15 month Dd has always been a great sleeper, 7-7, no problems going down and just playing quietly when she does wake. But the last couple of weeks have been awful. She wakes anywhere between 4 and 6 and stands and girns in her cot, gradually working up to proper crying. We've tried leaving her, but she can keep this up for a full hour and utterly exhausts herself. She will settle if I go through and sit with her, sitting and sucking her thumb, and will sometimes go to sleep again, but usually wakes after I leave. If we take her into our bed she just bounces around, so that's not helping anyone. Any suggestions folks?!