Right Lighting Boosts Sleep For Alzheimer’s Patients

- May 05, 2019-

People with Alzheimer’s disease and related dementias commonly experience sleep problems, wandering, and daytime irritability. This study tested whether a tailored daytime lighting installation could improve sleep and behaviour in Alzheimer’s patients living in long-term care facilities.

Compared to baseline and to the inactive lighting condition, the lighting significantly decreased sleep disturbances, depression and agitation. While all measures improved, the most significant improvement was seen in sleep quality.

‘Here we show that if the stimulus [light dose] is carefully delivered and measured, it can have a strong impact on sleep, depression and agitation,’ principal investigator and lead author Mariana Figueiro, PhD, a professor and director at the Lighting Research Center at Rensselaer Polytechnic Institute in New York, told Lux. ‘Depression was a secondary measure, and I was pleasantly surprised by the positive impact of the light treatment on depression scores.’

The study involved 43 subjects diagnosed with Alzheimer’s disease and related dementias who were exposed to an active and inactive tailored lighting intervention for successive four-week periods, spaced by a four-week ‘washout’ period.

The lighting – a tuned and dynamic colour temperature, output and distribution to achieve a medium ‘circadian stimulus’ of 0.3 – was added to spaces in which patients spent most of their waking hours and was energised from wake time until 6 pm. Calibrated personal light meters monitored exposures. Measures of sleep disturbances (Pittsburgh Sleep Quality Index), mood (Cornell Scale for Depression in Dementia) and agitation (Cohen-Mansfield Agitation Index) were collected at baseline and during the last week of the special lighting.

An example of circadian stimulus, from the Rensselaer Polytechnic Institute in New York. It’s based on a mix of the colour temperature, output and the amount of such light hitting the cornea of the patients. The circadian stimulus in this study was CS 0.3.