Sleep from three to twelve months

This is the stretch where sleep starts to have a shape, and also where it repeatedly loses it again. Night stretches lengthen, daytime naps consolidate into fewer and longer ones, and then something disrupts all of it: a developmental leap, teeth, illness, or a move. Regression is a misleading word for what is usually a temporary interruption of an underlying trend. A predictable wind-down helps more than any single technique, and different families land on very different arrangements, which is fine.