Kleine-Levin Syndrome (KLS) is a rare but interesting dyssomnia that affects mostly teenagers. Most patients are boys. The symptoms are excessive sleeping (periodic hypersomnia) and, when the person is awake, characteristics of the manic phase of bipolar patients. These include compulsive eating and hypersexuality.
The sleeping periods last about 18 hours and are followed by short-term insomnia. The sleep patterns are all screwed up. During the long sleep periods, little deep sleep is experienced. Patients have frequent microarousals.
Mental functions are also diminished in the sense that the patient has less ability to focus and concentrate and has poor memory. Most patients have lower speech propensity, often remaining quiet or responding to queries and stimuli with childish language. Partial amnesia occurs in many cases.
The excessive eating, called formally megaphagia, polyphagia, or hyperphagia, often causes weight gain during the attacks. The hypersexuality shows up as excessive masturbation, obscene language, and indecent exposure.
Between episodes, the patients sometimes exhibit signs of clinical depression. This is one more way KLS looks like bi-polar syndrome.
Some scientists suspect KLS is an autoimmune syndrome or related to one. Although it is poorly understood, human leukocyte antigen (HLA) is tied to autoimmune diseases, and also to the sleep disorder narcolepsy. HLA allele frequency is higher in people with KLS.
An unknown virus is also suspected as the cause, because the patient appears to have a cold or influenza before onset of KLS in many cases. Analysis of KLS brains shows lesions thought to indicate viral infection.
KLS runs in families and occurs more often in Jewish populations suggesting a genetic component in its etiology.
It’s hard to tell is someone has KLS from lab tests. Even with advanced modern imaging systems, the brain looks the same, and there are no biomarkers in the blood or cerebrospinal fluid. Doctors have to rely on reports from the patient and his or her family. This is a "clinical" diagnosis.
As suddenly and without warning as KLS shows up, it disappears. It always disappears after a few years at most. Nobody knows why.
In any case, KLS is very rare, although this is partly due to underdiagnosis and the belief that the symptoms are normal teenage characteristics taken to extremes.
A rare condition in which teens sleep for long periods is sometimes called Sleeping Beauty Syndrome. Whether these cases are Kleine-Levin syndrome is not clear
One way of looking at Kleine–Levin syndrome is that is a form of idiopathic hypersomnia, on the same spectrum as hypersomnia rather than a separate illness. Both have unknown causes and both leave the sufferer with sleep inertia upon awakening after long sleeps. The personality traits of patients are similar: irritability, depression, apathy, inattention and poor concentration.
Both have no biomarkers and are diagnosed from behavioral reports.
The manic aspects of KLS are not present in most people with idiopathic hypersomnia, but it might be that when adolescent boys get hypersomnia, their hormones and general level of brain development leads to these symptoms.
KLS is often not treated because there are no great treatments. Amphetamines and lithium have some efficacy but antiepileptics don’t. Some doctors may prescribe drugs for symptom control, but the results will probably only mitigate the KLS, not alleviate it. Patients and their families are usually told to wait the disease out.