The most challenging to diagnose and treat among sleep disorders is idiopathic hypersomnia; a primary disorder of hypersomnolence that is distinguished from narcolepsy by the absence of rapid eye movement (REM) sleep disturbance. This condition is rare. The rarity of idiopathic hypersomnia has precluded any systematic studies or randomized-controlled trials on the subject, and as a result, ability to fully understand and treat this condition is greatly limited. This review covers the major points regarding the clinical features and diagnosis of idiopathic hypersomnia and discusses current evidence supporting the available treatment options for this condition.