Thank you for asking! masturbation is a perfectly natural phenomenon but in limits. twice a week is what behavioural sciences recommend. There is no need to be anxious. Life is full of exams.Just work hardest possible. Instead of wasting energy on whacking off, use it to concentrate and focus. Remember masturbation leads to post masturbatory psychosis and depression and that adds to your anxiety and impairs memory. I recommend to rely on nocturnal emissions. Rest assured excessive masturbation wears a person out and drain the last ATP of the body which a person needs specialy in exam days. You can do it.