I work up very refreshed and did not feel sleep or groggy at all. Keep in mind it is an antihistamine and if they bother you this may as well. However if you have any type of seasonal allergy this may hep you sleep soundly and breath easy thereby letting you get some much needed sleep.
Diphenhydramine is used to treat sneezing, runny nose, watery eyes, hives, skin rash, itching, and other cold or allergy symptoms.
Diphenhydramine is also used to treat motion sickness, to induce sleep.