Many take tea and coffee in excessive quantities; this kill the body’s capacity to sleep. Drivers who drive vehicles during nights take excessive tea and students who are preparing for exams also do the same. Do not avoid sleep, this is a great mistake. A person can live without food, but not without sleep. Many students have the habit of studying through the night and sleeping during the day. Most living beings, including birds and beasts, sleep during the night. A person, who reads in the night as a habit, is cultivating Rajasic and Tamasic qualities. Change this habit slowly. If you read throughout the night and sleep through the day, your retention of what you studied will not be very strong. If you must put in hard work, get up early, say 3 or 4 a.m. and study. After early morning study, do not go and sleep again. This is the Sathwik way of life.

- Divine Discourse, “My Dear Students”, Vol 2, Ch 2.