The four - month regression tends to indicate development change as babies become more like adults, at least in relation to sleep patterns. (bounty.com)
In the middle of the 4 month regression right now and hating my life!!!! It IS harder the second time around, because once you're done putting the baby to sleep, you still have to go and interact with the 3.5 year old. (askmoxie.org)
I think we weathered the four month regression okay, but at some point after six months he started waking a ton. (breastfeedingneeds.com)