A sleep doctor is a medical doctor specialized in diagnosis & treatment of sleep-related disorders as such as Obstructive Sleep Apnea (OSA). There are three types of sleep apnea namely obstructive (OSA), central (CSA), and a mixture of the two called mixed sleep apnea. Risk factors for OSA result in overweight, allergies, a small airway, and enlarged tonsils. Sleep doctor also treats other sleep-related disorders namely insomnia, Restless legs syndrome, Periodic leg movement disorder, Narcolepsy, Circadian rhythm disorder and a few more