Melatonin and its precursors. If behavioral changes do not work, it may be possible to improve sleep by supplementing with the hormone melatonin. Ideally it is best to increase levels naturally with exposure to bright sunlight in the daytime (along with full spectrum fluorescent bulbs in the winter) and absolute complete darkness at night. One should get blackout drapes so no light is coming in from the outside. One can also use one of melatonin's precursors, L-tryptophan or 5-hydroxytryptophan (5-HTP). L-tryptophan is obtainable by prescription only. However, don't be afraid or intimidated by its prescription status. It is just a simple amino acid.