Hi,

Late night studies, as suested by the teachers of kota themselves, is  not good for health. It is said that studying late nights will deprive of your sleep. And at this stage 7 hours of sleep is very necessary. And if sleep for 7 hours after studying till 4 then you won't be able to perform well in the exams. Because your body has become habitual of the late night sleeping and late waking. 

It also somewhere has adverse effects on your body, which will ofc reduce the success rate of the students. So a good sleep of 7 hours from 11 o' clock to 6-7 o'clock is good for health. 

I hope I was able to clear your doubt

Thank You