Very true! Benadryl was primarily intended for use as an allergy medication, though it’s common for meds to get repurposed like this if they have other effects. Histamine in your brain is important for maintaining wakefulness. Non-drowsy allergy medications avoid this by making sure they can’t get past the blood brain barrier.

All those pm meds are just branding. Unless you’re also in pain or have a fever and too lazy to take two pills or something, there’s no real benefit. Just a glance at amazon shows the unit price of tylenol pm vs the same dose of generic benadryl (diphenhydramine) is 12x more! There’s multiple meds like this in the over the counter section, always read what the actual active ingredients are, not just the branding. I’m particularly annoyed by all the combination products that wrap tylenol/acetaminophen in them, or an NSAID (ibuprofen, naproxen), as it could be easy to accidentally overdose those if you were also taking them separately or a very similar med.