Maintain a regular schedule for meals, medications, etc., to keep your inner clock running smoothly. Don't consume caffeine or alcohol within a few hours before bedtime. Also, don't drink when you are sleepy since tiredness can intensify the effects of alcohol. Avoid smoking close to bedtime. Experiment with naps.
Some students sleep better with naps, and some sleep better without.
If you take naps, try to do so at the same time every day. Wake up early to do homework rather than staying up late at night. Relax before bed. Avoid reading or watching television, and try to not think about your worries. This aligns a person with the magnetic forces of the earth.