A 2006 review covered nineteen studies of the unfortunately named “Extinction” method—the form of “cry it out” in which you leave and do not return—of which seventeen showed improvements in sleep.3 Another fourteen studies used “Graduated Extinction”—where you come in to check on the baby at increasingly lengthy intervals—and all showed improvements. A smaller number of studies covered “Extinction with Parental Presence”—in which you stay in the room but let the child cry—and these also showed positive effects.
