If she is 4... does that mean she will be starting school next week? If so... use this as the "springboard" to her becoming a big girl. Tell her she needs to start sleeping in her room this weekend so she can get used to it so she will sleep good in her room on school nights. You can compromise by allowing her to sleep in a sleeping bag on her floor near the door tonight, then she will move her sleeping bag closer to her bed tomorrow night, and then Sunday she will sleep in her sleeping bag on top her bed. Monday night will be in the bed without the sleeping bag. Tell her the complete plan up front and tell her it is not an option. As her mother, you know how important a good night sleep is to a child and it is your job to help her to learn to sleep on her own.