Well, think it's working! did it again last night, and not a pepp out of him until 6.30am, then lots of intermittent noises until we woke him for his breakfast at 0700 - he was asleep at that point, so it was just noise in his sleep and resettling noises. Will persist again tonight just to make sure, but looks like it has worked (fingers crossed!) - thanks for your help!
