My 9 month old was getting into a decent sleep pattern after a patchy start. Down by 7pm (feed then her dad puts her down). Usually sleeps until 2/3am at which point she wakes and demands a feed - so dad can't put her back down, but then I just co-sleep with her until she wakes usually at 6.30-7.30 (her first nap is usually at 9am for an hour). But the past few days she's been waking at 4.30am, absolutely full of beans, and won't go back to sleep. Any idea why this might be and what I can do about it? 