Nytol One-A-Night 50mg Tablets 20'sNytol One A Night is a clinically proven sleep aid that helps you drift off, sleep soundly and wake up refreshed after a full nights sleep. Used to relieve temporary sleeplessness. Lets get a little sciencey for a second. Nytol One A Night contains a commonly used antihistamine called diphenhydramine hydrochloride (trust us its easier to use than to say!) It works by blocking the normal actions of histamine, the chemical that stimulates arousal