The symptoms of Idiopathic hypersomnia are long lasting while those of Kleine-Levin Syndrome improve or disappear with the onset of adult hood
Idiopathic hypersomnia is a life-long disorder that does not disappear spontaneously. Consequences of this disease are mostly social and professional in nature. Severe idiopathic hypersomnia is a disabling condition that responds poorly to medical treatment and often leads to permanent unemployment.
The symptoms of Kleine-Levin Syndrome appear to be benign and do not have an impact on intellectual or physical function. Symptoms usually improve or disappear with advancing age.