To all those night owls, we got something for you. Slow, deep breathing has been shown to result in melatonin production which not only promotes relaxation, but is an essential sleep-inducing hormone. The release of melatonin promotes parasympathetic tone (a calm nervous system) and inhibits sympathetic tone (a stressed nervous system) (5), allowing your body to more easily fall asleep and stay asleep when night time comes around.