Science never sleeps

Sleep Cycle alarm clock, free, iOS IF you worry you are getting too little or too much sleep, this app uses science – via the microphone – to wake you up at the best time.

It monitors your breathing, snores and movement through the night to rouse you when you are in the lightest sleep phase and your body is refreshed and ready to rise.

It is well rated by users, though it can struggle when there are two people in a bed, or pets roaming.