A simple approach to central disorders of hypersomnolence

Abstract Sleep is an essential part of a healthy life which is vital to maintain bodily functions in a well balanced state. Nevertheless, excessive sleepiness can disturb the over all physical and mental health of an individual. Though the day time hypersomnolence is caused by myriad of causes , central disorders of hypersomnolence deserves a special attention. In order to understand abnormal sleep, a thorough understanding about normal sleep is of paramount importance. A normal 8 hour sleep consist of 5-6 cycles of sleep. Each cycle consist of stages of sleep, namely REM, NREM 1, 2 and NREM 3. When evaluating a patient with day time hypersomnolence, its presence must be confirmed with an accepted screening tool such as Epworth sleepiness. A detailed history , examination and laboratory work up is necessary to exclude common medical , neurological and psychiatric illnesses which are common causes of hypersomnolence. This review mainly focus on central causes of hypersomnolence such as insufficient sleep syndrome, narcolepsy type 1 and 2, idiopathic hypersomnolence syndrome and Kleine Levin syndrome. Polysomnogram and multiple sleep latency tests are cornerstone investigations in evaluating these conditions. Despite the central disorders of hypersomnolence are life long chronic illnesses, promising pharmacological as well as non pharmacological therapies are available for the alleviation of troublesome symptoms.