Inactivity reboot" effectively puts iPhones in a more secure state by locking the user's encryption keys in the iPhone's secure enclave chip.

Magnet Forensics have confirmed this feature for themselves, and noted that iOS 18 initially set the reboot time for seven days. However iOS 18.1 shortened the countdown to three days, and pointed out there are no prompts or warnings that give any indication an automatic restart is on the way.

Apple has quietly added a new security feature in iOS 18.1 called Inactivity Reboot. Here's what you need to know.

With iOS 18, Apple introduced a feature that causes the iPhone to reboot every three days, security researchers have confirmed (via TechCrunch). In

A new iPhone security feature in iOS 18 will make it tough for forensic analysts to obtain data from a locked device

However, the explanation is actually much simpler. Referring to the feature as an "inactivity reboot," AppleInsider says that this reboot timer isn't based on network connectivity or the phone's charge. Rather, the reboot simply occurs after a specific length of time -- around 96 hours.

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Apple covertly inserted a new security feature in iOS 18.1 that automatically prompts iPhones to reboot after 72 hours of inactivity. Read more here.