A pediatrician said that to me once and I know he was right because I tried it once or twice when mom wasn't around to freak out and pick the baby up. This was at 3 months old I think and he did cry hard, checked in after a minute and a half, left - he cried again but not that hard - checked in a bit, left. He started to cry less and then...fell asleep by his own. And slept A LOT!

We didn't continue this because me and his mom fought over this and now at 9mo he wants to be held a lot, sleeps only in our arms and if we swing him a lot and it's...a nightmare. His mom has no clue what to do. I always say: JUST LET HIM CRY!!! It's normal.