Sleeping naked is more relaxing and affords you a much better sleep than wearing clothing. It is especially true for some individuals who toss and turn a lot which can cause any clothing to twist and bind up. Many do not realize just how much better they can sleep without clothing as they only know of one way (wearing clothing). For someone doing it the first time it can be very difficult as the sensations of it can be rather overbearing. There is a big difference between the sensations you feel when clothed and those you can experience nude. After you try it a few times you learn to relax and accustomed to the feeling and you start to sleep much better.
As for some of these silly answers here about germs, well, it is very obvious they haven't ever tried it. Reality is if you practice good personal hygiene it is not an issue. Bathing regularly and keeping yourself clean will not result in any more of an issue with germs as when you wear bed clothing. The only difference (which actually supports the idea of sleeping without clothing) is that when you wear clothing to bed you are keeping all those "germs" closer to your body to ferment and such. Washing your sheets regularly (that means at least once a week in place of once a month or year) will also keep the issue of germs to a minimum or make it a non-issue.