4 month sleep regression.

Kimberly

My LO was sleeping 1 6 to 8 hour stretch every night since 1 month old. She is 4 months old today. For the last 2 weeks she is up every couple of hours:( I think some of it is due to switching her to sleeping on a flat surface( she was sleeping in a bouncer/ PAC in play insert thing. When does the 4 month sleep regression start? How long will it last? Not sure if that's what we're going through. I'm so tired!