I try 5mg of melatonin an hour before going to sleep. If i am really anxious maybe 100-200mg of L-theanine with the melatonin. Both are OTC wholefoods, CVS, Vitamin shoppe. If those don't work I take Doxylamine Succinate or Diphenhydramine for a day or two.. both make you drowsy when studying but heck its better than wasting a day cause u didnt sleep. Cardio exercise daily helps.