Photo by Petr Kratochvil
Sleeping woman
Results of a pilot study suggest that systematic bright light exposure can improve sleep in fatigued cancer survivors.
Subjects who were exposed to bright light every morning for 4 weeks had a significantly greater improvement in sleep efficiency than those who were exposed to dim light over the same period.
In fact, subjects in the bright light group were able to achieve clinically normal levels of sleep efficiency, and subjects in the dim light group were not.
Sleep efficiency is the percentage of time in bed that subjects spent sleeping.
Lisa M. Wu, PhD, of Northwestern University in Chicago, Illinois, and her colleagues reported these results in the Journal of Clinical Sleep Medicine.
The team noted that cancer patients report sleep disturbances at a significantly higher rate than the general population. Between 23% and 44% of cancer patients experience insomnia symptoms even years after treatment.
With this in mind, the researchers studied 44 individuals who had completed cancer treatment and met criteria for clinically significant fatigue at screening.
The subjects had an average age of 53.6, and 75% percent were female. Roughly 55% (n=24) had been diagnosed with a hematologic malignancy.
The subjects were randomized to a bright white light intervention or a dim red light intervention. Subjects in both treatment arms were provided with a light box and instructed to use it every morning for 30 minutes for 4 weeks. Sleep was evaluated using wrist actigraphy and the Pittsburgh Sleep Quality Index.
At baseline, 52.6% of subjects in the dim light group and 60% in the bright light group exceeded the clinical cutoff for poor sleep efficiency (≤ 85%). The mean sleep efficiency was 81.8% and 82.8%, respectively.
During the study period, sleep efficiency improved significantly more among subjects exposed to the bright light than those exposed to the dim light (P=0.003).
The mean sleep efficiency was in the clinically normal range for subjects in the bright light group at the end of the intervention (86.06%) and 3 weeks after (85.77%).
However, the cutoff for poor sleep efficiency was not reached in the dim light group, either at the end of the intervention (mean=79.35%) or 3 weeks after (mean=80.88%).
Total sleep time tended to increase over the study period for subjects in the bright light group, but there was no significant difference in total sleep time between the bright light and dim light groups.
Likewise, there was no significant between-group difference in waking after sleep onset, although this outcome tended to decrease over the study period for subjects in the bright light group.
“Systematic light exposure using bright white light is a low-cost and easily disseminated intervention that offers a feasible and potentially effective alternative to improve sleep in cancer survivors,” Dr Wu said.
However, she and her colleagues noted that larger-scale studies are needed.
