Alpha agonists are non-stimulant drugs and in this case, mostly refer to clonidine and guanfacine. They can be used off-label to treat some of the symptoms of ADHD. Most frequently, they're used for RSD as they're the only medication that is said to help it (about 1/3 of the population will have symptom reduction with either one drug or the other - and the last 1/3 won't see a reduction in RSD symptoms at all). It also can introduce a greater sense of calm and make it easier to sleep. These medications can be used together with stimulants. I typically seen them most commonly prescribed by ADHD specialists who know more about the variety of treatment paths for ADHD, less commonly by GPs.