions of iPhone owners in North America will find themselves unusually well rested, but unfortunately behind schedule, when their phones offer the same bug this morning.