ALTERNATIVE TREATMENTS FOR SLEEP MAINTENANCE
INSOMNIA IN THE ELDERLY: WHITE LIGHT VS GREEN LIGHT
Philip Gehrman1, Jennifer Martin1, and Sonia Ancoli-Israel2
1SDSU/UCSD Joint Doctoral Program in Clinical Psychology, 2Department of Psychiatry,
University of California, San Diego, San Diego VASDHS
Introduction: Insomnia, especially sleep maintenance insomnia, is a common sleep complaint in elderly individuals. People with this problem fall asleep fairly quickly, but suffer from frequent nocturnal and early morning awakenings with difficulty returning to sleep. One potential cause of this disorder is a phase advance of the circadian pacemaker (Czeisler et al., 1986). This phase advance may cause the individual to feel sleepy early in the evening and to wake up early in the morning. These individuals often force themselves to stay up until their desired bedtime, but awaken earlier than they would like due to the phase advance of the circadian pacemaker, thus leaving them with an insufficient amount of sleep. Insomnia has traditionally been treated with sedative-hypnotic medications which can have side effects and are not appropriate for long-term use. Campbell et al. (1993) found that bright light therapy (~ 4000 lux), which targets the circadian system, can improve sleep in older insomniacs. Our study sought to test a less intense bright white light ( ~ 2500 lux; Apollo Light Systems), as well as to compare the effectiveness of this treatment with green light ( ~350* lux; Sunnex Biotechnologies, Inc.). There is evidence from animal research that light in the blue-green spectrum has the strongest effect on the circadian system (e.g. Foster et al., 1993).
Methods: These data are part of a larger study on alternative treatments for insomnia. Seventeen individuals began the study. Two withdrew due to intolerance of the treatment. Complete Actillume (Ambulatory Monitoring, Inc.) and sleep diary information were available for 13 subjects (8 men, 5 women; mean age = 76.4 years, SD = 8.3, range = 61-88). Subjective self-report information was obtained using daily sleep logs. Subjects completed a five day baseline phase followed by 10 days of treatment with either bright white light or green light. Subjects were randomly assigned to one of the two treatments. Subjects sat within 1 meter of the light apparatus from 2000h to 2200h. Due to the small sample size at this point in the study, we examined the subjects case by case to look for evidence of improvement on both objective (time in bed, total sleep time, sleep efficiency, number of awakenings, and average awakening length) and subjective sleep parameters (time spent napping, sleep latency, number of awakenings, wake after sleep onset, total sleep time, and the times they went to bed, woke up, and got out of bed). Data from the baseline phase were compared to the last five days of treatment.
Results: Of the 13 participants, 6 received bright white light and 7 received green light. 2 of the 6 (33 %) white light subjects and 4 of the 7 (57 %) of the green light subjects showed improvement on at least half of the sleep parameters examined. Those subjects who improved had Actillume data that showed a decrease in the total amount of time spent in bed, an increase in sleep efficiency, and fewer nocturnal awakenings. On their sleep diaries, they reported increased total sleep time, decreased wake after sleep onset, and fewer awakenings. They also reported being able to stay awake later at night and sleep until later in the morning.
Discussion: Although these results are preliminary and there is insufficient power to examine statistical analyses, these findings suggest that bright white and green light may be effective treatments for this group. The green light was effective in a larger percentage of subjects when compared to white light. Some subjects complained of the intensity of the white light. The green light has less glare, so the greater effectiveness of this treatment may be due to the subjects having greater tolerance and therefore being more compliant. In general, people who showed improvement objectively also reported subjective improvement, while those who did not show objective improvement did not report improved sleep. This provides some criterion-related validity to both Actillume and sleep diary indices of sleep in insomnia patients. The effectiveness of circadian interventions supports the hypothesis that circadian factors contribute to the etiology of insomnia. These findings strengthen the argument for the use of non-pharmacologic interventions for the treatment of sleep-maintenance insomnia in the elderly. Additional subjects are needed to further investigate these results.
Czeisler, C.A. et al. (1986) Sleep Res. 15:268.
Campbell, S.S. et al. (1993) J. Am. Geriatr. Soc. 41:829-836.
Foster, R., et al. (1993) J. Biol. Rhythms 8:S17-S23.
* corrected from original abstract, which was misstated as (~ 2500 lux)