Follow a sleep pattern instead of staying awake late night. Always sit on a chair instead of bed to study. See that you keep your study table and room clutter free . Have small meals and not too heavy ones . Stay hydrated and also keep your room well lit and ventilated. Avoid screens , mobiles, TV etc . Do some meditation and pranayam as well in between. Get up and roam about after each chapter is over . Try to remain stress free . All the best