This study evaluated the effects of gac fruit oil supplementation on visual health, sleep quality, depressive symptoms, cognitive function, and brain imaging parameters in adults with sleep disturbance. Participants aged 40 to 65 years were recruited and received gac fruit oil capsules for 30 days. The supplementation protocol consisted of two capsules in the morning and two capsules in the evening each day. Assessments were performed before and after the intervention, including macular pigment measurement, ocular surface disease evaluation, tear film analysis, contrast sensitivity testing, accommodative microfluctuation analysis, optical coherence tomography, the Pittsburgh Sleep Quality Index, a depression scale, the Mini-Mental State Examination, and brain magnetic resonance imaging. The study aimed to explore whether 30 days of gac fruit oil supplementation was associated with changes in visual function, sleep quality, mood-related measures, cognitive function, and brain imaging findings.