but I will chime in anyway.

Benadryl (diphenhydramine) is related to the phenothiazine family of antipsychotics. Its tranquilizer potential is much less.
It however is a strong anticholinergic (causes dry mouth, dry eyes and will dry out membranes and perhaps make sinus worse over time). It also works on some receptors in the brain--you can read about it here:
http://en.wikipedia.org/wiki/Diphenhydramine

Children often have paradoxical reactions to it...leading to agitation etc. Typically they outgrow that. Many drugs have paradoxical effects in children since their brains are not developed. Some adults retain that reaction.

As people age, Benadryl is in the "do not use" category, because anticholinergics are not handled well in the elderly.
It can cause dementia-like confusion.

Benadryl is also used for some dystonias, especially those caused by drugs like Risperdal and Geodon.

It remains a potent antihistamine and is lipophilic and crosses the blood brain barrier to cause sedation. It blocks the neurotransmitter effects of histamine in the brain. Many people do not know that histamine is a neurotransmitter that is thought to be the "releaser" for other neurotransmitters. This is why it is so complex and hard on some people.

Many products for cough/cold/sleep now have doxylamine in them
instead of other antihistamines. Unisom and Nyquil are examples.

I've used Benadryl for years...but had to give it up. My doctor kept at me, and I did notice the drying effects on my eyes and nose were becoming significant. I've switched to 1/2 dose Zyrtec (5mg). I can't tolerate the full 10mg dose of that either, but it is working for me at 5mg as an antihistamine.
It does nothing for me for sleeping...in fact 10mg keeps me awake. Zyrtec is related to Atarax, with less sedation. It is chemically similar to Atarax.