Answer:
It is not necessary to study for 8 hours. If you have a good memory , you can learn and memorize things well. If you still wish to do so then try being productive. Take short breaks while studying. Science says that take a 5 minite break after studying for 25 minutes. Eat food rich in vitamins and the foods which can increase your IQ level. Study in a room without interacting with social media. Remove all distractions from the place you are studying.
Hope you find it helpful!❤