Molly has a strange habit of bashing her head really hard when she is drifting off to sleep. I dont know if it;s to keep her awake. She normally goes to sleep holding a muslin, and will bang it against her head really hard. If I hold her arm down she screams or just starts bangin her head against me or the cot. Do you think this is just a phase she is going through? I'm a bit worried she will hurt herself.