Our 21month DS has started to wake up in the middle of the night, wide awake in his cot, wanting entertainment. He resists all our attempts to get him back to sleep - he hates coming to our bed but will go quiet when we shhhh him, only to compain loudly when we stop or walk out. Eventually he will exhaust himself to such an extent that he will sleep again. This can take up to 3 hours! All of this will make everybody grumpy the following day and thge cycle goes on. Occasionally he will sleep all the night through, if only to prove that he can do it if he wants to. Help!