PURPOSE OF REVIEW: This review examines the most common circadian rhythm disorder in adolescents, delayed sleep phase disorder. It explores the etiology, prevalence, clinical features, diagnostic tools and criteria, and treatment options to identify sleep disorders early in the course. This is important to help improve youths in terms of education and quality of life. RECENT FINDINGS: Recent studies indicate that delayed sleep wake phase disorder has a range of prevalence between 1% and 16%. It is often associated with neurodevelopmental disorders (i.e. attention deficit hyperactivity disorder and autism spectrum disorder) as well as psychopathology (i.e. substance use, anxiety, and depression). It can present with a myriad of symptoms, such as insomnia, restless sleep, and poor daytime cognitive function, often seen in pediatric practice. Important diagnostic measures incorporate history-taking, sleep logs, actigraphy (i.e. Apple watches) and measurement of dim light melatonin onset. Treatments include improved sleep hygiene, chronotherapy, exogenous melatonin administration, and bright light therapy. SUMMARY: There are many environmental and genetic factors that can predispose an individual to circadian rhythm disorders. Delayed sleep phase disorder has detrimental effects on overall health, cognition, and behavior. It is important to screen for this disorder in routine pediatric clinic visits. The goal of early intervention is to prevent health and behavioral complications and treat adolescents using a multimodal approach, especially those with affective/neurodevelopmental conditions, who are prone to having delayed sleep wake phase disorder.