High on Health: Is Your Bedroom Too Hot for Your Heart?

Getting a full night’s restful sleep is one of the best things you can do for your health. Comfort is a big proponent of good sleep, but what happens when being comfortable might actually be bad for you? A new study showed that having the temperature too hot in the bedroom could actually be bad for your heart, especially in older people.

Bedroom Temperature and Heart Health

A study from Griffith University in Queensland, Australia, followed the bedroom temperatures of 47 adults who were 65 years and older and discovered that heat does make a difference. The hotter it is, the harder the heart has to work to cool down the body. “However, when the heart works harder and for longer, it creates stress and limits our capacity to recover from the previous day’s heat exposure,” Dr. Fergus O’Connor, lead study author, stated in a press release.

The research was conducted as a “free-living” study, which means the participants were observed during normal activities and sleep schedules. They wore fitness trackers to monitor their heart rates, and thermostats kept track of the temperature in the bedrooms. The study took place during an Australian summer, from December to March, and heart rates were monitored from 9 p.m. to 7 a.m.

"For individuals aged 65 years and over, maintaining overnight bedroom temperatures at 24 C (75.2 F) reduced the likelihood of experiencing heightened stress responses during sleep," O'Connor said.

The research paper, “Effect of nighttime bedroom temperature on heart rate variability in older adults: an observational study,” published in BMC Medicine, noted that when the bedroom temperature was more than 75 degrees, the heart began to show signs of disruption. When the heat climbed between 75 and 79 degrees Fahrenheit, the odds of a “clinically relevant” drop in heart recovery rose by 40%. A room temperature between 79 and 82 meant those odds doubled, and for those who truly love the heat, bedrooms above 82 degrees had a nearly triple risk.

This could be good news for menopausal women who might enjoy sub-zero bedroom temperatures, but not a pleasant finding for those who like to snuggle up with heavy blankets and temperatures rivaling a hot summer’s day.

As Dr. O’Connor explained: "When the human body is exposed to heat, its normal physiological response is to increase the heart rate. The heart is working harder to try and circulate blood to the skin surface for cooling.”

As ScienceDaily observed, “The results provided the first real-world evidence showing how higher bedroom temperatures directly affect heart rate and stress responses during sleep.”

The study mentioned that although there are guidelines for maximum daytime indoor temperatures according to the World Health Organization, there are no such suggestions for nighttime. During the day, the health organization suggests a maximum of 79 degrees, which, according to the study paper, could double heart health risk while sleeping.

Sudden Cardiac Death While Sleeping

The bedroom temperature isn’t the only thing that can contribute to heart health issues, of course. There are a multitude of other factors that may play a part, including disease, medications, age, and habits.

Sudden Cardiac Death (SCD) is when someone dies, usually within an hour, of the onset of cardiac symptoms. According to a paper published by the Heart Rhythm Society, 17-41% “of all SCD events occur during nighttime hours.”

The Heart Rhythm Society’s study was based on the Oregon Sudden Unexpected Death Study, in which researchers evaluated SCD cases that occurred in the community between 10 p.m. and 6 a.m. They studied the deaths of 4,126 people, of whom 66.2% were male and 33.8% were female. “Women were more likely to present with nighttime SCD than men,” the study showed.

Medications can play a role in sudden cardiac death. Heart Rhythm’s study found that women were taking more central nervous system-affecting medications than men: 73% compared to 65.7% respectively. Central nervous system agents range from acetaminophen to amphetamines and everywhere in between.

So before you crank the thermostat up and pile on three quilts like you’re camping in Antarctica or turn your bedroom into a tropical greenhouse, remember that your heart has to live there, too. A cozy room might feel like a hug, but if it’s too hot, your body spends the night doing cardio instead of resting. Good sleep should recharge you, not send your heart clocking in for overtime, because the only thing that should be racing at 2 a.m. is your imagination, not your pulse.