My daughter is 20 months and has been reliably sleeping through for about six months. Until this week. Monday she woke at 3, wouldn't settle till 5:30. Tuesday 12:30 till 2. Two nights of respite and then tonight - oh, tonight's peachy. She's been awake since midnight, still really unsettled, lots of crying. Given calprofen in case of teeth, given cuddles, left her alone.. still awake. What is this??? God, I actually thought we'd cracked it. Am about to join her in crying.