My DD aged 2.9 has started to wake up during the night, its not every night, but is usually between 1am and 2pm and then she can be awake for up to 2 hours. Have tried resettling her and then just leaving her to cry, have tried sitting with her until she falls back to sleep, but nothing works, its like she is just not tired and only goes back to sleep when she is ready. Not sure what else to try now, any help? Thanks