Feeding a baby milk is one of the best ways to get them to sleep. For adults, it's conventional wisdom that a warm cup of milk will help you get to sleep. The "warm" part may just make you feel comfortable inside, physically and emotionally. But scientists have been picking apart milk to see what's in it that promotes sleep. It was once though that the critical ingredient was tryptophan, but that's not all of it.
Milk contains a variety of peptides. Scientists isolated many of these peptides and fed them to mice. One that seems particularly good for promoting sleep is α-casozepine (α-CZP). However, combination of α-CZP and other peptides is even better. Treating the milk protein casein with the digestive enzyme trypsin produces a combination peptide called casein tryptic hydrolysate (CTH) that appears to promote sleep even better than its component parts. Research into isolating the sleep-enhancing chemicals in milk may lead to more natural medications to promote sleep. Or you could just make a cup of hot cocoa, if you are lactose tolerant. Read about this research at the American Chemical Society. -via Real Clear Science