Users have reported that their iPhone's alarm system had stopped working properly and thereby had affected their schedule to wake up the next morning.

The issue may have been brought by the recent iOS update which Apple has launched as an overnight move. Overnight updates are said to be available beginning with iOS 9.0.

A number of users had reportedly turned to Twitter to express their dismay. One of them had been identified as Joey Santiago, the lead guitarist of Pixies.

"All of our iPhones alarms failed to wake up our household. Did anyone's iPhone alarm go off this morning?," tweeted Santiago.

All of our iPhones alarms failed to wake up our household. Did anyone's iPhone alarm go off this morning?

— Joey Santiago (@JoeySantiago) October 28, 2015

His tweet was then responded to by another Twitter user who also noted the occurrence of the same incident after he has upgraded. "@JoeySantiago Did you just upgrade? It happened to me after the last upgrade," tweeted Ed (@RealEdR).

@JoeySantiago Did you just upgrade? It happened to me after the last upgrade. — Ed (@RealEdR) October 28, 2015

Apple released the final version of iOS 9 in mid September which quickly followed with bug fix updates such as the iOS 9.0.1 and iOS 9.0.2 in the latter part of the month. The latest OS is touted as being full of enhancement features such as new multitasking, smarter Siri, new proactive suggestions, better security and stronger battery life.

"Keeping your devices and Apple ID secure is essential to protecting your personal information - like photos, documents, messages, email, and so much more," said Apple. "iOS 9 advances security by strengthening the passcode that protects your devices, and by making it harder for others to get unauthorized access to your Apple ID account. These new security features are easy for you to use. But they make it much harder for anyone else to access your personal information."

While it is true that the iOS 9.0.1 update that was issued in September had actually fixed some of the issues that are alarm-related, it has somehow failed to address the bug found in iOS 9.1 that was brought by the overnight update.

This isn't the first time that Apple has dealt with issues concerning time and alarm clock features of the iPhone. In 2010, the same issue was reported by users in Europe who noted how their alarms went off late by at least one hour.

One Twitter user still managed to bring in some humor that was brought by the alarm-killing overnight update of the latest iOS 9 version.

"My phone updated last night and shut my alarm off so I missed the ACT. But THANK god I have new emojis," tweeted Colin Michael (@ColinFilak).

My phone updated last night and shut my alarm off so I missed the ACT. But THANK god I have new emojis