The story behind a best-selling children's bedtime book

Like most 2-year-olds, Hudson Cowen is not a big fan of nap time.

"That is one of one of the biggest issues for parents: how do I get my child go to sleep," said Hudson's mom Bailey Gaddis. She was eager to try a book that promises to soothe a child into slumber.

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Bailey Gaddis reads to her son Hudson CBS News

It's called "The Rabbit Who Wants to Fall Asleep." The yawns are written into the story. The characters have names like the "Heavy Eyed Owl" and "The Sleepy Snail." There are even notes for when you should read slowly.

It's worked on so many kids that it's become an Amazon best seller in the U.S. and five other countries. That's rare for any book, let alone one that started out self-published with illustrations drawn by a friend.

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Swedish author and behavioral scientist Carl-Johan Ehrlin wrote "The Rabbit Who Wants to Fall Asleep" CBS News

Swedish author and behavioral scientist Carl-Johan Ehrlin says he came up with the idea watching his mom sleep in the car.

"I woke her up and I told her, 'Oh I got this great idea, we've got to write this down.' And we started to look for paper everywhere."

"I went to pre-schools and I asked teachers to read it when they had this group nap time, and they did for a week. They were pretty amazed," Ehrlin continued.

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CBS News' Vinita Nair read the book to her own son CBS News

I was curious if it would work on my son. It didn't happen immediately. But when I read it a second time, he fell asleep.

But it doesn't work on every child.

A quarter of the Amazon reviews are just one star.

Can best-selling bedtime book help children get more sleep?

"Big fat freaking fail," wrote one parent. "My two-year-old hates this book and begs me to not read it," wrote another.

It also goes against the advice of many sleep experts, who say kids need to learn to fall asleep on their own.

But Gaddis says it's been a lifesaver for her family.

"It's really effective and it put me to sleep a few times."

Isn't that the dream of every parent?