Importance of Light Management
Many researches confirmed beyond reasonable doubt that the natural progress of Alzheimer's disease in most patients results in damage to a part of the brain (the Suprachiasmatic Nucleus or SCN, where the master biological clock is located), which is central to circadian regulation of such behaviors as the sleep/wake cycle. The particular characteristics of this damage include phase advance and reduced period and amplitude, as well as an increased intra-daily variability and a decreased inter-daily stability of the rhythm. Among the factors underlying these changes the loss of SCN neurons seems to play a central role. Other contributory factors may be reduced amount of light, degenerative changes in the visual system and the level of activity and decreased melatonin.
Therefore, several sleep disturbances have been characterized as common for Alzheimer’s patients:
- Increased duration and frequency of awakenings.
- Decreased slow-wave sleep (SWS) and rapid eye movement (REM) sleep.
- Daytime napping.
It is estimated that in later years of the disease, patients spend approximately 40% of their time at night awake and a significant amount of their daytime hours asleep. This aperiodic pattern of behavior is very difficult for caregivers who must be vigilant to the needs of AD patients because they are usually on a normal, 24-hour, circadian pattern of rest and activity.
Clinical research has shown that exposure to very bright light in the day and darkness at night can consolidate rest and activity patterns in AD patients. So, disruption to the normal circadian rhythms can be reduced, making it more likely that the patient will be able to fit in with a normal daily sleep/wake cycle.
The combination of damaged nerve pathways caused by Alzheimer’s Disease and gradual deterioration of the eyes due to ageing, means that indoor levels of light are not usually sufficient to signal that it is daytime, so the patient’s internal body clock is not attuned to the usual daily pattern. This affects not only the wake-up processes at the beginning of the day but also the rest and sleep cycle that come into force in the evening.
Following one of the recent studies, the group of researchers concluded: "Sometimes the ability to control sleep disturbance can make the difference between keeping a loved one at home or in an institution. Too often we shut people with dementia up in dark rooms, with little opportunity to see the sun or other bright light, which can make their symptoms worse."
So, one of the characteristics that a circadian rhythm must have to be considered genuine is that it can be reset by an external stimulus. Each day the light/dark cycle and other environmental stimuli help maintain the rhythm so that it stays synchronous with the 24-hour day. If, however, the suprachiasmatic nucleus is destroyed completely, the sleep/awake cycle will be totally disrupted.
We should expect, then, that partial damage to the suprachiasmatic nucleus will effect sleeping patterns, not completely but to some extent. This is in agreement with the clinical findings: People with Alzheimer's disease and with other dementias, which results in shrinkage to that part of the brain, suffer more sleep disorders than otherwise healthy people of the same age.
An increasing amount of evidence shows that bright, full spectrum light, on the magnitude of 5000 LUX to 10,000 LUX, can reset the circadian rhythm in people suffering from Alzheimer's. Daily exposure to this type of light helps dementia patients with sleep disorders sleep longer and spend more time in deep sleep. As an added benefit, cognitive deterioration slowed with regular exposure to bright light, and symptoms of depression decreased.
White brightness is one of the pillars of the light therapy in dementias such as Alzheimer's, it is not the only factor should be taken in consideration. Researchers have found that the right color temperature and appropriate application timing can offer additional benefits in creating a positive impact on mood, behavior and even sundowning of the patients.
The following video presentation will show you the basics of the color temperature understanding:
A Wayne State University researcher found that getting the maximum therapeutic effects from exposure to light hinges on using the right shade of white light at the right time.
Cool White Light
Blue-green light was perceived by caregivers as having improved global functioning of patients, according to researcher LuAnn Nowak Etcher, Ph.D., assistant professor of nursing. Caregivers said patients receiving light-therapy treatments in the bluer parts of the spectrum showed noticeable improvements, including:
- Patients seemed more awake and alert
- People with dementia were more verbally competent
- Alzheimer's patients showed improved recognition, recollection and motor coordination.
- The patients seemed to recapture their personalities and were more engaged with their environment.
- Patients' moods also were described as improved.
Warm White Light
Warm light is white light with a red-yellow tinge to it. Although the experiment was meant to test the effects of blue-green light on dementia patients, to do so Dr. Etcher had to also have a placebo group that was exposed to red-tinged light. Dr. Etcher was surprised when some people in the placebo group, who were living with the red-tinged light, showed a variety of other improvements. In particular, caregivers reported:
- Patients were calmer
- People with dementia had reduced resistance to care.
Choosing Therapeutic Lights for Dementia
When one goes shopping for lamps, most have a "color temperature" on the label. This measure ranges from 2700K (short for 2700 degrees Kelvin) on the red-yellow end of the spectrum all the way to 6500K on the green-blue, or "daylight" end of the spectrum.
All the lamps give off white light, but there are different tinges. Think of a typical morning outdoors, as the sun rises until it reaches its zenith at high noon.
- 2700K lamps (also called warm white) simulate the kind of light we get outdoors towards sunrise or sunset. Though white, its tinge emanates a warm, sleepy feeling. This would explain the calming, mood improving effect described in the dementia patients above.
- 6500K lamps (also called daylight) simulate outdoor light at high noon, when the sky is intensely blue, the light is often called harsh and people are the most "awake." Given these characteristics, the cognitive improvements seen in the list above make perfect intuitive sense.
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