Just talking to a friend. Is it true that you’re not allowed to sleep in the nude aboard a naval vessel (at least in the USN)?
Darn I dont know if that’s true but I’m gonna go on a porn search now. Thank you very much dude, I was just off going to sleep. Darn.
Hmm… I’m not sure if your research method is a scientifically sound one for answering the OP’s question.
I’ve never served in the Navy, but I’ve heard that on submarines at least, they use “hot cots,” meaning that the same bed is used by different people on different shifts. In that case, at least, I can see not wanting people to sleep in the nude. And even on a larger vessel that might not do this, there might be an expectation that you could be called to your duty station at any time.
According to my father it was not a all unusual to be called to your duty station in the middle of your sleep shift and sailors (including) him frequently reported to duty naked in those situtations. Of course this was during Vietnam before women were allowed sea duty. I’ve also seen WWII photos with nude sailors manning anti-aircraft guns.
That gives a whole new meaning to “Man Your Battle Stations”. 
There is a phrase in the military that you want every swinging dick in an emergency. But, not quite that literally. 
Given those circumstances, a rule requiring sleeping in your boxers makes sense.
It would make sense in regard to being in a warzone.
I wont believe it if I dont see some well documented and graphic pics of this. Alas my research proved fruitless and left me hanging.
…
Never mind, I’ll just leave the low-hanging fruit alone.
I was in the Navy from 2001 to 2005.
I don’t think there’s any actual rule against sleeping nude, but it would be frowned upon, and only partly because of needing to get dressed quickly if general quarters was called.
The main reason is that there just isn’t a lot of privacy in berthings, and anyone who tried sleeping nude would quickly become known as “that weirdo who always has his junk hanging out.”
I would refer you to this book: http://www.amazon.com/At-Ease-Navy-Men-World/dp/0810948052 which, while not entirely of prurient homoerotic interest, fills that role quite nicely. It has the naked gunner picture mentioned upthread.
I did a little reading because I thought it could be a gender thing, but it appears that women are still not allowed to work full time on submarines due to needing separate living quarters (why couldn’t they staff the whole thing with females? I don’t fuckin’ know).
Anyway, it seems the question has already been answered. But I thought I’d let you know it’s definitely not a gender thing 
Holy shit, a whole submarine filled to the brim with overheated females…I need to inspect that.
<obligatory seamen/semen pun>
Does it have pictures of a submarine run entirely by naked women?
eta: well, not of the submarine itself… you know what I mean
Wow, a phallic symbol made of hard steel cruising in hot waters, gorged with hot steamy females…
Well, the first problem is that the first crew wouldn’t have a clue about what to do. You serve for about a year on an active duty submarine before you learn everything basic that you need to know about it. That’s when they give you the pretty little fishes badge.
Set the females up to cycle through a “slow attack” sub, where there is enough space to have a small number of females through at a time. Once you have enough females trained to crew a fast attack, then you can have a female crewed sub.
Submariner from 1982 - 1987. Fast attack only. Unless things have changed since then, there’s no such thing as a “slow attack” sub. Ballistic missile subs were called “boomers,” and we in the fast attack classes such as the Sturgeon class used to call the (larger) Los Angeles class boats “slow approach.” But that was really just a sailor joke.
Only on rare occasions did I find myself “hot-racking”; that said, I never saw anyone walking around (or emerging from their rack) nude. Wearing one’s dosimeter would have been problematic, anyway. I was never instructed that nude sleeping was forbidden, but it never occurred to me to ask, either.