The phrase "to calm down" means to become less agitated, upset or excited. It is an idiomatic expression that refers to reducing one's emotional state from a heightened level to a more relaxed and composed condition.
This simple tool can help calm you down when experiencing uncomfortable symptoms due to a racing mind and tense body. (wellness-media.com)
Music can get us excited and motivated, remind us of fond memories, help calm us down when we're stressed, or even help us wind down for sleep. (lullabyearth.com)
When you first load your eyes the intro video is a colourful attack on your eyes and it doesn't really calm down after that. (thisisxbox.com)