The alarm, built into the Clock app of the device, is the wake-up tool of choice for many iPhone users.
However, in recent days, a number of iPhone users have reported that their alarms have not gone off, causing them to be late for work and school.
Apple has confirmed it is aware of the issue, and said it is working to quickly fix it.
It remains unclear how many people have been affected, what may be causing the issue, or what, if anything, users can do to remedy it.
It has also not been confirmed if the bug is restricted to particular iPhone models or a specific version of its iOS software.
Some social media users have suggested that turning off the iPhone’s “attention aware features” has helped them solve the issue – when active this tool checks whether a person is paying attention to their device and if so automatically tweaks some settings, including lowering the volume of alerts or alarms.
Users are also being encouraged to double-check their alarms before going to bed – ensuring their settings are correct and the volume is turned up.
