Our psychiatrists prescribe benadryl at the psychiatric hospital as a PRN (as needed) medication...
It helps for mild anxiety, & insomnia.
I'm 140 lbs, & I've found taking more than 50-75 mgs gives me an undesirable effect. Gives me like an all over body restless legs syndrome effect.... it's awful.
But, If I take say, 50 mgs before bed, or before a stressful event, it can help me to stay calm.
Me, I actually take a cocktail everyday consisting of ashwaganha 900 mgs, suntheanine 400 mgs, 5-htp 100 mgs, & picamilon 150 mgs. Has definitely helped me to stay cool at work.
I only use benadryl when I run out of other things, in a pinch, or as an addition to melatonin, or flexiril before bed.