When left idle for a set period of time, the iPhone’s screen locks and the device enters sleep mode to conserve battery power. The feature, called Auto-Lock, include a few customization options to help set the length of time it takes for the iPhone to enter sleep mode. For instance, you can set the device to automatically lock when idle after as little as 1 minute or as long as five minutes. You can also disable the feature. Warnings Writer Bio

How to Increase the Time on an iPhone For Sleep Mode - 33