My toddler (20 mo) has always perspired a lot, but lately it seems like more. He just seems drenched at night, and it's not that warm in our house. I don't really notice it when he's playing, more when he's nursing to sleep or sleeping. He has had some other health problems- extremely small for his age, allergies to gluten & others, yeast. He also likes to drink lots of water (but I think my older son doesn't drink enough so maybe he's not drinking too much). He had bloodwork done recently and both the thyroid & blood sugar were normal (2 things I've read can cause the sweating). I also read that sleep apnea can cause this but it happens as soon as he starts falling asleep rather than just in deep sleep. Any ideas?