I think give a defined time for study, and only for that time study effectively. Just like school . we stayed at school for some defined hours so we are programmed no matter what to go school everyday at that time. So identify study time, it could be in the mornings. From 2-6 then in the afternoon 8_ 11 based on your productive time. Then follow it , even when you don't feel like studying don't spend these times doing other things. Once you adapt it you can increase the time and efficiency.