For us it didn't hit till she hit 5 months. It lasted about a week. She went from sleeping 11 hrs straight to waking up every 2 hours. Now she is back to STTN again!
DD would have to be STTN for there to be a wakeful period. Given that she doesn't and is already up frequently at night, I don't know if we'd notice a wakeful period.
just before. luckily it didn't really affect her nighttime sleep, but she refused to nap. ugh. it's getting a little better now, but i lay down and nap with her 1-2 times a day or she's mean all day.
Re: Exactly when did 4 mo wakeful start for your DC?
DD never went through this.
I don't know if DS is going through it or not because he's never really STTN.