iOS 9.3 on iPhone 5 (Night Shift option is unavailable) I recently updated my iPhone 5 to iOS 9.3 and there is a new functionality introduced as "Night shift" option.

However it is not available on my iPhone 5
Any thoughts as to why?
It's not an error – it's because of the processing architecture. The iPhone 5 is an older model, and Apple isn't going to support 32-bit devices for Night Shift.