Mechanisms Mediating Summer Heat Effects on Mental Health: Examining Sleep, Physical Activity, and Cognitive Pathways in Young Adults with Affective Disorders

As climate change drives rising temperatures, research shows heat affects mood, particularly in young adults. Sleep-wake disturbance, cognition, and physical activity may mediate this relationship and offer ideal targets for interventions given they are measurable and modifiable. We propose to study the relationship of temperature, sleep, cognition, and physical activity on mood using a two-pronged approach combining nationwide monitoring and controlled laboratory studies in US young adults with depression and/or anxiety. We plan to measure 1) the direct relationship between ambient temperature and mood, 2) test sleep-wake disturbance, cognitive performance, and physical activity as mediators of this relationship, 3) measure differential effects of daytime and nighttime heat on mood, and 4) assess how heat affects mood and cognition during nocturnal wakefulness. Our interdisciplinary team combines expertise in young adult mood disorders, atmospheric science, sleep research, biostatistics, ecological momentary assessment, heat physiology, cognition, and monitoring through wearable devices. Young adult lived experience experts have helped develop this project and will help conduct the research and create multimedia resources to educate their peers about our findings. This project aligns with this call for proposals to study mechanisms by which heat affects mood disorders in vulnerable populations, with potential for developing targeted interventions.