A study from the University of Australia say that people who have trouble sleeping usually have higher core body temperatures. Which means, sleeping without clothes would probably result in better and deeper sleeper. It'll be faster and more effective.
With your body temperature kept low during sleep, you'll be able to increase the amount of anti-aging and growth hormones including melatonin. If the body is too hot, the body will not be able to naturally cool itself to allow the release of these hormones. Melatonin is vital in the body's regeneration and restoration.
According to studies, a good night's sleep can help reduce belly fat, which also helps to decrease the amount of cortisol - the hormone responsible for stress.
According to a profession of physiology at the University of Nottingham, sleeping naked has been linked to better "brown fat" levels in the body. Body temperatures tend to be lower and are said to slowly increase their brown fat levels making it work harder to keep their bodies warm.
You'd think sleeping naked would be bad for your gentle parts. Like what if something crawled on them?? But actually, sleeping naked can help keep these bacteria at bay, because vaginal bacteria thrive in moist and warm environments. Sleeping naked has also been found to increase fertility in men for the lower temperatures in which sperm thrive in.
Sleeping naked has also been proven to increase levels of oxytocin. According to Dr. Fran Walfish, when you and your partner both sleep naked, the skin-to-skin contact will release the feel good hormone.