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As he pulls up her colorful blankets and tucks his daughter Raegan in for bed, Retired Army 1st Sgt. Seth Kastle knows that tonight “bedtime” will be a little different.

Tonight, Seth will read his daughters "Why Is Dad So Mad?" — a book he wrote about himself.

Kastle served for 16 years in the Army Reserve, and was deployed to Qatar, Afghanistan, and Iraq. When he returned home to his wife and kids in Wakeeney, Kansas, he struggled with Post Traumatic Stress Disorder (PTSD) and had a hard time explaining it to his kids.

"I struggle with anger. That’s probably my main symptom. I also have some issues that go with my memory," Kastle said. "There's mornings that you go into the bathroom and you look at the cup that holds your toothbrushes, and you just stare at it because you don't know which one is yours."

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Kastle searched for resources to explain his PTSD to his children, but found the options lacking. So, he wrote a book and started a Kickstarter campaign to raise the funds to hire an illustrator and get the book published. The campaign met its $3,000 goal in just eight hours, and eventually swelled to more than $6,000.

"In my book I talk about the fire inside dad's chest. To me, that's what it feels like," Kastle said.

In "Why Is Dad So Mad?" a family of lions — representing the Kastle family — is battling to overcome the father lion’s PTSD. In the book’s colorful pages, the father lion is shown with a raging fire inside his chest. That image, and its message, made an impact on Kastle’s 6-year-old daughter, Raegan.

"No matter what, when they're mad or sad at you, they still love you," explained Raegan, admiring her father’s book in her playroom. "There’s always a fire in his heart, but no matter what, I know there’s love."

Kastle — with help from illustrator Karissa Gonzalez-Othon and designer Lyndsey Dugan — wrote his book for his family, but he hopes that it will serve as a resource for other military families as well.

"I hope that other military families have a chance to sit down and explain to their kids that it’s not always going to be easy, but they’ll get through it," Kastle said.

Kastle is already working on his next book for military mothers with PTSD, and is using the extra funds from his Kickstarter campaign to finance it.

As Kastle turned the final page of his bedtime story book, his daughter Raegan wrapped her arm around her father and kissed him on the cheek. "I like this book. I’m really proud you did it," she said.

The book is available now at www.kastlebooks.com.