Here are a couple of apps mentioned by Ruby Granger – gamify study, sleep and time away from your phone, helping to get better balance with your smartphone use.
Forest – Schedule time to stay off your phone and grow trees. The tree dies if you exit the app during the time you set – The better you are at this the bigger your forest becomes. It helps you to look back at how focused you have been (£1.99).
SleepTown – by same makers works in a similar way. You schedule your sleep and whilst you are off your phone a house is being built. The better you sleep the more elaborate your house. If you exit the app the house falls down (£1.99).