The primary objective is to evaluate the therapeutic effect of excessive daytime sleepiness associated with narcolepsy. Both of the subjective and objective sleepiness of the patients were assessed in the experiment by repeat measures.

Inclusion Criteria:

• Polysomnographic findings of shortened sleep latency less than 5 minutes average of Multiple Sleep Latency Test, and two or more SOREM should be fulfilled.
• Age of 12 y/o to 55 y/o.
• The liver and kidney functions are within normal limits.
• Meeting the strict criteria of narcolepsy described above.
• Wash out any medications which might enhance wakefulness or affect nocturnal sleep two weeks prior to the experiments.
• Willingness to comply with the protocol and signed the written Informed Consent.

Exclusion Criteria:

• Patients whose hypersomnia was caused by severely sleep deprived, phase delayed, or suspected long sleeper.
• Patients with concomitant neurological disorder and psychiatric disorders.
• Patients with sleep-related breathing disorders whose apnea/hypopnea index (AHI) was 5 pauses per hour above.
• Patients with Restless Leg Syndrome & Periodic Limbs Movements whose index was more than 5 per hour.
• Patients who are pregnant or breast-feeding.