The Sleeping Beauty Syndrome: Unraveling the Mystery of Kleine-Levin Syndrome

Kleine–Levin Syndrome (KLS) is a rare relapsing-remitting sleep disorder characterized by recurrent episodes of hypersomnia, cognitive and behavioral disturbances, hyperphagia, and, in some cases, hypersexuality. These episodes typically last several days to weeks and recur intermittently over months or years, leading to profound impairment in education, work, and social life. Although the syndrome was first described over a century ago, its etiology and pathophysiology remain poorly understood. This review summarizes current evidence on epidemiology, clinical presentation, diagnostic challenges, underlying mechanisms, and available management strategies. Evidence from neuroimaging and neurochemical studies points toward hypothalamic and thalamic dysfunction, alongside possible autoimmune and genetic predispositions. Diagnosis remains clinical and one of exclusion, as no validated biomarkers exist. Current treatment options are largely symptomatic; stimulants may improve alertness, mood stabilizers can reduce episode frequency, and immunotherapies remain under investigation. The natural history is generally favorable, with eventual remission in most patients, but long-term cognitive and psychosocial sequelae are increasingly recognized. Greater awareness, standardized diagnostic pathways, and international multicenter research are urgently needed to improve outcomes in this enigmatic disorder.