The Effectiveness of Light Therapy on Circadian Rhythm Factors in Promoting Recovery Among Hospitalized Older Patients

Acute illness and subsequent hospitalization are major sources of stress for older adults. During hospital stays, limitations in mobility and the presence of comorbidities frequently lead to functional decline, which in turn prolongs length of stay and increases the risk of mortality. Light exposure, as a key regulator of circadian rhythms, has been shown to be associated with functional decline in hospitalized older adults. However, previous studies have largely focused on lighting interventions in long-term care facilities, and research conducted in acute care settings remains limited. In addition, traditional light therapy has primarily emphasized illuminance, with less attention paid to circadian action factors (CAF), which capture the impact of specific light spectra on the human circadian system. CAF provides a more precise quantitative index of the potential influence of light exposure on circadian rhythms, thereby improving the accuracy of lighting design. Therefore, this study aims to examine the effectiveness of a CAF-based lighting intervention on functional recovery and quality of life in hospitalized older adults. Wrist-worn devices (Actiwatch) will be used for continuous monitoring of sleep and activity patterns, enabling dynamic assessment of changes in physiological resilience over time. Through longitudinal tracking and integrated analysis of objective data, this project seeks to develop a circadian action factor–based lighting intervention model that can inform more precise and personalized care strategies for older inpatients.