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 For the month-long study, researchers had 44 cancer survivors sit
very close to a light box early every morning for 30 minutes. The
patients were randomly assigned to therapy with either bright white
light or dim red light.
More than half of the participants suffered from what’s known as
poor sleep efficiency, a measure of how much time in bed people
spend asleep. After a month of treatment, however, 86 percent of the
people exposed to bright white light had normal sleep efficiency,
while 79 percent of the people exposed to dim bright light still had
poor sleep efficiency.
It’s possible that the bright white light helps cancer survivors
reset their internal clocks, or circadian rhythms, so that their
body can more easily rest at night and wake during the day, said
study leader Lisa Wu of the Northwestern University Feinberg School
of Medicine in Chicago and the Icahn School of Medicine at Mount
Sinai in New York City.
“Cancer survivors and even other individuals who spend most of their
days indoors may not receive enough bright light to keep their
biological rhythms synchronized,” Wu said by email. “Given that
light exposure from being outside is generally much brighter than
light received indoors, the addition of artificial bright light each
morning helps cancer survivors reduce fatigue and improve their
sleep quality by strengthening their circadian rhythms.”
Beyond just improving sleep efficiency, bright white light was also
associated with medium to large improvements in sleep quality, total
sleep time and wake time, researchers report in the Journal of
Clinical Sleep Medicine.
When researchers checked back with participants three weeks after
they stopped light therapy, improvements in sleep quality associated
with bright white light had disappeared, and this group no longer
fared better than people who had been exposed to dim red light.
This suggests that ongoing therapy may be needed for cancer
survivors to experience a sustained improvement in sleep.
Beyond its small size, another limitation of the study is that the
cancer survivors were screened only for cancer-related fatigue and
not for sleep disorders, the authors note.
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One strength, however, is the inclusion of people with different
types of cancer, including blood malignancies, breast tumors and
gynecological cancers, noted Ilia Karatsoreos of the Sleep and
Performance Research Center at Washington State University in
Pullman. While some previous studies have found similar results with
bright light therapy for cancer survivors, research to date has
focused mostly on breast cancer, Karatsoreos, who wasn’t involved in
the study, said by email.
“What is new about this study is that it demonstrates that there is
potential for the use of bright light therapy to improve fatigue in
many different types of cancer, suggesting that potentially the
underlying mechanisms are similar in different disease states,”
Karatsoreos said.
Even without a light box, people may get enough bright light
outdoors and they may also improve sleep by eating well and
exercising regularly, noted Frida Rangtell, a sleep researcher at
Uppsala University in Sweden who wasn’t involved in the study.
“If patients do not have access to a light box, going outside and
getting natural light exposure in the morning or during the day can
exert similar effects,” Rangtell said by email. “If this is not
possible, it could be good to at least be as close to a window with
natural light exposure as possible, and keep the indoor lighting as
bright as possible during the morning.”
SOURCE: http://bit.ly/2rLWO2m Journal of Clinical Sleep Medicine,
online January 15, 2018.
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