How much to sleep for vigorous study of iit 2018

7hrs are enough

7-8 hour are enough but dont care of sleep just prepare untill you are fully exhausted

Please do not focus on studying for 8 hours a day. It will be more benefitting if you focus on studying  particular topics every day.. Keep  a minimum time limit but don’t push yourself to work unrealistically everyday... Focus on smart work rather than hard work...