Best buy zopiclone online uk sleep medicines available without a prescription can contain L-tryptophan (Melatonin) or diphenhydramine, which is a type of antihistamine. Using an over-the-counter medicine now and then is okay. But sleep medicine works best as a short-term treatment combined with lifestyle and behaviour changes, Physical Activities can help you sleep better! Most over-the-counter sleep medicines can be used safely for 7 to 10 days.