I think they are considered a SIDS risk, espesh lambswool. Flannelette sheets might help though and I am sure a lambswool underlay would be pokay for the bigger kids...I just remember reading somewhere about not using them for little bubbas......also icy fingers and hands don't mean they are cold...the paed told me as long when you touch their breastbone it is warm they are okay...little ones don't feel the cold in the extremities the same way us old farts do!