Light therapy for managing cognitive, sleep, functional, behavioural, or psychiatric disturbances in dementia

Rest-activity and sleep-wake cycles are controlled by the endogenous circadian rhythm generated by the suprachiasmatic nuclei (SCN) of the hypothalamus. Degenerative changes in the SCN appear to be a biological basis for circadian disturbances in people with dementia, and might be reversed by stimulation of the SCN by light.

The review assesses the evidence of effectiveness of light therapy in managing cognitive, sleep, functional, behavioural, or psychiatric disturbances associated with dementia.

The Specialized Register of the Cochrane Dementia and Cognitive Improvement Group (CDCIG), The Cochrane Library, MEDLINE, EMBASE, PsycINFO, CINAHL and LILACS were searched on 4 March 2008 using the terms: "bright light*", "light box*", "light visor*", "dawn-dusk*", phototherapy, "photo therapy", "light therapy" "light treatment", light* . The CDCIG Specialized Register contains records from all major health care databases (The Cochrane Library, MEDLINE, EMBASE, PsycINFO, CINAHL, LILACS) as well as from many trials databases and grey literature sources.

All relevant, randomized clinical trials in which light therapy, at any intensity and duration, was compared with a control group for the effect on managing cognition, sleep, function, behavioural, or psychiatric disturbances (as well as changes in institutionalization rates or cost of care) in people with dementia of any type and degree of severity.

Three reviewers independently assessed the retrieved articles for relevance and methodological quality, and extracted data from the selected studies. Statistically significant differences in outcomes between the treatment and control groups at end of treatment and follow-up were examined. Each study was summarized using a measure of effect (e.g. mean difference).

Eight trials met the inclusion criteria. However, three of the studies could not be included in the analyses because of inappropriate reported study analyses or inability to retrieve the required data from the investigators. This review revealed no adequate evidence of the effectiveness of light therapy in managing cognition, sleep, function, behaviour, or psychiatric disturbances associated with dementia.

There is insufficient evidence to assess the value of light therapy for people with dementia. Most of the available studies are not of high methodological quality and further research is required.