Background <p>Insomnia, which is a common complaint among older adults, is associated with cognitive deterioration and a lower quality of life. Kami Guibi-tang (KGT), traditional Eastern herbal medicine, is known to be beneficial for sleep and cognitive health. However, its efficacy and safety in treating older adults with insomnia needs to be clearly established. This study evaluated the safety and efficacy of KGT in enhancing sleep quality and cognitive function of older adults with insomnia.</p> Methods <p>A total of 34 elderly participants randomly received either KGT or placebo granules for 12&#xa0;weeks. The primary endpoint was the change in Pittsburgh Sleep Quality Index (PSQI-K) score, while the secondary endpoints included changes in the Insomnia Severity Index-Korean (ISI-K), Seoul Neuropsychological Screening Battery-Dementia, Short-Form 36 Health Survey, and Short-Form Geriatric Depression Scale (S-GDS). Safety assessments included monitoring of blood pressure, pulse rate, body temperature, blood tests, electrocardiograms, and documentation of adverse events.</p> Results <p>While both KGT as well as the placebo groups demonstrated significant improvements in PSQI-K and ISI-K, the KGT group indicated greater cognitive benefits, especially in the domains associated with memory and executive processing. An improvement in the S-GDS was also observed in the KGT group. No side effects were linked to KGT.</p> Conclusions <p>KGT can be considered as a safe and potentially effective therapeutic option for enhancing sleep and cognitive function among older adults suffering from insomnia. The added improvements shown by the KGT group in cognitive function and depressive symptoms indicate that KGT might provide broader benefits in addition to sleep enhancement.</p> Trial registration <p><a href="https://cris.nih.go.kr">https://cris.nih.go.kr</a> Registration Number: KCT0008391 (April 27, 2023).</p>