There appears to be a curious phenomenon that is causing some iPhone models to turn off temporarily at night, which can interrupt alarms and other iPhone features.
In a thread on Reddit, a user complains that two separate iPhone alarms in his home failed to go off. Several other users also chimed in with similar issues, and it turns out that some of the issues could be linked to the iPhone turning off at night. From Reddit:
Hijacking top comment. Check your battery settings and see if there is a gap during the night. Yesterday a lot of iPhones turned off for a few hours during the night. In my case the phone turned back on 1 minute before the alarm
Some other people noted having to put in their passcodes in the morning, an indication that the iPhone restarted or shut off during the night. 9to5Mac highlighted these issues earlier this week, and we've also experienced the problem here at MacRumors, as have multiple users on the MacRumors forums. From MacRumors:
So my iPhone 15 Pro Max with iOS 17.0.3 spontaneously rebooted last night (10. October around 01:00 AM CET). The same happened to 3 of my friends with the same iPhone and same iOS, and to someone else with an iPhone 13 Mini, also on the same iOS.
You can tell if your iPhone turned off at night by opening up the Settings app, navigating to Battery, and checking the charging status over the past 24 hours. If there's a gap, the iPhone was turned off for a period of time.
The problem affects iPhone 15 models, but it is also impacting other devices, suggesting that it's something in iOS 17. Not all users are experiencing the shutdown issues, nor does it appear to be happening every night.
It is not yet clear what is going on, and Apple has not commented.
