Men Who Sleep. Anywhere.

We were invited to one of my best friend's sons birthday party in May. She has a few friends and family at her house. It was a great time and I was happy I got to see my friends and their kids.
What I didn't expect to see is at least two men (at different times) napping on a couch in the living room. they just took a nap at a party, at someone elses house. Not only strange but really strange.

This is not the first time I have seen this, I have been at many parties where this has occured. Usually these men don'e even find and out of the way location to snooze in, they just sleep anywhere, even in a crowded room. Obviously these people have never been antiqued.
My sister's husband is like that he can sleep anywhere at any time. He will just sleep sitting up, laying down, at someones house, in his house with company over, whatever.

It is only men who do this. Women never just lay down and nap. I don't even nap in my own home on a lazy Saturday.
What is this phenomenon? Is it narcolepsy that strikes only men of varying ages? I sit laziness? Does the male chromosome carry the sleep anywhere gene?
I am fascinated.