Phototherapy for patients with Alzheimer disease with disturbed sleep patterns: results of a community-based pilot study.

We examined the entraining effects of phototherapy delivered by light visors on disturbed sleep patterns of community-dwelling research subjects with Alzheimer disease (AD). The pilot project used a single subject design and activity monitoring as the primary outcome measures. The protocol consisted of a 5-day baseline monitoring period, followed by 10 consecutive days of phototherapy (2,000 lux of full spectrum bright light) delivered by light visors for 2 hours each morning; this was followed by an additional 14 days of activity monitoring. Cosinor analyses found no consistent changes in acrophase, mesor, or amplitude. Observed changes in acrophase were consistent with phase advancement of the rest-activity cycle and consistent with the biological intervention. Changes in the number of nighttime awakenings were not found. One subject had a significant increase in total sleep time, whereas another had a significant decrease in total sleep time. Failure to find a consistent biological effect of light on AD subjects may be secondary to: (1) insufficient duration of light exposure; (2) timing of light administration (given at a time when circadian rhythm is refractory to the effects of light); (3) advanced stages of AD making the Y circadian pacemaker in the suprachiasmatic nucleus of the hypothalamus insensitive to the biological effects of light; and (4) inadequacy of light visors as a means of providing light.