Looking for a book about kids who wake up on a spaceship travelling across the galaxy?

i read it ages ago, prob in the 90s, its a very similar story to earthseed. they wake up on a ship in coffin like things in a playroom and have memories of playing there. there is a big smashed globe on the ceiling. they have flashes of their past lives called rem cycles i think or something, enormous ship, kind of a gene bank thing? they fly through something called colour space. what was the title?