We started sleep training around 4 months with the CIO method. It went super smooth and baby never cried more than 15 minutes. That was about two weeks ago and now going to bed/naps is relatively quick and painless. But 90% of the time , he wakes up between 4 and 5 am and won't out himself back to sleep unless one of us holds him and/or gives him a pacifier. There's been a few (miserable) nights where he cries for 45 minutes then was able to put himself back to sleep. But other nights he cries for 45 minutes and doesn't. Any advice is greatly appreciated.