Until when do naps last? Should I cut down naps that are too long?

Naps decrease with age, and most children outgrow them between ages 3 and 5. The guideline is "the nap isn't interfering with nighttime sleep." Late-afternoon naps or naps over two hours can cause staying up late. Waking them by 3 p.m. and gradually shortening overly long naps often settles the night. For children who develop more slowly, outgrowing naps later is perfectly fine.