Hello,

Good to see your passion and dedication towards your studies. I Hope you achieve what you wish for.

Coming to the point, studying for such immense hours is not suggested. As you said you can do smart studies but make sure to maintain your timetable and schedule well. You also need to balance other things like spending time for yourself and the things you like doing (can be your hobbies) in order to make yourself relieved and stress free. You can study for just few hours and get in AIIMS if you understand your topics well. So just take some time off to refresh your brain, study for the limited time (not for so many hours like 12, 13) and have a good sleep. It is important to have a good sleep as these things will effect your preparation and understanding capacity.

All the best! Happy studying.