My 27 month old has been potty trained for a few months, and recently has started waking in the night to ask to go for a wee. Before this he had been sleeping through and now we have broken and interrupted nights where he often can't get back to sleep (now up at 5, whereas used to go until 7.) He wears pull ups at night but won't wee in them and hasn't had any accidents. Is this just a phase that will have to last until he's old enough to go to the toilet on his own? He shares a room with his 10 month old brother who is a very light sleeper.