Sleepnaked.org is a website promoting people to sleep naked.
The site claims that a person will actually have a better nights sleep if they are in the buff. The theory(I don't see any citations on the site, they claim to have a research page, but i couldn't get to it) is that when nude, you are more relaxed and comfortable, resulting in falling asleep faster and into a deeper and longer sleep.
Sleep Naked also encourages partners to sleep naked together and they will have an increase in intimacy. Studies also show that it showed improved fertility in men, due to the lack of clothing and cooler conditions(just like men that go commando or wear boxers are more fertile than men that wear whitey-tighties).