Exactly. And different people get different doses and feel lethargic or focused or can go win the world.
I'm guessing the effect of endorphins might depend on the amount of histamine release at the same time (whether you get a big flush or not) so the original article might have some validity.
I'm a more of a morning guy. I'll always remember a girlfriend singing a little ditty "Boys just like to have sex in the morning..." after wards, LOL.
After I turned a certain age, taking DHEA before bed kept me a morning guy. I think it's just my natural cycle.
I forget, but I seem to remember reading a study that men's sexual hormones generally peak in the morning, and woman's peak in the evening.
Speaking of peaking, I almost got a woody watching the final jet fight scene from the movie "Top Gun" just now.
I guess that makes me a Military Brat with an overactive histamine release.