Who teaches what
Nidra leads the body scan — toe to crown, calm and level and unhurried — which is yoga nidra, done properly and slowly. Baba Bear breathes in for four and hums on the way out, because a long hum forces a long exhale, and the long exhale is the settling half of the breath. Chief Mindfulness teaches noticing one small thing at a time, straight out of the book Tardy does Mindfulness — raisin and all.
What sleep meditation for kids should never do
The category has a problem, and it is worth saying plainly: a great deal of sleep meditation for kids is invented. Somebody wrote something that sounds soothing, gave it a name with the word breathing in it, and recorded it in a soft voice. It may do no harm, but it is not a technique, and a child who practises it is practising nothing.
Everything here has a source. The body scan is yoga nidra, which is old and studied. The long hum out is a lengthened exhale, which is the settling half of the breath. The noticing came out of a book that is in print, with a raisin in it. Where we could not find a real technique for something, we left the gap rather than filling it — the same rule that governs every fact in this world, and the reason none of the animal facts here are made up either.
Meditation, not instruction
A child cannot be told to relax any more than they can be told to fall asleep — the telling creates the trying, and the trying is the problem. So these films never instruct. They show someone else breathing slowly, noticing slowly, going quiet slowly, and a child lying in the dark does what children do best, which is join in without being asked.