Hi Avishek, as an aspirant you have to study alot to clear exam but effective study has more effect than studying the whole day. Here is a routine you can follow which might help you in study:

• Even if you can't wake up early, try to wake up 6 am and take 5 min rest and enjoy the sound of nature. 
• Then meditate for 10 minutes and then fresh n up and take a bath.
• Eat a light breakfast and start studying from  8 am. Start from a quick revision (what you have studied last day). And pick up an easy topic to boost your mind.
• Study till 12pm with 10 minutes in every 1 hour.
• Take half and hour break, then again start studying from 12:30pm till 2:30pm. Take tough topics or subject to study.
• Have a break and eat your lunch and take a nap for atleast half an hour.
• Start studying again from 3:30 pm  to 5 pm.
• Take a break and go for a walk or listen to the music or play a non toxic game and relax yourself.
• Again start studying from 6 pm and study till 9 pm.
• Take a break and eat your dinner and again start studying from 9:30pm to 1am (because you are a night person).
• From 12am to 1 am revise what you have studied the whole and sleep with a positive thought. It will boost your next day.

All the best for your exam and life.