Sleep Inn did a survey of 500 guests and found that 1 in 10 hotel guests sleeps in the altogether.
Conducted by WRA Research of Omaha, NE, they found that about 3 times as many men (15% vs 4%) as women sleep nude, since 78% of women prefer to sleep in a nightgown or pajamas.
Sleep Inn said they did the survey so they could best accomodate the needs of their nude guests (inadvertent disturbance by a maid, modesty during a fire alarm, etc.)
Of the men who don't go bare, 34% wear underwear, 28 % wear pajamas, 11% wear gym shorts, 8% wear t-shirts.
I sleep in the nude, too. At home, in a hotel room, staying at a friend's or camping, etc. I have all my life.
The males in my mother's family have done it from childhood, and freeballed as well, for generations.
So, as far as my family is concerned, dick size has nothing to do with it (although I can see where a man who is used to the support of underwear might want to have that support 24 hours a day, and will, therefore, wear something to bed for comfort).
Pecker