Publication Date

4-20-2026

Document Type

Article

Publication Title

IEEE Transactions on Human Machine Systems

DOI

10.1109/THMS.2026.3678582

Abstract

This study aimed to inform nightlight design by analyzing older adults’ subjective feedback and kinematic responses during evening activities. Twenty-seven older adults (mean age: 81 ± 6 years; 14 females) participated in the study. Their preferences for nightlight illuminance and hue were surveyed, and gait and posture adaptations under two illuminance levels were analyzed using spatiotemporal comparisons, principal component analysis (PCA) based analysis, and waveform reconstruction. The results revealed that older adults preferred low illuminance over high illuminance, with warm white and cool colors as the favored choices for evening lighting. Significant differences were observed in spatiotemporal gait variables, particularly stride length, and walking speed, between the two illuminance levels. Differences in illuminance conditions also led to overall and localized posture changes, as demonstrated by the reconstruction of joint angles through PCA-based posture analysis. Additionally, correlations between spatiotemporal gait variables and principal component vectors revealed that PCA provides complementary spatial and temporal information, emphasizing its value alongside traditional gait analysis. These findings emphasize the importance of integrating older adults’ subjective preferences and objective kinematic observations into nightlight design. Nightlight systems that consider illuminance levels, color tones, and biomechanical efficiency can enhance confidence, comfort, and mobility during nighttime activities, contributing to the residential well-being of older adults.

Keywords

Gait, lighting design, older adults, posture, user preference

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Industrial and Systems Engineering

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