and I mean you could ring him out. 3 nights in a row DH and I have had to strip him, towel him down and put him back to bed naked - he's then woken at 4am wondering why he's undressed and put his pj's back on!
He's still in a toddler bed with one of those waterproof mattresses with a breathable velco-ed on layer - could this be the cause?
His twin bro, sleeps in the same type of bed, same mattress, same bedding, doesn't drip a drop, (but does fill his pull up, whereas sweaty DT is "dry" at night).