The phrase "nap transition" refers to the process of changing from taking multiple short naps throughout the day to having one longer nap or no nap at all. It typically happens as a child grows and their sleep patterns develop. Full definition
In our last post, we'll talk about the timing of nap transitions. (pearltrees.com)
You could see that your baby refuses the second nap which is often assumed to be a usual nap transition and the child is now ready for one nap per day. (shrewdmommy.com)
As I touched on briefly, 3 - 5 months is the average age that the 4 - 3 nap transition occurs. (weebeedreaming.com)