L.E.
i don't know how absorbent they are, but they have the overnight underwear for older kids... ??
also, have you tried starting to potty train? we used to just take him from the bed and make him go sometimes if he woke up at night and going potty just before bed is a Must!!!
AND no liquids for 1 hr before bed. that should help.... we also got pads for the bed so we didn't have to do a sheet change in the middle of the night.
-L.