Dr Alison Bentley advises:
Unfortunately, you’ll have to battle it out in the middle of the night. When your baby wakes, don't pick her up and insist that she lies down. She won’t like this because she doesn't know how to fall asleep on her own any more. It makes her very anxious and it becomes easier for her to stay up for a few hours until she feels sleepy again. But she needs to sleep.
The best way is to insist she lies down, stay with her and calm her down. Once she is calm, stop touching her and wait for her to fall asleep. She will most likely act like a true insomniac – tossing and turning – but just support her with your voice. Once she is asleep you can go back to your bedroom.
After 3 to 4 days she should be sleeping better and the whole problem should resolve within a week.