Central hypersomnias are characterized by severe excessive daytime sleepiness despite long sleep periods (\>10 hours/night) and the absence of nocturnal sleep pathology. They preferentially affect young adults, may result in loss of employment, and can lead to motor vehicle accidents (1). Despite these health, safety, and quality of life consequences, there are no FDA-approved therapies for several forms of central hypersomnia, including idiopathic hypersomnia (IH). Currently, IH is treated using therapies approved for narcolepsy, despite a lack of clinical trial data and a consensus that treatment response is poor (2). Treatments include traditional psychostimulants (e.g., amphetamine derivatives) as well as wake-promoting agents with unknown mechanisms of action such as modafinil and sodium oxybate. In addition to side effects including high abuse potential, tachycardia, and altered mental status, treatments are often ineffective and substantial residual sleepiness frequently persists despite poly-therapy.

The investigators hypothesize that pathology in the GABA neurotransmitter system, the brain's major inhibitory system, underlies these central hypersomnias. Currently, there are no hypersomnia therapies that are GABA-antagonists. However, the macrolide antibiotic clarithromycin has been shown to have GABA-modulating properties, resulting in the development of insomnia or mania in a subset of patients. Clarithromycin is therefore a potentially viable, promising therapeutic agent for hypersomnia related to positive modulation of the GABAA receptor. Open-label use of clarithromycin in six hypersomnia patients with known (n = 4) or suspected (n = 2) excess GABAA potentiation resulted in marked improvements in vigilance, as measured on the psychomotor vigilance task (PVT) (unpublished data). The investigators therefore propose a pilot, crossover trial comparing clarithromycin to placebo for the treatment of hypersomnia in patients with excess GABAA potentiation. The primary endpoint will be a decrease in PVT reaction time. Secondary endpoints will include a decrease in PVT lapses and changes in Epworth, Stanford, and FOSQ sleep scales. Successful results from this trial would provide early evidence for a more rational and efficacious treatment for hypersomnia that could avoid the potential abuse, toxicities, and treatment failures associated with traditional treatments.

This will be a pilot crossover trial of clarithromycin and placebo to treat central hypersomnia. Subjects who are untreated for hypersomnia or who experience persistent symptoms despite traditional therapies will be eligible. Subjects who are on medication for hypersomnia at the beginning of the study will be asked to maintain stable doses of these medications for one month before and throughout the study period. Twenty subjects will be assessed at baseline and one and two weeks after being on each study drug (clarithromycin 500 mg bid and matched placebo bid). After two weeks on study drug, they will undergo a one week washout period, then change to the other study drug for an additional two weeks. Patients will be randomized to order of presentation of study drugs such that ten subjects will be randomized to each group. Random sequence generation will be performed our pharmacy. All study investigators and subjects will remain blinded to group assignment.