Any adult can buy OTC sleep medications at a store. OTC sleep aids often contain an antihistamine. This drug treats allergies, but it can also make you drowsy. Some people take melatonin or valerian supplements to help them sleep.
What is the strongest sleeping pill over-the-counter?
Doxylamine succinate is one of the most sedating antihistamines available over-the-counter (stronger than diphenhydramine).