Respected Sir/ Madam,
I write this email to mention that my name is ________ (name) having _________(Roll number).
I would like to inform you that I have an upcoming exam on date __/__/____ (date) of _______ (subject/course). Therefore, I request you to sanction study leave with effect from __/__/____ (date) till __/__/____ (date).
I hope that you will approve my leave request so that I can prepare for my exam with dedication and hard work. If you need any further information, please let me know at your convenience.
________ (Roll number),
________ (Contact details)