It's the first day of kindergarten for 5 year-old Sebastian Grau and, his mother admits she's a wreck. 

"I was up about half of the night worried about Sebastian and what our transition would be like today. We've had some rough transitions in previous years," said Heidi Grau, Sebastian's mother.     

Experts say separation anxiety is fairly common among young children and they don't always know what causes it.   

"When a child is anxious they can look really scared, and sometimes act quite irrationally," said Mark Crawford, a Clinical Psychologist.     

That's what happened to Sebastian during his pre-school years.   

"When he leaves me, he holds onto my leg and he won't let go, and the teachers oftentimes have to kind of tackle him," said Joerg Grau, Sebastian's father.   

Meeting the new teacher ahead of time can help ease the transition's can positive words from a parent.    

"Be clear, matter of fact, completely confident even if you have to fake it and sort of go about it as though it's no big deal," said Crawford.