Tricyclic antidepressants are used to treat depression. Some may treat other conditions, such as nerve pain, insomnia, and other mental health conditions. Tricyclic antidepressants work by balancing the levels of certain chemicals in your brain, such as serotonin and norepinephrine. Examples include amitriptyline, doxepin (Silenor), and nortriptyline (Pamelor).