Very tangentially related, an old trick that often works with small (dog) puppies crying at night when separated from their mother is to put them into their bas

Very tangentially related, an old trick that often works with small (dog) puppies crying at night when separated from their mother is to put them into their basket together with a (warm) hot water bottle and a mechanical alarm clock (those old ones that tick very loud) wrapped in a blanket. In that case it is the combination of (fake) body warmth + (fake) heartbeat that makes them sleep, since we are mammals/animals too, the mechanism for babies is likely similar.