Question: what over the counter medication makes you sleepy?
Answer: Diphenhydramine (Benadryl, Aleve PM, others). Diphenhydramine is a sedating antihistamine. ... 
Doxylamine succinate (Unisom SleepTabs). Doxylamine is also a sedating antihistamine. ... 
Melatonin. The hormone melatonin helps control your natural sleep-wake cycle. ... 
Valerian.