I know it's a super common phase for LOs to take 40 minute naps around 4 months of age. LO is now 5 months, and while he is now pretty much falling asleep on his own in his crib for naps (yay!) they are still 40 minutes on the dot. When did you LO start doing longer naps, and did you help them get there or did they outgrow it on their own?

I had thought that once he could put himself to sleep he would be able to transition from one sleep cycle to the next, but it seems like that's not the case...