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Circadian Rhythm Disorders in Patients Suffering from Alzheimer’s Disease

Circadian rhythms allow the body to time its different processes such as sleeping, waking up, and eating. These rhythms follow a 24-hour schedule that is in accordance with nature’s day-night cycle. For instance, the setting of the sun and the dimming of lights trigger the body to release certain hormones that induce sleep. Problems with the circadian system can arise due to dysfunctions of the circadian clock and changes in lifestyle and external schedules.

Studies have shown that the circadian functioning deteriorates with aging. However, in patients with Alzheimer’s disease, these changes and deteriorations are much more pronounced.  Sleep and behavioral changes associated with Alzheimer’s disease include restlessness, agitation during the waking hours, and difficulty in sleeping during night time.

Patients with Alzheimer’s Disease May Experience Several Circadian Rhythm Problems

Causes of Circadian Rhythm Disorders in Patients with Alzheimer’s Disease

The main cause of circadian rhythm disorders in patients suffering from this neurodegenerative illness is the alterations in the suprachiasmatic nucleus (SCN) which, in turn, affects melatonin secretion. The SCN, which is the control center of the circadian rhythms in mammals, contains the inhibitory neurotransmitters gamma-aminobutyric acid (GABA) and arginine vasopressin (AVP) that send inhibitory impulses to the paraventicular nucleus in the hypothalamus. This action leads to the release of melatonin from the pineal gland. The amount of melatonin secretion increases 2 hours before bedtime and stays at elevated levels throughout the night.

Another explanation for the occurrence of circadian rhythm disorders in patients with Alzheimer’s disease is the degenerative changes that take place in the brain. Alzheimer’s disease can cause damage to parts of the brain that are responsible for putting a person in the REM stage of sleep. Studies reveal that Alzheimer’s disease patients stay longer in the first stage of sleep but spend less time on the REM stage. Hence, these patients do not experience deep slumber and are easily awakened by petty noises and movements.

Circadian Rhythm Problems of Patients with Alzheimer’s Disease

In older people, the circadian problem that is more prevalent is the advanced sleep phase syndrome but this is not always the case with Alzheimer’s disease patients. Some of them may experience insomnia, hypersomnia, sundowning, and REM sleep behavior disorder.

Treatment Methods for Alzheimer’s Disease Patients with Circadian Rhythm Disorders

Two of the most utilized treatment methods for the alleviation of sleep-wake problems in patients with Alzheimer’s disease are the behavioral and environmental therapy and the administration of medications.

  • Environmental and Behavioral Approaches – Changes in the patients’ external schedule may be employed to normalize the functioning of the circadian system. These include setting a regular schedule for meals and bedtime. The noise levels can also be minimized to prevent the disruption of the patients’ sleep. Adjustments in the brightness of lighting can be made depending on what their circadian rhythm problem is. Performance of physical activities can help normalize their circadian rhythms because this increases blood pressure and reduces daytime sleepiness which can disrupt the normal sleep-wake cycle.
  • Medications – Numerous medications can be prescribed and again, the prescription is determined by the type and severity of the circadian rhythm problem. Some drugs treat insomnia, hypersomnia, agitation, restless leg syndrome, and REM problems. It would be best to administer these medications in conjunction with environmental and behavioral therapy. These medications should be prescribed by a doctor to prevent further complications in the illness of the patients.