Authors: Carson Metzler, Aaron Flores, Jennifer Vanos, Gisel Guzman-Echavarria, Kendra Rentz
Session: The role of housing and the home environment on health impacts from extreme weather events: evidence, data gaps, and policy solutions
Extreme heat is being experienced by more people across the world than ever before due to increased urbanization and climate change. Closely tied to physical and mental wellbeing, sleep quality is an under-researched health determinant at the intersection of heat and health. Recent research shows that high nighttime temperatures are linked to reduced sleep quality, delayed onset of sleep, and advanced sleep offset in high nightly temperatures especially in older adults, females, and lower-income populations. In Phoenix, AZ the local airport Sky Harbor reports an average nighty low of 27°C, with temperatures increasing each summer. Paving the way to analyze how nighttime temperatures affect sleep length and quality, data from individuals living in single-unit, multi-unit, and manufactured homes gathered as part of the HeatSuite Phoenix Pilot study was used. In this study 43 individuals (>45 years) from diverse socio-economic backgrounds had their bedroom temperatures measured, self-reported their sleep quality, and slept with a smartwatch that gathered accelerometer and heart rate data.
In the summer of 2024 in Phoenix, AZ we collected environmental data on indoor/outdoor heat exposures alongside health impacts and heat perception. We used the HeatSuite™ system, which measures radiant temperature and humidity, to quantify heat exposure within the households of participants. The HeatSuite™ system is paired with a smartwatch that measures heart rate, location, skin temperature, self-reported thermal comfort, sleep quality, urination, thirst, and heat-related symptoms (fatigue, headache, concentration problems, dizziness, stress). Blood pressure cuffs and core temperature via an oral thermometer were utilized alongside the smartwatch to better understand the health status of individuals involved in the study. This data, combined with pre- and post-surveys that describe participants’ backgrounds, socioeconomic and demographic characteristics, types of housing and building specifications, and methods of adapting to heat all aid in better understanding the participants behaviors and health outcomes. The study took place between May-October in 5 waves split into 21 day periods.
Preliminary results indicate that indoor nighttime temperature is determined predominantly by cooling methods used in homes, thermal preferences, and the ability to pay for cooling, while housing type had a reduced impact. Perceived high sleep quality, movements, heart rate while sleeping, and bedroom temperature were observed to find the ideal nightly temperature range for maximum quality sleep of our participants, which came out to 17-22°C. Participants who were considered more ‘at-risk’ for reduced sleep quality and length reported lower sleep quality more frequently, as well as higher measured indoor temperatures. Participants that reported not having consistent access or a lack of air conditioning all fit within the aforementioned at-risk demographic as well.
These findings demonstrate important implications for the less-researched aspects of climate change and heat with respect to health, specifically nighttime heat exposure on sleep. Access to temperature data inside individuals’ bedrooms provided an opportunity to address a gap in the literature, which commonly utilizes nearby weather station data. Gathering information about individuals’ behaviors and adaptations taken to deal with extreme heat, throughout both day and night highlights the need for improved access to quality cooling systems. Strategies to mitigate urban heat, such as increased shade, should be increasingly prioritized to help reduce nighttime temperatures in an increasingly hot world.
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