Yoga has positive effects on mild depression and sleep complaints, even in the absence of drug treatments, and improves symptoms associated with schizophrenia and ADHD in patients on medication, according to a systematic review of the exercise on major clinical psychiatric disorders.Published in the open-access journal, Frontiers in Psychiatry, the review of more than one hundred studies focusing on 16 high-quality controlled studies looked at the effects of yoga on depression, schizophrenia, ADHD, sleep complaints, eating disorders and cognition problems.