Exploring sex differences in the longitudinal association between streetlighting and transport walking

Regular physical activity, such as transport walking, is essential for health, yet many adults do not meet recommended physical activity levels. The built environment, particularly streetlighting, plays a critical role in promoting transport walking. However, existing evidence on the relationship between streetlighting and transport walking is largely cross-sectional, with limited longitudinal research exploring potential sex differences. This study aimed to assess the longitudinal association between objectively measured streetlight count and transport walking among mid-to-older-aged adults in Brisbane, Australia, and to explore whether this association varies by sex. Data were from the How Areas in Brisbane Influence HealTh and AcTivity (HABITAT) study, a multilevel cohort study with five waves over nine years (2007-2016). The analytical sample included participants who did not move during the study. Transport walking was self-reported and dichotomized into walkers and non-walkers. Streetlight counts within a 1 km road network buffer around participants' homes were measured alongside transport walking. Generalized linear mixed-effects models were used, adjusting for sociodemographic factors, length of stay, neighbourhood preference, and built environment attributes. Higher streetlight counts were positively associated with transport walking (OR 1.002; 95% CI 1.001, 1.002), and the association remained significant after adjusting for residential density, street connectivity, and land-use mix. No significant sex differences were found. This study provides longitudinal evidence that well-lit environments promote transport walking among mid-to-older-aged adults. This finding can inform urban planning and public health policies aimed at encouraging transport walking to help reduce the risk of chronic disease.