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.”
If you look back on the last century of scientific achievements, you might notice that most of the scientists we celebrate are overwhelmingly white, while scientists of color take a backseat. Since the Nobel Prize was introduced in 1901, for example, no black scientists have landed this prestigious award.
The work of black women scientists has gone unrecognized in particular. Their work uncredited and often stolen, black women have nevertheless contributed to some of the most important advancements of the last 100 years, from the polio vaccine to GPS.
Here are five black women who have changed science forever.
Dr. May Edward Chinn
Dr. May Edward Chinn practicing medicine in Harlem
George B. Davis, PhD.
Chinn was born to poor parents in New York City just before the start of the 20th century. Although she showed great promise as a pianist, playing with the legendary musician Paul Robeson throughout the 1920s, she decided to study medicine instead. Chinn, like other black doctors of the time, were barred from studying or practicing in New York hospitals. So Chinn formed a private practice and made house calls, sometimes operating in patients’ living rooms, using an ironing board as a makeshift operating table.
Chinn worked among the city’s poor, and in doing this, started to notice her patients had late-stage cancers that often had gone undetected or untreated for years. To learn more about cancer and its prevention, Chinn begged information off white doctors who were willing to share with her, and even accompanied her patients to other clinic appointments in the city, claiming to be the family physician. Chinn took this information and integrated it into her own practice, creating guidelines for early cancer detection that were revolutionary at the time—for instance, checking patient health histories, checking family histories, performing routine pap smears, and screening patients for cancer even before they showed symptoms. For years, Chinn was the only black female doctor working in Harlem, and she continued to work closely with the poor and advocate for early cancer screenings until she retired at age 81.
Alice Ball
Pictorial Press Ltd/Alamy
Alice Ball was a chemist best known for her groundbreaking work on the development of the “Ball Method,” the first successful treatment for those suffering from leprosy during the early 20th century.
In 1916, while she was an undergraduate student at the University of Hawaii, Ball studied the effects of Chaulmoogra oil in treating leprosy. This oil was a well-established therapy in Asian countries, but it had such a foul taste and led to such unpleasant side effects that many patients refused to take it.
So Ball developed a method to isolate and extract the active compounds from Chaulmoogra oil to create an injectable medicine. This marked a significant breakthrough in leprosy treatment and became the standard of care for several decades afterward.
Unfortunately, Ball died before she could publish her results, and credit for this discovery was given to another scientist. One of her colleagues, however, was able to properly credit her in a publication in 1922.
Henrietta Lacks
onathan Newton/The Washington Post/Getty
The person who arguably contributed the most to scientific research in the last century, surprisingly, wasn’t even a scientist. Henrietta Lacks was a tobacco farmer and mother of five children who lived in Maryland during the 1940s. In 1951, Lacks visited Johns Hopkins Hospital where doctors found a cancerous tumor on her cervix. Before treating the tumor, the doctor who examined Lacks clipped two small samples of tissue from Lacks’ cervix without her knowledge or consent—something unthinkable today thanks to informed consent practices, but commonplace back then.
As Lacks underwent treatment for her cancer, her tissue samples made their way to the desk of George Otto Gey, a cancer researcher at Johns Hopkins. He noticed that unlike the other cell cultures that came into his lab, Lacks’ cells grew and multiplied instead of dying out. Lacks’ cells were “immortal,” meaning that because of a genetic defect, they were able to reproduce indefinitely as long as certain conditions were kept stable inside the lab.
Gey started shipping Lacks’ cells to other researchers across the globe, and scientists were thrilled to have an unlimited amount of sturdy human cells with which to experiment. Long after Lacks died of cervical cancer in 1951, her cells continued to multiply and scientists continued to use them to develop cancer treatments, to learn more about HIV/AIDS, to pioneer fertility treatments like in vitro fertilization, and to develop the polio vaccine. To this day, Lacks’ cells have saved an estimated 10 million lives, and her family is beginning to get the compensation and recognition that Henrietta deserved.
Dr. Gladys West
Andre West
Gladys West was a mathematician who helped invent something nearly everyone uses today. West started her career in the 1950s at the Naval Surface Warfare Center Dahlgren Division in Virginia, and took data from satellites to create a mathematical model of the Earth’s shape and gravitational field. This important work would lay the groundwork for the technology that would later become the Global Positioning System, or GPS. West’s work was not widely recognized until she was honored by the US Air Force in 2018.
Dr. Kizzmekia "Kizzy" Corbett
TIME Magazine
At just 35 years old, immunologist Kizzmekia “Kizzy” Corbett has already made history. A viral immunologist by training, Corbett studied coronaviruses at the National Institutes of Health (NIH) and researched possible vaccines for coronaviruses such as SARS (Severe Acute Respiratory Syndrome) and MERS (Middle East Respiratory Syndrome).
At the start of the COVID pandemic, Corbett and her team at the NIH partnered with pharmaceutical giant Moderna to develop an mRNA-based vaccine against the virus. Corbett’s previous work with mRNA and coronaviruses was vital in developing the vaccine, which became one of the first to be authorized for emergency use in the United States. The vaccine, along with others, is responsible for saving an estimated 14 million lives.On today’s episode of Making Sense of Science, I’m honored to be joined by Dr. Paul Song, a physician, oncologist, progressive activist and biotech chief medical officer. Through his company, NKGen Biotech, Dr. Song is leveraging the power of patients’ own immune systems by supercharging the body’s natural killer cells to make new treatments for Alzheimer’s and cancer.
Whereas other treatments for Alzheimer’s focus directly on reducing the build-up of proteins in the brain such as amyloid and tau in patients will mild cognitive impairment, NKGen is seeking to help patients that much of the rest of the medical community has written off as hopeless cases, those with late stage Alzheimer’s. And in small studies, NKGen has shown remarkable results, even improvement in the symptoms of people with these very progressed forms of Alzheimer’s, above and beyond slowing down the disease.
In the realm of cancer, Dr. Song is similarly setting his sights on another group of patients for whom treatment options are few and far between: people with solid tumors. Whereas some gradual progress has been made in treating blood cancers such as certain leukemias in past few decades, solid tumors have been even more of a challenge. But Dr. Song’s approach of using natural killer cells to treat solid tumors is promising. You may have heard of CAR-T, which uses genetic engineering to introduce cells into the body that have a particular function to help treat a disease. NKGen focuses on other means to enhance the 40 plus receptors of natural killer cells, making them more receptive and sensitive to picking out cancer cells.
Paul Y. Song, MD is currently CEO and Vice Chairman of NKGen Biotech. Dr. Song’s last clinical role was Asst. Professor at the Samuel Oschin Cancer Center at Cedars Sinai Medical Center.
Dr. Song served as the very first visiting fellow on healthcare policy in the California Department of Insurance in 2013. He is currently on the advisory board of the Pritzker School of Molecular Engineering at the University of Chicago and a board member of Mercy Corps, The Center for Health and Democracy, and Gideon’s Promise.
Dr. Song graduated with honors from the University of Chicago and received his MD from George Washington University. He completed his residency in radiation oncology at the University of Chicago where he served as Chief Resident and did a brachytherapy fellowship at the Institute Gustave Roussy in Villejuif, France. He was also awarded an ASTRO research fellowship in 1995 for his research in radiation inducible gene therapy.
With Dr. Song’s leadership, NKGen Biotech’s work on natural killer cells represents cutting-edge science leading to key findings and important pieces of the puzzle for treating two of humanity’s most intractable diseases.
Show links
- Paul Song LinkedIn
- NKGen Biotech on Twitter - @NKGenBiotech
- NKGen Website: https://nkgenbiotech.com/
- NKGen appoints Paul Song
- Patient Story: https://pix11.com/news/local-news/long-island/promising-new-treatment-for-advanced-alzheimers-patients/
- FDA Clearance: https://nkgenbiotech.com/nkgen-biotech-receives-ind-clearance-from-fda-for-snk02-allogeneic-natural-killer-cell-therapy-for-solid-tumors/Q3 earnings data: https://www.nasdaq.com/press-release/nkgen-biotech-inc.-reports-third-quarter-2023-financial-results-and-business