Tough question, when points are in the balance.
As it turns out, my tolerance to antihistamines (benadryl) works in about the same way my tolerance to almost every other OTC and prescription medication works – initially it works in full effect, the next day it works about half that, and the next day about half that, if I am taking the same amount each time. Day one on Benadryl worked fantastic – I was in bed by 10 or so, woke up feeling groggy but not unreasonably so, everything was perfect. Day two I had more trouble going to sleep – it took me until 11:30 to even think about going to bed, but I foolishly thought that I might be tired enough to go to sleep naturally (I was exhausted at 4 and had my normal climb of energy back to peak levels by 10) so I started in on the Benadryl late. Last night? Utter fail. I tried to go to bed at 11. The last time I looked at the clock, it was 2:30 a.m., so I assume I fell asleep relatively soon after that, though I woke up frequently between then and 8:30, when I officially got out of bed.
So I don’t know where that leaves me.