CNN: A lack of knowledge on proper dosage, purity, and side effects are reasons parents should not give their child melatonin without a pediatrician’s OK.

“People think melatonin is an herb or supplement, but it’s a hormone,” said Dr. Cora Collette Breuner, a professor in the department of pediatrics at Seattle Children’s Hospital at the University of Washington.

“Does taking it delay puberty? Does it delay the onset of a menstrual period or make it happen sooner? Does it affect somebody that has hormonally mediated disease like thyroid disease? Does it affect something else that is hormonally related, like insulin and diabetes? The verdict is still out on that,” Breuner said.