⚠️ There's a pretty serious concern that anticholinergics (including Benadryl) are associated with Alzheimer's, especially in older people, so I don't take this regularly.
(e.g. 50% increase in dementia in people who took some something like every 3 days for 10 years 😳)
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 a half dose of 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 sick and sleep deprived.
Because of the dementia risk, I’m very limited in the circumstances where I’ll take it, but I do think the tradeoffs sometimes make sense (I really struggle with sleep).