Introduction The understanding of the cells internal clock is of utmost importance inorder to diagnose a disease of sleep.Sleep disordered breathing (SDB) is one of the most common sleep disturbances among children; it represents a spectrum of symptoms from simple habitual snoring (HS) to obstructive sleep apnea (OSA).(1) Chronobiologists Hall, Rosbash, and Young received the 2017 Nobel prize in medicine for their work on the cell’s internal clock. (2) Obstructive sleep apnea (OSA) in children is an prevalent condition that imposes a large array of morbidities, some of which may have longterm implications, well into adulthood.European Respiratory Society (ERS) has defined obstructive SDB as “a syndrome of upper airway dysfunction during sleep, characterized by snoring and/or increased respiratory effort secondary to increased upper airway resistance and pharyngeal collapsibility”. (3,4) The child will show various signs and symptoms which many most often go unnoticed or not considered important, hence its very important to have an proper clinical protocol and management techniques to provide a better adulthood. This review article will help us understand the clinical assessments required in diagnosis of obstructive sleep apnea in pedaitric patients.