Full Spectrum Lights for Better Sleep
Sometimes simple therapies are the best. A good example is light therapy for Alzheimer’s. Alzheimer’s disease and other types of dementia affect the brain in a way that can cause sleep disturbances. We all know how we feel when we have a sleepless night. We’re cranky, we’re unsocial, and all we want to do the next day is nap.
Very often doctors prescribe medicine for sleep disorders, and drugs do sometimes help. But people with dementia are often over-medicated to begin with. Prescribing more medicine increases the likelihood of drug interactions, and sleep medicines often cause other problems. The Alzheimer’s Association makes this recommendation:
The risks of sleep-inducing medications for older people who are cognitively impaired are considerable. They include increased risk for falls and fractures, confusion, and a decline in the ability to care for oneself. If you find it necessary to use sleep medications, discontinue them after a regular sleep pattern has been re-established.
Most people function on a wake-sleep cycle that corresponds to our 24 hour day. The mechanism that controls that cycle is known as circadian rhythms. Anyone can have that cycle interfered with, resulting in sleep disturbances that are usually very temporary. Jet-lag is a good example of an event that can cause such a disruption; one that many of us have experienced. Getting over jet-lag is usually just a matter of letting your brain adjust to the new time zone. The day-night cycle is mostly responsible for that adjustment, responsible for resetting your circadian rhythms.
Sleep disorders are often associated with Alzheimer’s disease. Insomnia and the related daytime sleepiness are two symptoms that a person with Alzheimer’s often experiences. Sundowning is another. Sundowning is an increased agitation that occurs in the evening and is often accompanied by wandering. Sleep disorders of this type are not a minor problem. It imposes an added burden on a care-partners already difficult position, and wandering can be dangerous and even fatal. Unfortunately, the disruption in the circadian rhythms of a person who has Alzheimer’s disease is not as easy to fix as jet-lag. It doesn’t result from a vacation or business trip, but from brain damage caused by the disease.
Circadian Rhythms and the Suprachiasmatic Nucleus
The suprachiasmatic nucleus (SCN) is the part of the brain that controls circadian rhythms. The SCN is located within the hypothalamus, in the base of the brain. The hypothalamus is that part of the brain that is usually affected first by Alzheimer’s disease (read more….). Researchers at the Netherlands Institute for Brain Research found a marked decrease in the total cell mass of the suprachiasmatic nucleus in older people (80 to 100 years), and an even more pronounced reduction in people with Alzheimer’s disease (mean age 78). This shrinkage could account for the sleep disorders that many people experience as they age (waking in the night or too early in the morning, daytime napping, etc.). These and other disorders common in the elderly are more common and more pronounced in people with Alzheimer’s disease and many other dementias.
There is a direct connection between the eye and the suprachiasmatic nucleus. To make a long story short, light plays a big role in maintaining our circadian rhythms, and light can be used to reset those rhythms when they get out of kilter. The use of light therapy for Alzheimer’s disease can help lessen the sleep disorders that can be so much a part of that and other types of dementia.
Bright Light Therapy for Alzheimer’s Disease
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 expectation is in agreement with the clinical findings: People with Alzheimer’s disease and with other types of dementia that result 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.
Red light is not the same as full-spectrum (white) light. Full spectrum light contains the blue wavelengths, as well as all other visible wavelengths. The findings of this pilot study are consistent with others that have investigated the effects of bright, white light.
Special note: Researchers have found limited evidence that bright and blue light therapy may cause additional harm to people with pre-existing eye damage (including glaucoma and macular degeneration), and could increase the incidence of age related blindness. Medical professionals recommend people with pre-existing retinal conditions should be tested prior to using any bright or blue light therapy system.
Related Research for Light Therapy for Alzheimer’s Disease
Burns and Byrne, in a study reported in the British Medical Journal, found that dementia patients who sat in front of a bright (10 000 lux) light for two hours each morning slept an average of 40 minutes longer, and slept more deeply, than usual. A control group who sat in front of a one hundred lux light slept only about 8 minutes longer. This tendency was not evident during the summer, but the findings can be instructive for the long dark months of winter
A Dutch group reported in the June 11, 2008 issue of JAMA that bright light therapy “ameliorated symptoms of disturbed cognition, mood, behavior, functional abilities, and sleep.” The study was defined to investigate the combined effect of bright light therapy combined with melatonin. Based on the study the researchers conclude that:
…the simple measure of increasing the illumination level in group care facilities ameliorated 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.