New study: Hotter nights, climate change, cause sleep loss with some affected more than others
Data from the National Sleep Foundation finds that the optimal bedroom temperature for sleep is around 65 degrees Fahrenheit. But we may be getting fewer hours of "good sleepin’ weather" as the climate warms, according to a recent paper from researchers at the University of Copenhagen, Denmark.
Published in One Earth, the study finds that heat related to climate change could provide a “pathway” to sleep deprivation. The authors say the effect is “substantially larger” for those in lower-income countries. Hours of sleep decline when nighttime temperature exceeds 50 degrees, and temps higher than 77 reduce the chances of sleeping for seven hours by 3.5 percent. Even small losses associated with rising temperatures contribute significantly to people not getting enough sleep.
We’re affected by high temperatures at night because body temperature becomes more sensitive to the environment when slumbering. “Mechanisms that control for thermal regulation become more disordered during sleep,” explains Clete Kushida, a neurologist, professor of psychiatry at Stanford University and sleep medicine clinician.
The study finds that women and older adults are especially vulnerable. Worldwide, the elderly lost over twice as much sleep per degree of warming compared to younger people. This phenomenon was apparent between the ages of 60 and 70, and it increased beyond age 70. “The mechanism for balancing temperatures appears to be more affected with age,” Kushida adds.
Others disproportionately affected include those who live in regions with more greenhouse gas (GHG) emissions, which accelerate climate change, and people in hotter locales will lose more sleep per degree of warming, according to the study, with suboptimal temperatures potentially eroding 50 to 58 hours of sleep per person per year. One might think that those in warmer countries can adapt to the heat, but the researchers found no evidence for such adjustments. “We actually found those living in the warmest climate regions were impacted over twice as much as those in the coldest climate regions,” says the study's lead author, Kelton Minor, a Ph.D. candidate at the University of Copenhagen’s Center for Social Data Science.
Short sleep can reduce cognitive performance and productivity, increase absenteeism from work or school, and lead to a host of other physical and psychosocial problems. These issues include a compromised immune system, hypertension, depression, anger and suicide, say the study’s authors. According to a fact sheet by the U.S. Centers for Disease Control and Prevention, a third of U.S. adults already report sleeping fewer hours than the recommended amount, even though sufficient sleep “is not a luxury—it is something people need for good health.”
Equitable policy and planning are needed to ensure equal access to cooling technologies in a warming world.
Beyond global health, a sleep-deprived world will impact the economy as the climate warms. “Less productivity at work, associated with sleep loss or deprivation, would result in more sick days on a global scale, not just in individual countries,” Kushida says.
Unlike previous research that measured sleep patterns with self-reported surveys and controlled lab experiments, the study in One Earth offers a global analysis that relies on sleep-tracking wristbands that link more than seven million sleep records of 47,628 adults across 68 countries to local and daily meteorological data, offering new insight into the environmental impact on human sleep. Controlling for individual, seasonal and time-varying confounds, researchers found the main way that higher temperatures shorten slumber is by delaying sleep onset.
Heat effects on sleep were seen in industrialized countries including those with access to air conditioning, notes the study. Air conditioning may buffer high indoor temperatures, but they also increase GHG emissions and ambient heat displacement, thereby exacerbating the unequal burdens of global and local warming. Continued urbanization is expected to contribute to these problems.
Previous sleep studies have found an inverse U-shaped response to temperature in highly controlled settings, with subjects sleeping worse when room temperatures were either too cold or too warm. However, “people appear far better at adapting to colder outside temperatures than hotter conditions,” says Minor.
Although there are ways of countering the heat effect, some populations have more access to them. “Air conditioning can help with the effect of higher temperature, but not all individuals can afford air conditioners,” says Kushida. He points out that this could drive even greater inequity between higher- and lower-income countries.
Equitable policy and planning are needed to ensure equal access to cooling technologies in a warming world. “Clean and renewable energy systems and interventions will be needed to mitigate and adapt to ongoing climate warming,” Minor says. Future research should investigate “policy, planning and design innovation,” which could reduce the impact of sweltering temperatures on a good night’s sleep for the good of individuals, society and our planet, asserts the study.
Unabated and on its current trajectory, by 2099 suboptimal temperatures could shave 50 to 58 hours of sleep per person per year, predict the study authors. “Down the road, as technology develops, there might be ways of enabling people to adapt on a large scale to these higher temperatures,” says Kushida. “Right now, it’s not there.”
This man spent over 70 years in an iron lung. What he was able to accomplish is amazing.
It’s a sight we don’t normally see these days: A man lying prone in a big, metal tube with his head sticking out of one end. But it wasn’t so long ago that this sight was unfortunately much more common.
In the first half of the 20th century, tens of thousands of people each year were infected by polio—a highly contagious virus that attacks nerves in the spinal cord and brainstem. Many people survived polio, but a small percentage of people who did were left permanently paralyzed from the virus, requiring support to help them breathe. This support, known as an “iron lung,” manually pulled oxygen in and out of a person’s lungs by changing the pressure inside the machine.
Paul Alexander was one of several thousand who were infected and paralyzed by polio in 1952. That year, a polio epidemic swept the United States, forcing businesses to close and polio wards in hospitals all over the country to fill up with sick children. When Paul caught polio in the summer of 1952, doctors urged his parents to let him rest and recover at home, since the hospital in his home suburb of Dallas, Texas was already overrun with polio patients.
Paul rested in bed for a few days with aching limbs and a fever. But his condition quickly got worse. Within a week, Paul could no longer speak or swallow, and his parents rushed him to the local hospital where the doctors performed an emergency procedure to help him breathe. Paul woke from the surgery three days later, and found himself unable to move and lying inside an iron lung in the polio ward, surrounded by rows of other paralyzed children.
Hospitals were commonly filled with polio patients who had been paralyzed by the virus before a vaccine became widely available in 1955. Associated Press
Paul struggled inside the polio ward for the next 18 months, bored and restless and needing to hold his breath when the nurses opened the iron lung to help him bathe. The doctors on the ward frequently told his parents that Paul was going to die.But against all odds, Paul lived. And with help from a physical therapist, Paul was able to thrive—sometimes for small periods outside the iron lung.
The way Paul did this was to practice glossopharyngeal breathing (or as Paul called it, “frog breathing”), where he would trap air in his mouth and force it down his throat and into his lungs by flattening his tongue. This breathing technique, taught to him by his physical therapist, would allow Paul to leave the iron lung for increasing periods of time.
With help from his iron lung (and for small periods of time without it), Paul managed to live a full, happy, and sometimes record-breaking life. At 21, Paul became the first person in Dallas, Texas to graduate high school without attending class in person, owing his success to memorization rather than taking notes. After high school, Paul received a scholarship to Southern Methodist University and pursued his dream of becoming a trial lawyer and successfully represented clients in court.
Paul Alexander, pictured here in his early 20s, mastered a type of breathing technique that allowed him to spend short amounts of time outside his iron lung. Paul Alexander
Paul practiced law in North Texas for more than 30 years, using a modified wheelchair that held his body upright. During his career, Paul even represented members of the biker gang Hells Angels—and became so close with them he was named an honorary member.Throughout his long life, Paul was also able to fly on a plane, visit the beach, adopt a dog, fall in love, and write a memoir using a plastic stick to tap out a draft on a keyboard. In recent years, Paul joined TikTok and became a viral sensation with more than 330,000 followers. In one of his first videos, Paul advocated for vaccination and warned against another polio epidemic.
Paul was reportedly hospitalized with COVID-19 at the end of February and died on March 11th, 2024. He currently holds the Guiness World Record for longest survival inside an iron lung—71 years.
Polio thankfully no longer circulates in the United States, or in most of the world, thanks to vaccines. But Paul continues to serve as a reminder of the importance of vaccination—and the power of the human spirit.
““I’ve got some big dreams. I’m not going to accept from anybody their limitations,” he said in a 2022 interview with CNN. “My life is incredible.”
When doctors couldn’t stop her daughter’s seizures, this mom earned a PhD and found a treatment herself.
Twenty-eight years ago, Tracy Dixon-Salazaar woke to the sound of her daughter, two-year-old Savannah, in the midst of a medical emergency.
“I entered [Savannah’s room] to see her tiny little body jerking about violently in her bed,” Tracy said in an interview. “I thought she was choking.” When she and her husband frantically called 911, the paramedic told them it was likely that Savannah had had a seizure—a term neither Tracy nor her husband had ever heard before.
Over the next several years, Savannah’s seizures continued and worsened. By age five Savannah was having seizures dozens of times each day, and her parents noticed significant developmental delays. Savannah was unable to use the restroom and functioned more like a toddler than a five-year-old.
Doctors were mystified: Tracy and her husband had no family history of seizures, and there was no event—such as an injury or infection—that could have caused them. Doctors were also confused as to why Savannah’s seizures were happening so frequently despite trying different seizure medications.
Doctors eventually diagnosed Savannah with Lennox-Gaustaut Syndrome, or LGS, an epilepsy disorder with no cure and a poor prognosis. People with LGS are often resistant to several kinds of anti-seizure medications, and often suffer from developmental delays and behavioral problems. People with LGS also have a higher chance of injury as well as a higher chance of sudden unexpected death (SUDEP) due to the frequent seizures. In about 70 percent of cases, LGS has an identifiable cause such as a brain injury or genetic syndrome. In about 30 percent of cases, however, the cause is unknown.
Watching her daughter struggle through repeated seizures was devastating to Tracy and the rest of the family.
“This disease, it comes into your life. It’s uninvited. It’s unannounced and it takes over every aspect of your daily life,” said Tracy in an interview with Today.com. “Plus it’s attacking the thing that is most precious to you—your kid.”
Desperate to find some answers, Tracy began combing the medical literature for information about epilepsy and LGS. She enrolled in college courses to better understand the papers she was reading.
“Ironically, I thought I needed to go to college to take English classes to understand these papers—but soon learned it wasn’t English classes I needed, It was science,” Tracy said. When she took her first college science course, Tracy says, she “fell in love with the subject.”
Tracy was now a caregiver to Savannah, who continued to have hundreds of seizures a month, as well as a full-time student, studying late into the night and while her kids were at school, using classwork as “an outlet for the pain.”
“I couldn’t help my daughter,” Tracy said. “Studying was something I could do.”
Twelve years later, Tracy had earned a PhD in neurobiology.
After her post-doctoral training, Tracy started working at a lab that explored the genetics of epilepsy. Savannah’s doctors hadn’t found a genetic cause for her seizures, so Tracy decided to sequence her genome again to check for other abnormalities—and what she found was life-changing.
Tracy discovered that Savannah had a calcium channel mutation, meaning that too much calcium was passing through Savannah’s neural pathways, leading to seizures. The information made sense to Tracy: Anti-seizure medications often leech calcium from a person’s bones. When doctors had prescribed Savannah calcium supplements in the past to counteract these effects, her seizures had gotten worse every time she took the medication. Tracy took her discovery to Savannah’s doctor, who agreed to prescribe her a calcium blocker.
The change in Savannah was almost immediate.
Within two weeks, Savannah’s seizures had decreased by 95 percent. Once on a daily seven-drug regimen, she was soon weaned to just four, and then three. Amazingly, Tracy started to notice changes in Savannah’s personality and development, too.
“She just exploded in her personality and her talking and her walking and her potty training and oh my gosh she is just so sassy,” Tracy said in an interview.
Since starting the calcium blocker eleven years ago, Savannah has continued to make enormous strides. Though still unable to read or write, Savannah enjoys puzzles and social media. She’s “obsessed” with boys, says Tracy. And while Tracy suspects she’ll never be able to live independently, she and her daughter can now share more “normal” moments—something she never anticipated at the start of Savannah’s journey with LGS. While preparing for an event, Savannah helped Tracy get ready.
“We picked out a dress and it was the first time in our lives that we did something normal as a mother and a daughter,” she said. “It was pretty cool.”