Apple promises a good night's sleep with new iPhone feature

'Night Shift' makes screen of mobile device redder at night, following research that suggests it can help with sleep

It's not often that a smaller update of iOS, Apple's operating system for mobile devices, comes with treats for users. But the forthcoming iOS 9.3, which has just been released in beta form to developers, comes with one big feature: a good night's sleep.

That's thanks to a new feature called Night Shift, which adjusts the colour balance of the iPad or iPhone's screen after sunset. The phone uses geolocation and its internal clock to tell when it's sundown, and then shifts the colours onscreen so they're warmer, with more orange and red tones and fewer blue and white.