Molecular model of the drug trazodone. This is a serotonin antagonist and reuptake inhibitor used to treat depression and insomnia. It also has potential to treat neurodegenerative diseases such as dementia and Parkinson's disease as trials in mice have shown it halting disease progression. Atoms are represented as spheres and are colour-coded: carbon (light blue), hydrogen (white), nitrogen (dark blue), oxygen (red) and chlorine (green).