As atmospheric sensible and latent heat increase, the human body's ability to thermoregulate its core temperature is negatively impacted. This can be particularly dangerous to the elderly due to already altered regulatory systems and/or medical conditions that may interfere with thermoregulation. Recent research has further supported that there is an association between high temperatures and decreased sleep quality. Further, the World Health Organization has named sleep deprivation as one of several risk factors for developing heat-related illnesses. During sleep, the body conserves energy. When sleep is diminished during periods of extreme heat, more energy than normal is needed for regular function, making the body more susceptible to heat stress and other health complications.
A participatory research project has been conducted in Cambridge, Massachusetts to assess how the indoor environment impacts sleep quality, and therefore health, during periods of extreme heat in older adults. Volunteers were recruited from two buildings with different cooling systems. Study participants in building 1 (n=26) have central air conditioning in their units while participants in building 2 (n=26) rely on a combination of natural ventilation and window AC units.
Participants were monitored for one week during a period of average summer temperatures and again for one week during a period of extreme summer temperatures. During each phase of the study, participants wore a health monitoring watch that measured skin temperature, sleep patterns, perspiration, heart rate, and daily activity. An indoor environmental sensor was placed in each participant's bedroom to monitor indoor temperature, air quality, noise, and humidity. Participants also completed a baseline assessment of their living conditions, sleep quality, and self-reported health, as well as daily activity and sleep logs during each phase of the study.
The objective of this study was to understand the associations between sleep quality and health in this population, within the same participant over the time period, between participants, and between buildings. Throughout field visits though, several other discoveries were realized that are important to the future of urban building design, public health, heat exposure in vulnerable populations, and climate change adaptation.
It was originally thought that central air conditioning would be the preferred option for this population in terms of thermal comfort and reducing heat stress. However, participants were more apt to not use air conditioning during moderately high temperatures, reducing their exposure to drastic temperature variability when moving between indoor and outdoor environments during the warm season. Preliminary results pertaining to the immediate effects on the environment and public health communities and a discussion of the widespread implications for the health sensor, urban and building design, as well as energy usage communities will be discussed.