Babies have developmental leaps. These leaps are basically periods when your baby learns new skills or figures out something about the world suddenly. They can cause behavior similar to what a baby does during a growth spurt; such as being cranky/fussy, clingy (wanting to nurse a lot), and crying. Disruption to sleep habits is pretty normal.
The authors of Wonder Weeks found that they tend to happen on a pretty average schedule, give or take a few days. How it starts varies. For some babies it is based on due date and for some it is based on actual delivery date. For premies it can be a little more difficult to figure out.
Once you figure out the start date, it tends to be pretty accurate for most babies though. It goes up to week 75 and 10 leaps. This isn’t necessarily when these major leaps stop, but this is where the book stops. The 10 leaps happen at weeks 5, 8, 12, 19, 26, 37, 46, 55, 64, and 75. Some are bigger than others and may last longer. A common difficult leap is around 9 months, or the 37th week leap. That one seems particularly annoying for many parents.
The book/app also gives some ideas for how to engage your babies new skills. This was particularly helpful for me as it gave me a way to let my son figure things out better and develop his new skills or perceptions of the world. That led to a less angry baby because he got to use what he was figuring out.
This is the link to the site for Wonder Weeks. There is a book and an app. The app can be helpful as it alerts you to stormy periods when you enter your baby’s informations. Neither is really a necessity but they both have lots of great info.
If you do not want to or can’t get the book or app, this site is pretty thorough in explaining the leaps and what to expect during each.