allowing infants to “cry it out” DR. HOLT IS A DICK And according to Grok…The practice of allowing infants to “cry it out” (CIO) without picking them up to encourage independent sleep—often called sleep training or extinction—originated in the late 19th century. The earliest known advocate was Luther Emmett Holt, an American pediatrician. Although Dr. … Continue reading DR. HOLT IS A DICK