DD has always been a great sleeper. STTN much earlier that DS. She would sleep 11 - 12 hrs per night with a 2 - 3 afternoon nap but over the last couple of months (straight after she turned two) this has all changed. She screams and crys when I put her down for afternoon nap, I know she is tired but she will not remain in her cot. Usually after aroung 20 mins I get her up as I am worried that she will wake DS. This makes her very grumpy in the afternoon, she is prone to major tantrums anyway so tiredness makes it worse!! To make things evern harder she has started waking up every night at around 11pm crying and shouting for me. I try and resist going in but eventually do just in case there is a problem. Anyway this then goes on all night, last night I was up with her at least 7 times and did not get to sleep until 2am. Of course then she lay in past 7am this morning as she was exhausted but DS is such an early riser at around 5am so I am only getting around 3 - 4hrs sleep per night and it is now taking it's toll. I really do not understand why the sudden change. Any tips or advise would be very much appreciated.