When the excitement and novelty of having a new brother or sister wears off, the older child may begin to feel painful emotions. The older child can feel left out, second best, and invisible. These painful feelings are very real—real for the child on an emotional level and real in changes that occur in the brain.

Studies using brain scans have shown that feeling left out and being on the outside can activate pain centers in the brain. When a sibling feels left out, the aggressive and impulsive behaviors that can surface are often caused by opioid withdrawal in the brain, the blockage of mood-stabilizing systems, and other brain chemical changes.

Your child is not going to be able to approach you and say, “I think you like my sister more than me, and I am hurting inside.” Your child will more likely communicate hurt feelings by hurting the new sibling, acting defiant, or becoming moody.

To help your child with sibling rivalry, watch him as you interact with the new addition. If you are having a wonderful interaction with your younger child, and the pain of sibling rivalry comes out in the older child’s actions and behaviors, take the initiative to talk to your older child. Remind your older child how much you love him, that no one can take his special seat in your heart, and that you are sorry if you haven’t found a way to show it. You can communicate directly, through puppet play, or through a story.

You can also then make a plan with your older child, so she can let you know when she is feeling left out. For example, your older child can have a special hat to put on when she needs some of your attention or feels left out, or she can bring a family of stuffed animals to you as a reminder. It is also helpful to find some time to spend one-on-one with your older child.

Be sure to let all your children know they are lovable and highly valued.