Food Dye and it's effects on children

I wouldn't have believed it if I hadn't witnessed this personally.  One of my granddaughters has had a complete change of behavior since going dye-free.  She is only 5 years old and was diagnosed with a sleep disorder, separation anxiety, general anxiety... what a remarkable turn around.  And I salute my daughter for trying the dye-free option.  It is not easy!!  Why do we still put this stuff in food?  I am just wondering...