⚠️ There's some concern that anticholinergics (including Benadryl) are associated with Alzheimer's, especially in older people, so I don't take this regularly.
If you look at products like "Advil PM" you'll see that they're combining a pain reliever with a "first generation" H1 antihistamine. For whatever reason, antihistamines sold for allergies are orders of magnitude cheaper than antihistamines sold as sleep aids. I've always been sensitive to Benydryl (let's hope I don't get a bee sting and also need to operate heavy machinery), so I use Diphenhydramine in rare circumstances where I need to sleep and it's not bad to be groggy about 12 hours from taking a pill, e.g. on international red-eye flights or when I'm starting to get sick.