Hello and hope you are doing well.
Benadryl is an antihistamine and though its side effect is drowsiness, it may not help for insomnia. Either way to most of the antihistamines, people develop tolerance, that is they stop working very effectively with time. So, try to develop good sleep hygiene. Sleep and get up at the same time every day, avoid smoking, alcoholic and caffeinated beverages and exercise regularly. And consult a sleep specialist for the insomnia, he may help rule out sleep disorders.
Hope this helped and do keep us posted.
you will exeed from 5 to 50 you shuld ask doctor first