We've been on that roller coaster since 20 months (so its been 8 months). Its like a mad cycle. Some days she will try to power on and won't nap, gets to 5pm and I have to physically keep her awake till a decent hour (or will completely pass out and then have to make her stay asleep all night), then she is awake at the crack of dawn and the next day requires a nap to make up for it. Other days wont nap at all and be fine. Others will nap and then be up till 10 oclock that night. It literally has driven me bonkers some weeks. I'm hoping by the time she is 3 she will have worked it out.