Health is the prime factor which decides our sleep.
Daily five to seven hours sleep is enough for a normal student. If you are a student with allergy, asthma you need to sleep more.
If you are studying in the morning, take some light breakfast, some light snacks if it is in the evening. Avoid eating heavy meals as they can make your body and brain sluggish and this will lead you to make you slow or feel sleepy.
During your study hours take juicy fruits like grapes and oranges.
Have proper lighting in your room.
Keep your properties like bag, books, pen, notes etc. organized.
Don’t study with a blowing fan on your face it dries your eyes.