Alzheimer's, Dementia & Mental Health
Adding Bright Light in Long-Term Care Setting Seems
to Improve Dementia in Elderly
Adding melatonin also helps these senior citizens
sleep better
June 10, 2008 - The use of daytime bright lighting
to improve the circadian rhythm of elderly persons resulted in modest
improvement in symptoms of dementia, and the addition of melatonin
resulted in improved sleep, according to a study in the June 11 issue of
the Journal of the American Medical Association.
In elderly patients with dementia, cognitive
decline is frequently accompanied by disturbances of mood, behavior,
sleep, and activities of daily living, which increase caregiver burden
and the risk of institutionalization, the author write.
These symptoms have been associated with
disturbances of the circadian rhythm (the regular recurrence, in cycles
of about 24 hours, of biological processes or activities).
Impaired sleep is common in older persons and is
associated with poorer daytime function; greater risk of mood disorders;
poorer quality of life; impaired immune function; and greater rates of
falls, injuries, physician visits, and healthcare costs, according to a
2007 study that experimented with brighter light for dementia patients.
Sleep problems are particularly prevalent in
persons with Alzheimer's disease and related dementias, in whom
circadian rhythm disturbances and fragmented sleep are nearly universal.
Theoretically, high-intensity light therapy holds considerable promise.
It is known to be the major source of entrainment of the human circadian
system, according to the authors of that study, which was published in
the Journal of the American Geriatrics Society in November of 20007.
(See note below news report.)
The researchers then concluded that bright ambient
light in public areas of long-term care facilities can have modest but
measurable improvement on sleep patterns and circadian rhythms of
persons with dementia.
A circadian rhythm is an approximate daily period,
a roughly-24-hour cycle in the biochemical, physiological or behavioral
processes of living beings. The term "circadian", coined by Franz
Halberg, comes from the Latin circa, "around", and diem or dies, "day",
meaning literally "approximately one day."
The circadian timing system is highly sensitive to
environmental light and the hormone melatonin and may not function
optimally in the absence of their synchronizing effects. In elderly
patients with dementia, synchronization may be [diminished] if light
exposure and melatonin production are reduced, according to the authors
of the study in JAMA.
Rixt F. Riemersma-van der Lek, M.D., of the Royal
Netherlands Academy of Arts and Sciences, Amsterdam, and colleagues
conducted a trial at 12 elderly group care facilities in the Netherlands
that evaluated the effects of up to 3.5 years of daily supplementation
of bright light and/or melatonin on a number of health outcomes,
including symptoms of dementia and sleep disturbances.
The study included 189 facility residents, average
age 85.8 years; 90 percent were female and 87 percent had dementia.
Six of the facilities had bright lighting installed
in ceiling-mounted fixtures. Lights were on daily between approximately
9 a.m. to 6 p.m. Participants were randomized to receive evening
melatonin (2.5 mg) or placebo and participated an average of 15 months
(maximum period of 3.5 years).
The researchers found that bright light -
● lessened cognitive deterioration by a relative 5 percent,
● reduced depressive symptoms by a relative 19 percent and
● diminished the gradual increase in functional limitations by a
relative 53 percent.
Melatonin reduced the time to fall asleep by a
relative 19 percent and increased total sleep duration by 6 percent, but
adversely affected caregiver ratings of withdrawn behavior and mood
expressions.
The addition of bright light improved the adverse
effect on mood. In combination with bright light, melatonin reduced
aggressive behavior by a relative 9 percent.
In conclusion, the simple measure of increasing
the illumination level in group care facilities [improved] symptoms of
disturbed cognition, mood, behavior, functional abilities, and sleep.
Melatonin improved sleep, but its long-term use by elderly individuals
can only be recommended in combination with light to suppress adverse
effects on mood. The long-term application of whole-day bright light did
not have adverse effects, on the contrary, and could be considered for
use in care facilities for elderly individuals with dementia, the
authors write.
About Melatonin
In humans, melatonin is produced by the pineal
gland, a gland about the size of a pea, located in the center of the
brain. The melatonin signal forms part of the system that regulates the
circadian cycle by chemically causing drowsiness and lowering the body
temperature, but it is the central nervous system that controls the
daily cycle in most components of the paracrine and endocrine systems
rather than the melatonin signal (as was once postulated).
Light dependence
Production of melatonin by the pineal gland is
inhibited by
light and permitted by
darkness. For this reason melatonin has been called "the hormone of
darkness" and its onset each evening is called the Dim-Light Melatonin
Onset (DLMO). Secretion of melatonin as well as its level in the blood,
peaks in the middle of the night, and gradually falls during the second
half of the night, with normal variations in timing according to an
individual's
chronotype.
Until recent history, humans in temperate climates
were exposed to only about six hours of daylight in the winter. In the
modern world, artificial lighting reduces darkness exposure to typically
eight or fewer hours per day all year round. Even low light levels
inhibit melatonin production to some extent, but
over-illumination can create significant reduction in melatonin
production. Since it is principally blue light that suppresses
melatonin, wearing glasses that block blue light in the hours before
bedtime may avoid melatonin loss. Use of blue-blocking goggles the last
hours before bedtime has also been advised for people who need to adjust
to an earlier bedtime, as melatonin promotes sleepiness.
Melatonin levels at night are reduced to 50% by
exposure to a low-level incandescent bulb for only 39 minutes, and it
has been shown that women with the brightest bathrooms have an increased
risk for breast cancer.
Reduced melatonin production has been proposed as a
likely factor in the significantly higher
cancer rates in night workers, and the effect of modern lighting
practice on endogenous melatonin has been proposed as a contributory
factor to the larger overall incidence of some cancers in the developed
world.
Treatment of circadian rhythm disorders
Exogenous melatonin, used as a
chronobiotic and usually taken orally in the afternoon and/or
evening, is, together with
light therapy upon awakening, the standard treatment for
delayed sleep phase syndrome and
non-24-hour sleep-wake syndrome. See
Phase response curve, PRC. It appears to have some use against other
circadian rhythm sleep disorders, such as
jet lag and the problems of people who work rotating or night
shifts.
Learning, memory and Alzheimer's
Melatonin receptors appear to be important in
mechanisms of learning and memory in mice. Studies in rats suggest that
melatonin may be effective for treating Alzheimer's Disease. These same
neurofibrillary tangles can be found in the hypothalamus in patients
with Alzheimer's, adversely affecting their bodies' production of
melatonin. Those Alzheimer's patients with this specific affliction
often show heightened afternoon agitation, called sundowning, which has
been shown in many studies to be effectively treated with melatonin
supplements in the evening.
>>
More on Melatonin at Wikipedia
>>
About Circadian Rhythm at Wikipedia
2007 Study: High-Intensity Environmental Light
in Dementia: Effect on Sleep and Activity
From
Journal of the American Geriatrics Society
Philip D. Sloane, MD, MPH; Christianna S. Williams,
PhD; C. Madeline Mitchell, MURP; John S. Preisser, PhD; Wendy Wood, PhD;
Ann Louise Barrick, PhD; Susan E. Hickman, PhD; Karminder S. Gill, MSPH;
Bettye Rose Connell, PhD; Jack Edinger, PhD; Sheryl Zimmerman, PhD
Author Information
