Think again: Fatigue and survivors

St. Jude scientists discover that childhood cancer survivors are particularly vulnerable to the effects of fatigue and sleep deprivation.

by Elizabeth Jane Walker

Kevin R. Krull, PhD

Just before you drift off to sleep tonight, think about Quay West. Odds are, she’s wide awake.

Quay, a survivor of Hodgkin lymphoma, suffers from insomnia. Ironically, her inability to sleep has nothing to do with the fact that she manages a college residence hall, where students come and go at all hours of the night.

“My sleep and fatigue problems began 25 years ago,” says Quay, who underwent treatment for her cancer at St. Jude Children’s Research Hospital. “They started even before I went through chemotherapy, but they’ve gotten progressively worse. There have been weeks that I’ve gone three or four days with just an hour or two of sleep. The worst was five days with maybe an hour of sleep.”

Scientists have long acknowledged that many childhood cancer survivors experience marked fatigue and poor sleep quality. When compared with healthy members of the population, cancer survivors also experience more trouble with mental processing speed, attention, reasoning and memory.

Until recently, scientists did not know that survivors were particularly vulnerable to the impact of fatigue and sleep quality on memory, organizational skills, emotional control and task efficiency. Kevin Krull, PhD, of St. Jude Epidemiology and Cancer Control, and his colleagues led a study revealing that connection. Results of their research recently appeared in the journal Cancer.


The study involved 1,426 childhood cancer survivors and 384 healthy siblings enrolled in the Childhood Cancer Survivor Study  (CCSS). Headquartered at St. Jude and funded by the National Cancer Institute, the CCSS now encompasses 30 collaborating institutions located throughout the United States and Canada.

Cancer survivors who have undergone radiation therapy to the brain or who have received chemotherapy that affects the brain have an increased risk of cognitive problems. Krull and his team discovered that fatigue and sleep impairment exacerbates those issues for all survivors, regardless of the type of cancer therapy they received.

“If you or I miss some sleep for a while, we may be able to deal with it, compensate and muster the resources to function adequately,” Krull says. “Cancer survivors have much more difficulty with that.”

Krull and his colleagues discovered that survivors with sleep problems had a three- to four-fold higher risk of attention and memory impairments than their siblings did. The childhood cancer survivors also indicated slower cognitive processing speed and more difficulty regulating their emotions.

Like an irritating bee that buzzes just outside of her reach, the most basic words often elude Quay.

“One day, I couldn’t think of the word ‘truck,’” she says. “I was sitting there with the mental image of the vehicle, but I couldn’t get the word ‘truck’ out. I attributed it to my fatigue.”

Re-collecting recollections

Scientists have begun to design new therapies and interventions to help individuals like Quay. Krull says survivors may benefit from periodic screenings of their sleep habits and fatigue levels. Survivors may also benefit from memory training, a skill-based approach that allows them to repeatedly practice getting details into their memory and then retrieving that information.

The hospital has an ongoing study to determine whether Web-based skill training may help survivors improve memory and attention functions. Participants are also provided instruction on strategy techniques that include using memory notebooks; employing simple organizational strategies such as putting keys in the same place every day; and repeating facts until they are lodged in memory and can be retrieved.

Krull also points out that some survivors may benefit from intensive aerobic exercise. St. Jude is designing an exercise intervention to determine whether exercise may help to improve memory function in cancer survivors who are at risk for those difficulties. Researchers are also looking at biomarkers in fatigued survivors to see if they exhibit signs of inflammation.

A couple of years ago, Quay returned to the hospital to participate in the St. Jude LIFE  study, which studies the long-term effects of cancer and its treatment. Physicians talked with her about the importance of exercise, especially for those who suffer from insomnia.

“Exercise does seem to make me feel and think better,” Quay observes. “My cancer treatment affected my heart, so I can’t do anything super-strenuous. I do weight training, and I walk and work out on the elliptical machine. But because of the lack of sleep, sometimes I don’t have the energy at the end of the day to exercise.”

Sweet dreams

Krull and his colleagues are also planning a new intervention that includes what he calls sleep hygiene, or activities that promote and encourage sleep. By helping patients fall asleep and improve their sleep quality, the researchers hope to improve survivors’ cognitive function as well.

Activities may be as simple as avoiding caffeine after noon, exercising before 5 p.m., ensuring proper nutrition, taking a warm bath and avoiding reading or watching TV in bed.

“We’ve already developed sleep hygiene educational materials that we put on our website and that we provide to our adult population in our St. Jude LIFE study,” Krull says. “We provide this educational component as a standard of care of those who are having cognitive problems and are reporting sleep difficulties.”

Quay hopes those kinds of interventions will help her.

“The insomnia and fatigue have most definitely affected my memory and organizational skills,” she says. “I never finished college because of that. If I could find a way to go to sleep naturally, that would be awesome. Then I could think about going back to school and finishing my degree.”

Promise magazine, Summer 2011

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