I should have updated. She DID go back to sleep!! I snuck out at 6.20 with her grumbling, whining, crying, to warm up in my bed for 10 mins. At 6.40 I remember thinking I will just wait til it sounds a bit more urgent. Next thing, its 8.20 and i can hear her happily saying 'mama? Dada?' So grateful she gave us that 1.5hrs sleep...