Tapas Das , IIT Madrad answers:
Its not only about JEE, being a student, i can say a good 5-6 hours sleep is needed everyday. I have prepared and qualified quite a few competitive exams in India, and i can understand the mental stress one has to handle for this.Sleep is the time when can forget the stress. Or you can take it this way.You study a mix of things during the day, and during sleep your brain go through the data and sends it to particular module, so that when you need it, you can get it easily.A good sleep during preparation of exam makes you feel relax in morning, which helps your intake capacity and concentration.Not only for exam, even if you have any important work, taking a good sleep in night makes you rejuvenated in morning. I have seen many of my friends studying all night and going to bed in morning. They say tha’ts the time they can concentrate and they can’t change. I will say change this habit now. Wake up at 6 after good 6 hours sleep, and start studying. See the effect and you yourself can understand the difference.
One more thing I would like to add, when you are preparing for exams, take an hour break in the evening for some exercise. Don’t think it as waste of time. Our brain is like a machine and you have to give it some rest. So you give a rest and do some exercise, brain just regains its power to intake more.
Akhilesh Gandhi, IIT Bombay answers:
Extremely important! But you do not need the 8 hour sleep every day while preparing for the JEE.
Initially you should do with around 6 hours of sleep. Later, when the exams are nearing, you will have to manage with 4 hours of sleep.
Also, it will be great if you meditate for some time everyday.
As Tapas Das suggested, exercise will help you a lot and make sure you keep some time for exercise. It would be even better if you were to play some sport during that time rather than take a jog or hit the gym for exercise.
Disclaimer : This is not a rule. This is just my opinion.