The quality of sleep is key in the consolidation of memories, muscle repair, keeping ours brain clear of waste and a score of other vital bodily functions. Thus, it is important to understand what factors can disrupt sleep, including a changing environment. A recent article in Science Advances discusses how increasing nighttime temperatures due to climate change may impact human sleep cycles.
The process of falling and staying asleep relies on several determinants, one of which is the drop of core body temperature. Anyone who has tried to fall asleep in a room without air conditioning in a city during the summer understands how a hot room can make it very difficult to get a good night’s sleep. Researchers deduced that as the global temperature steadily increases each year then the incidence of insufficient sleep would as well. This association is of supreme importance to understand as chronic insufficient sleep has been linked to pathology in inflammatory diseases, weakened immune systems, dysfunctions in metabolism and psychological health. These can ultimately lead to problems such as cardiovascular disease, diabetes, and depression.
To assess this relationship, 765,000 randomly selected U.S. residents reported on their sleep over 2002-2011 using the Centers for Disease Control and Prevention Behavioral Risk Factor Surveillance Survey (BRFSS), which has been used in several other public health studies concerning sleep. There are countless variables aside from temperature that can affect sleep and more variables still that can attenuate the nighttime temperature-sleep quality association. To avoid any bias, researchers devised several complex equations that would control for these variables such as access to air conditioning, geographical location, and time of year amongst others.
The data collected showed a strong link between abnormal nighttime temperatures and insufficient sleep that is most pronounced during the summer months. The populations most impacted were low-income individuals and the elderly with low-income elderly being the most negatively affected. These findings complement a growing literature on the subject of temperature and human health but was the first to focus on the effect of climate change. Although this study was able to collect data from hundreds of thousands of subjects it is important to understand that this data was mostly subjective, meaning it was reported by the individual and not measured or observed. It also could not take into account pre-existing conditions such as undiagnosed sleep apnea, nighttime use of technology, and other modifiers that have been shown to impact sleep.
Further research on this subject would be globally beneficial as the effect of climate change will influence all of us, especially those in developing countries where climate controlled alternatives are not always readily available.
Written By: Clifton Lewis