Good news for hot sleepers: Banishing sweaty nights isn’t the only reason to keep your bedroom temperature crisp. According to new research, the temperature you set your thermostat to at night may have some real consequences for your health, especially as we age. Scientists found that sleeping in cooler temperatures may boost heart health.
Meet the experts: Lily Dastmalchi, D.O., M.A., board-certified cardiologist; Cheng-Han Chen, M.D., board-certified interventional cardiologist and medical director of the Structural Heart Program at MemorialCare Saddleback Medical Center in Laguna Hills, CA.
The takeaway comes from a recent study published in BMC Medicine, which sought to identify the best temperature for sleep in light of increasingly hot nights due to climate change. The researchers examined 47 participants in Queensland, Australia, who were all 65 or older. The participants wore fitness trackers while they slept over the course of one summer, which the researchers used to gather data on their heart rate and heart rate variability (HRV), or the amount of time between consecutive heartbeats. Sensors installed in the participants’ bedrooms continuously monitored the temperature of the room, which ranged from less than 79°F to a toasty 90°F.
By the end of the study, the researchers observed that participants who slept at higher temperatures showed increased heart rate, autonomic nervous system disruption (or essentially, stress, measured by reduced HRV), and greater physiological stress, with the effects increasing as temperature rose. So, is it time to rethink your thermostat settings? Cardiologists break down the findings below.
Why are the findings significant?
Disruptions to our sleep don’t just affect how well-rested we feel; they also have a ripple effect that makes its way into other aspects of our overall health. “Improved sleep quality is important for metabolic health, mental health, and ultimately cardiovascular health,” explains Lily Dastmalchi, D.O., M.A., a board-certified cardiologist. “Poor sleep quality can increase the risk of heart disease as it is one of the risk factors noted by Life’s Essential 8,” a list of key measures for improving cardiovascular health provided by the American Heart Association (AHA).
The association between higher bedroom temperatures and autonomic disruption is particularly revealing. “The autonomic nervous system plays an important role in cardiovascular health by regulating vital systems, including heart rate, blood pressure, and heart muscle contraction strength,” says Cheng-Han Chen, M.D., a board-certified interventional cardiologist and medical director of the Structural Heart Program at MemorialCare Saddleback Medical Center in Laguna Hills, CA. “Disruptions in this system can lead to serious heart conditions such as arrhythmia, heart failure, and even sudden death.”
What does this mean for you?
The main takeaway is that lowering the thermostat a couple of degrees could make a big difference. “It is important to maintain a comfortable sleeping environment (in the 60s Fahrenheit) to optimize heart health,” Dr. Chen stresses. “Stress during sleeping, including that from high temperatures, can adversely affect sleep quality.”
That said, Dr. Dastmalchi cautions that there is a flip side to this, and it is possible for sleeping temperatures to be too cold for some people. “The association with sleep quality and temperature varies, where both too cold temperatures and too warm temperatures can decrease sleep quality,” she explains. “There are some adult populations that benefit from warmer temperatures, like people with poor circulation or conditions such as Raynaud’s.”
What’s more, while this study emphasizes the role of temperature in causing stress during sleep, it’s not the only factor to consider. Avoiding other common habits that hurt sleep quality, like leaving screens on throughout the night, consuming caffeine or alcohol too late in the day, or doing intense evening workouts, can all contribute to a better night’s sleep.
The bottom line
This study “is an important starting point for future research into how sleep temperatures can affect heart health,” according to Dr. Chen, but there’s still more to consider, including the study’s very specific population in terms of age and location. “This was a small study involving 47 individuals; the results will need to be validated in a larger and more diverse population,” he explains.
Dr. Dastmalchi also notes that the research was observational, which means it can’t establish a true cause-and-effect relationship between sleeping temperature and heart health. Since the participants slept in their own homes during the course of the study, and not experimental environments under the complete control of the researchers, there may have been other factors at play. Still, something as simple as lowering your thermostat could be an effective way to boost your heart health in your sleep.
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