Is this okay for a reception aged child to sleep under? We were thinking of getting one to use as a comfy just on the sofa etc or if he has a tantrum (just started school) but I also read that they can help with night wakings, however not to be used with younger children. I assumed that meant babies and toddlers but would a reception aged child be able to sleep with one? I saw a nice fleecy 3kg one on Amazon...