Study objectives: To measure the effect of nocturnal sodium oxybate administration on sleep architecture in patients with narcolepsy.
Design: Open-label study.
Setting: Four accredited sleep clinics.
Participants: 25 adult patients with narcolepsy-cataplexy.
Interventions: Patients were weaned from previously used anticataplectic medications and administered increasing nightly doses of sodium oxybate over a 10-week period: 4.5 g for 4 weeks, 6 g for 2 weeks, 7.5 g for 2 weeks, and 9 g for 2 weeks. The effect of sodium oxybate was measured using nocturnal polysomnograms, the Epworth Sleepiness Scale, the Maintenance of Wakefulness Test, and a narcolepsy symptoms questionnaire.
Results: The nightly administration of sodium oxybate produced dose-related increases in slow-wave sleep and delta power, rapid eye movement sleep increased initially and then decreased in a dose-related manner, nocturnal awakenings decreased, and daytime sleep latency increased. Significant improvements in daytime symptoms were measured by the Maintenance of Wakefulness Test, the Epworth Sleepiness Scale, and the narcolepsy symptom questionnaire.
Conclusions: Nocturnal administration of sodium oxybate in patients with narcolepsy produces significant improvements in sleep architecture, which coincide with significant improvements in daytime functioning.