Evaluation of Oculomotor Function Following Sleep Improvement With Lemborexant in Older Adults With Insomnia

Insomnia impairs cognitive and brain function, and its treatment improves outcomes. Eye movements are objective biomarkers of neurocognitive state and are sensitive to sleep loss, but whether treatment improves oculomotor function remains unclear. We examined associations between sleep improvement and eye movement changes after hypnotic intervention.

In this open-label, single-arm study, 31 Japanese adults aged ≥ 50 years with insomnia and preserved cognition received nightly lemborexant (5-10 mg) and were assessed at baseline, week 4, and week 12. Eye movements were measured using free-viewing, smooth pursuit, and fixation tasks. Objective sleep was assessed with a portable electroencephalogram, and subjective sleep and sleepiness with the Pittsburgh Sleep Quality Index (PSQI) and Epworth Sleepiness Scale (ESS). Associations were analyzed using linear mixed-effects models.

Improvements in ESS and PSQI scores were associated with enhanced visual search performance in the free-viewing task, including increased saccade amplitude, scanpath length, and velocity. ESS improvement correlated with better tracking accuracy during smooth pursuit, reflected by fewer gaze fixations and saccades. Longer total sleep duration was associated with increased saccade duration.

Selected eye movement metrics were modestly associated with improvements in subjective sleep symptoms following hypnotic treatment in older adults with insomnia.