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.
Color
Temperature
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.
Sources and Additional
Information:
