The prevalence of sleep disorder is about 30% of the population. Common sleep disorders are insomnia, obstructive sleep apnea, narcolepsy, restless legs syndrome, rapid eye movement sleep behavior disorder and parasomnia. These sleep disorders lead various medical and mental complications. However, most sleep disorders are underdiagnosed and not treated appropriately. Sleep medicine is important for treating these sleep disorders and maintaining general healthy conditions. Specialized and comprehensive treatments for sleep disorder are important in sleep medicine.