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Effect of timed bright light treatment for rest‐activity disruption in institutionalized patients with Alzheimer's disease
Author(s) -
Dowling Glenna A.,
Mastick Judy,
Hubbard Erin M.,
Luxenberg Jay S.,
Burr Robert L.
Publication year - 2005
Publication title -
international journal of geriatric psychiatry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 129
eISSN - 1099-1166
pISSN - 0885-6230
DOI - 10.1002/gps.1352
Subject(s) - actigraphy , circadian rhythm , morning , rhythm , medicine , analysis of variance , psychology , audiology
Background Disturbances in rest‐activity rhythm are prominent and disabling symptoms in Alzheimer's disease (AD). Nighttime sleep is severely fragmented and daytime activity is disrupted by multiple napping episodes. In most institutional environments, light levels are very low and may not be sufficient to entrain the circadian clock to the 24‐hour day. Method The purpose of this randomized clinical trial was to test the effectiveness of timed bright light therapy in reducing rest‐activity (circadian) disruption in institutionalized patients with AD. The experimental groups received either morning (9.30–10.30 am) or afternoon (3.30–4.30 pm) bright light exposure ( ≥ 2500 lux in gaze direction) Monday through Friday for 10 weeks. The control group received usual indoor light (150–200 lux). Nighttime sleep, daytime wake, and rest‐activity parameters were determined by actigraphy. Repeated measures analysis of variance was employed to test the primary study hypotheses. Results Seventy institutionalized subjects with AD (mean age 84) completed the study. No significant differences in actigraphy‐based measures of nighttime sleep or daytime wake were found between groups. Subjects in either experimental light condition evidenced a significantly ( p < 0.01) more stable rest‐activity rhythm acrophase over the 10‐week treatment period compared to the control subjects whose rhythm phase delayed by over two hours. Conclusions One hour of bright light, administered to subjects with AD either in the morning or afternoon, did not improve nighttime sleep or daytime wake compared to a control group of similar subjects. However, exposure to one‐hour of bright light in either the morning or afternoon may provide sufficient additional input to the circadian pacemaker to facilitate entrainment to the 24‐hour day. Copyright © 2005 John Wiley & Sons, Ltd.