Can Better Sleep Sharpen Your Eyes? Study Links Insomnia Treatment to Improved Eye Movements
A new study suggests that treating insomnia in older adults may do more than help them sleep, it could improve the way their eyes move during waking hours. Researchers in Japan have found that improvements in sleep quality and daytime sleepiness, achieved through the medication lemborexant, are modestly associated with measurable changes in eye movement patterns.
Published July 4 in Human Psychopharmacology: Clinical and Experimental, the open-label study tracked 31 Japanese adults aged 50 and older with insomnia and preserved cognitive function over 12 weeks. Participants received nightly doses of lemborexant (5 to 10 milligrams), a dual orexin receptor antagonist that blocks the brain’s wake-promoting signals. At baseline, week 4, and week 12, researchers measured both subjective sleep outcomes and objective eye movement metrics using three distinct tasks: free-viewing (watching a naturalistic scene), smooth pursuit (tracking a moving target), and fixation (holding gaze steady on a single point).
What the Researchers Found
Subjective sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI), while daytime sleepiness was measured with the Epworth Sleepiness Scale (ESS). Both showed improvement over the study period. The key finding was that these improvements were linked to changes in how participants moved their eyes.
Specifically, participants whose ESS and PSQI scores improved the most also showed enhanced visual search performance during the free-viewing task. They exhibited increased saccade amplitude (larger jumps between points of interest), longer scanpath length (more ground covered during visual exploration), and higher saccade velocity (faster eye movements). These metrics are commonly associated with more efficient and engaged visual processing.
The smooth pursuit task revealed an additional connection. Greater improvement on the ESS, indicating reduced daytime sleepiness, correlated with better tracking accuracy. Participants made fewer corrective gaze fixations and saccades when following a moving target, suggesting smoother and more precise oculomotor control.
There was also a link between objectively measured total sleep duration, recorded via portable EEG devices worn at home, and saccade duration. Longer sleep was associated with longer-lasting saccades, though the clinical significance of this particular finding is less clear.
Why Eye Movements Matter
Eye movements are increasingly recognized as objective biomarkers of neurocognitive state. They are sensitive to sleep deprivation, fatigue, and neurological conditions, and they can be measured non-invasively with standard eye-tracking equipment. The authors of the study note that while insomnia is known to impair cognitive and brain function, and treatment can improve outcomes, it has been unclear whether these improvements extend to oculomotor function.
If validated in larger, more rigorous trials, eye tracking could offer clinicians a simple, objective tool for monitoring treatment response in patients with insomnia. Instead of relying solely on subjective questionnaires about sleep quality, doctors might one day use a brief eye-tracking session to assess whether a treatment is working.
The study’s findings align with a broader push in psychiatry and neurology toward quantitative, performance-based assessments that complement patient-reported outcomes. Eye tracking is cheap, portable, and non-invasive, making it an attractive candidate for both clinical settings and home monitoring.
Important Caveats
The study has significant limitations that warrant caution. First, it was an open-label, single-arm design with no placebo or control group. Without a comparison arm, it is impossible to separate the direct effects of lemborexant on eye movements from natural recovery, practice effects on the eye-tracking tasks, or placebo responses. The associations reported were also modest in magnitude, meaning eye movement changes did not occur uniformly across all metrics or all participants.
The sample was small (31 participants) and drawn exclusively from a Japanese population, which limits generalizability to other ethnic groups. Participants were also required to have preserved cognitive function, so the findings may not apply to older adults with mild cognitive impairment or dementia, a group that often struggles with both sleep and eye movement abnormalities.
Additionally, two of the study’s co-authors are employees of Eisai, the pharmaceutical company that manufactures lemborexant, though the research was also supported by independent grants from the Japan Agency for Medical Research and Development and the Japan Society for the Promotion of Science.
The Bottom Line
This study provides early, hypothesis-generating evidence that treating insomnia in older adults may produce measurable improvements in eye movement patterns, specifically in visual search efficiency and smooth pursuit accuracy. But the findings are preliminary and modest in scope.
Eye tracking as a clinical tool for insomnia treatment monitoring remains an intriguing possibility rather than an established practice. Larger, randomized, placebo-controlled trials will be needed to confirm whether the observed associations are real, durable, and clinically meaningful.
For now, the study opens a new line of inquiry: if a good night’s sleep can change how we look at the world, perhaps how we look at the world can tell us something about how well we are sleeping.
Source: Miyata S, Kawai K, Iwamoto K, Okada I, Matsuyama N, Shishido E, Miura K, Fujimoto A, Kogo Y, Fujishiro H, Hashimoto R, Ikeda M, Ozaki N. Evaluation of oculomotor function following sleep improvement with lemborexant in older adults with insomnia. Human Psychopharmacology: Clinical and Experimental. 2026;41(4):e70056. doi:10.1002/hup.70056. PMID: 42400307.