⚠️ There's a pretty serious concern that anticholinergics (including Benadryl) are associated with dementia, 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 😳 — here’s a meta analysis from Cochrane for people without dementia being at increased risk of dementia or cognitive decline, and another for people with dementia being at increased risk of death.
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).