C.D.
My son did this til he was 13 months old. Now he is better but we have some bad nights. We used a milder version of ferber method because we use a pacifier. It took about a week total but he wakes up less often. Let him cry and every 5 min just open the door and say shhhh or in my case I just gave him his pacifier back and he continued to cry but less time each night... Hope that helps a bit.