The effects of caffeine on drowsiness and reaction time in patients with narcolepsy are unclear. We aimed to assess the effects of caffeine as add-on therapy in narcolepsy patients.
A randomized, double-blind, placebo-control clinical pilot trial was conducted with a parallel, two-arm trial allocation ratio of 1:1. Participants attended two study visits 7 days apart. The drug was administered orally in a single opaque capsule containing 200 mg caffeine/placebo daily in the morning for 1 week. Sleepiness was assessed objectively using infrared reflectance oculography to measure the percentage of long eye closure (LEC%) and subjectively using two sleepiness scales, the Stanford Sleepiness Scale (SSS) and Karolinska Sleepiness Scale (KSS). Parameters were measured at baseline (BL) prior to taking the drug, after taking the first dose (FD), and after 1 week (WD) of daily caffeine.
Sixteen participants with narcolepsy were included. No significant differences between groups in baseline measurements were observed. LEC% was significantly decreased after the FD and WD compared with baseline levels (BL 1.4 ± 2.1 vs. FD 0.06 ± 0.0.6 and WD 0.03 ± 0.04). Significant improvements in alertness were observed using the KSS when comparing BL with FD and WD (6.3 ± 1.6, 4.9 ± 1.7, and 4.7 ± 1.7, respectively; p = 0.01). No changes in reaction time or SSS scores were noted.
Our findings suggest that a small dose of caffeine has positive effects on alertness in patients with narcolepsy. However, larger trials are required to confirm these findings.
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The study was funded by:
1) The Strategic Technologies Program of the National Plan for Sciences and Technology and Innovation in the Kingdom of Saudi Arabia (08-MED511-02).
2) King Abdul-Aziz City for Science and Technology in Riyadh, Saudi Arabia (National Plan for Science and Technology), Grant Student Project (GSP), fund number: GSP -37-47, and the Sleep Disorders Center at KSU University, Riyadh, Saudi Arabia.
Research involving human subjects
This study was approved by the Ethics Committee of the College of Medicine, King Saud University. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
The study was registered at clinical trial.gov (registration number: NCT02832336).
Written informed consent was obtained from all individual participants included in the study.
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Aldosari, M.S., Olaish, A.H., Nashwan, S.Z. et al. The effects of caffeine on drowsiness in patients with narcolepsy: a double-blind randomized controlled pilot study. Sleep Breath 24, 1675–1684 (2020). https://doi.org/10.1007/s11325-020-02065-6