Nytol Night Time Sleep Aid contains Diphenhydramine, a sedating antihistamine that is designed to help you with short-term sleep problems, including insomnia or when you have a cold or cough that’s keeping you awake. You should take Nytol Night Time Sleep Aid about 30 minutes before bed time and have at least 6 hours duration before you need to get up to be sure you are not still drowsy as you head to work or school. You should not take Nytol Night Time Sleep Aid longer than a few nights in a row but visit your doctor if you are still experiencing sleep problems.