Wear sunscreen, avoid tobacco, and eat a balanced diet are all common pieces of advice to reduce the risk of developing cancer, but the role of sleep is rarely discussed.
In this feature for National Cancer Prevention Month, readers can learn about some of the ways Washington State University Elson S. Floyd College of Medicine researchers are investigating the link between peoples’ sleep and their risk of developing the often-fatal disease.
At the Sleep and Performance Research Center, for example, researchers aim to better understand the role of sleep deprivation and circadian rhythm disruption in cancer. Below are several projects currently being conducted at the center that are part of a growing body of research showing that different aspects of sleep, including timing and quality, can affect cancer risk as well as response to treatment.
Chronotherapy and the damaging effect of sleep deprivation on cancer risk
Supported by the Henning Cancer gift to the College of Medicine, WSU circadian biologist Yool Lee, PhD, and his team study the role of circadian rhythms in cancer treatment and progression in osteosarcoma and glioblastoma, or bone and brain cancer.
A circadian rhythm is the body’s natural cycle of sleeping, waking, and eating, cued by environmental factors such as light and dark. Almost all cells in the body have their own circadian clocks.
Most cancer treatments are given without consideration to the time of day. However, Lee said that’s a mistake.
His lab recently tested how effective different anti-cancer drugs were at shrinking osteosarcoma tumors in the lab based on the time of day they were administered and found that timing matters.
“Osteosarcoma cells show different responses to treatment depending on what time they’re treated,” Lee said. “The best time of day depends on the drug.”
Another focus of Lee’s research is investigating how sleep deprivation and disruption to circadian rhythms affect tumor development. Past research has shown that circadian rhythm disruption, like chronic jet lag, can have profoundly negative consequences for people’s health. Building on this, Lee’s prior research uncovered how chronic circadian disturbances speed up cancer growth at the molecular and cellular levels.
Now, Lee is exploring whether circadian disruption also increases people’s risk of cancer by affecting the body’s immune system. His work shows that even a single night of sleep deprivation can potentially suppress immune cells and interfere with their cancer-killing capabilities.
Understanding and addressing increased cancer risk from shift work
Neuroscientist and sleep researcher Brieann Satterfield, PhD, is looking at the effects of sleep deprivation and circadian rhythm disruption on cancer in one underserved population in particular: shift workers.
Approximately 15% of the U.S. population does shift work, or work done outside of a typical 9 a.m. to 5 p.m. schedule. Shift work is associated with a range of poor health outcomes, including a greater risk of heart disease, obesity, diabetes, and depression.
Like Lee, Satterfield and colleagues at the Sleep and Performance Research Center have found that even a few nights of sleep displacement can have striking and negative consequences for cancer risk.
“This population is substantially underserved with regard to health research and clinical practices,” Satterfield said. “They’re kind of ignored. They’re just this workforce that does everything in the background that most of us don’t even interact with, but they suffer a much higher health burden than the rest of us.”
One experiment at the center’s Human Sleep and Cognition Lab explored the effects of circadian rhythm disruption at the cellular level. Volunteers who had never worked night shifts were brought to the lab for three days and assigned to either work during the day as usual or to work during the night, disrupting their circadian rhythms. The researchers then collected blood samples to analyze the differences between the two groups.
“We found increased DNA damage in individuals that were on the night shift schedule,” Satterfield said. This also included a change in circadian rhythms of DNA repair genes, which help fix everyday damage to DNA that can cause cancer. “It’s pretty amazing to me that we had such profound effects after three days.”
While study volunteers returned to their normal schedules and their bodies repaired the damage, these findings are especially concerning for people who have done shift work for years and accumulate damage over time, Satterfield said.
One of her current projects, funded by the state’s Andy Hill Cancer Research Endowment Fund and the Health Sciences and Services Authority of Spokane County, is studying this damage in people who have worked night shifts in “the real world” outside of the lab for at least five years.
The ultimate goal of the research will be to identify preventative measures or therapies that reduce shift work health risks, Satterfield said.
