(Benadryl, Nytol, Sominex, Unisom, Bayer PM, Excedrin PM)
What are they? All of these products have an antihistamine (the drug that helps fight allergies and often makes you groggy) as their sleep-inducing ingredient.
How long can you take them? Ten to 14 days.
Do they work? Yes—sort of. They generally lose effectiveness after two or three days. In addition, many people don't get "good sleep" with antihistamines, possibly because the period of time spent in REM sleep, considered essential for memory and learning, can be altered. Side effects may include next-day grogginess, dizziness, dry mouth, headache, and trouble with coordination. Doctors don't usually recommend their use as sleep aids.