Translational Light-Based Intervention Strategies for Improving Sleep and Circadian Health in Early Childhood - PROJECT SUMMARY/ABSTRACT Evening sleep problems are prevalent in early childhood and increase the risk for poor behavioral and health outcomes. Sleep is regulated in part by the timing of the circadian clock. Light is the primary zeitgeber (time cue) of the circadian system, and evening light exposure can suppress production of the sleep-promoting hormone melatonin and delay circadian timing, resulting in increased alertness and delayed ability to sleep. This K01 research project will examine the feasibility and preliminary efficacy of two evening light mitigation strategies to advance the timing of sleep and the circadian clock in children. Central to this research is accumulating evidence indicating high sensitivity of the early circadian system to light exposure in the hour before bedtime, even at low intensities. To date, however, research is lacking on light-based circadian health interventions in early childhood to improve sleep timing and behaviors. Children aged 5.0-6.9 years with parent-reported sleep onset difficulties will complete a single five-week protocol. After baseline assessments of circadian timing (dim-light melatonin onset), sleep timing, duration, and quality (actigraphy), and parent-reported sleep behaviors, children will be randomly assigned to one of three two-week intervention strategies: (1) adjustment to home lighting environment (implementation of smart lightbulbs to reduce short-wavelength light and light intensity 1 h before bedtime); (2) reduction in evening light exposure (amber-tinted glasses 1 h before bedtime); or (3) a sham intervention (clear glasses 1 h before bedtime). Post- intervention, a secondary assessment of all outcomes will be performed, as well as qualitative interviews with parents. These data will be used to examine the feasibility and acceptability of the intervention components (Aim 1), their preliminary efficacy in advancing children’s sleep and circadian timing (Aim 2), and whether individual differences in photosensitivity (assessed via pupillometry) moderate the response to the intervention strategies (Exploratory Aim 3). In addition to these research aims, this K01 award will incorporate training in four interdisciplinary areas: clinical and translational science, designing and implementing interventions with young children, advanced methods in photometry and photosensitivity, and biostatistics and professional development. The research and training proposed will provide preliminary data for a competitive R01 application and be an important step in facilitating Dr. Hartstein’s transition into an independent scientist with a research program committed to examining modifiable environmental and behavioral factors affecting children’s sleep and circadian health.
