The effect of circadian-disrupting environments on sleep and binge-like eating behavior

Oakwood University, Inc. received a $385,033 Project Grant from the National Heart, Lung, and Blood Institute (NHLBI) under the Cardiovascular Diseases Research program (CFDA 93.837) awarded on September 20, 2025, with completion targeted for August 31, 2028. The grant funds basic research investigating the effects of circadian-disrupting light-dark environments on sleep and binge-like eating behavior in animal models. Specifically, the research employs a Fragmented Day-Night (FDN) model that manipulates light exposure patterns (4 hours light + 2 hours dark cycles repeated four times per 24-hour period) to examine how the timing and manner of introduction of disrupted light-dark cycles affect neurobiological and behavioral outcomes compared to standard consolidated light-dark conditions.

The research deliverables include quantitative characterization of sleep timing disruptions and alterations in eating behavior timing when subjects are exposed to binge-eating paradigms under both sudden and gradual FDN environmental presentations. Additionally, the project will generate data on neuronal activation patterns and gene expression changes in key brain regions associated with circadian regulation, sleep, and feeding behaviors. These findings will advance understanding of how industrial light environments disrupting natural circadian rhythms influence fundamental homeostatic behaviors, with implications for cardiovascular and metabolic health research supported by NHLBI's mission to prevent and treat heart, lung, and blood diseases.

Abstract

The brain both encodes information to drive normative functions and decodes abnormal information to navigate sustenance and homeostasis in suboptimal conditions. This regulatory role is strongly influenced by the body's circadian rhythms that link the light-dark cycle of our planet with internal physiology. We do not yet understand how the brain translates disruptions to the light-dark cycle (e.g., from our industrial environments that can have light during the biological night) to regulate two fundamental behaviors required for life: sleep timing and eating, both of which are circadian-regulated. One recent approach to this problem (from the richardson lab) is the fragmented day-night (FDN) model, in which within each 24-hour cycle, there are four cycles of 4 HR light + 2 HR dark (4:2 LD) (total 16:8 LD in 24 HRS). The mode of introduction of this light-dark protocol (suddenly: FDN-s or gradually: FDN-g) determined dramatically different phenotypes of locomotion in mice, even though the resulting light-dark environments are identical. This suggests that the brain modifies behavior to the same environment based on how the environment is presented. We hypothesize that the FDN-s and FDN-g environments will also differentially (i) negatively impact sleep and eating behavior timing and (II) change neuronal activation and gene expression in key brain regions. To address these hypotheses, we ask the following questions: compared to consolidated 16 hours of light and consolidated 8 hours of darkness (i.e., control), 1) how is sleep timing, a major restorative circadian-driven behavior, affected by the FDN-s VS FDN-g environments? 2) how is eating behavior timing, which is circadian-regulated, be impacted during FDN-s and FDN-g environments when mice are challenged with a binge-eating paradigm? 3) is there a difference in neuronal activation and gene expression levels in FDN-s VS FDN-g in brain regions involved in sleep and eating behavior timing? We will accomplish our goals using (i) the piezosleep mouse behavioral tracking system to record sleep, (i) the binge-eating test to study eating behavior, (III) c-FOS immunohistochemistry to study neuronal activation, and (IV) dpcr for gene expression using wildtype (WT- C57BL/6NCRL) adult male and female mice. The brain areas of focus associated with sleep and circadian-regulated eating behavior will be the suprachiasmatic nucleus (circadian light-response), ventrolateral preoptic nucleus (sleep initiation), lateral habenula (stress- related induction of sleep), paraventricular nucleus (stress/eating behavior) and arcuate nucleus (eating behavior). This study is innovative because IT uses the same amount of light and dark exposure within 24 hours to yield three activity patterns. This work is crucial for understanding how the brain responds to the same stimulus (e.g., light) depending on how the stimulus is presented (specific LD cycles). Together with the 3-year development plan, the proposed study will serve as a unique research experience for the talented undergraduate students at oakwood university on topics integral to their daily lives: light, sleep, and eating.