My son is 4 months old and generally sleeps pretty much through the night now. He has the same nappy on from about 9pm till past 8am. He wakes around 6am ish for a feed which I don't change him. He then wakes a couple of hours later so I change him then as he's more awake. Sometimes he doesn't wake after he's 6am wake till around 10am! Is this too long to leave a nappy? Around 12 hours? Does anyone do this ?