Dementia And Sleep: Understanding The Complex Relationship

Sleep disturbances are common in people with dementia, with one study suggesting that between a quarter and half of older adults with Alzheimer's disease and other dementias suffer from some form of sleep disruption. The changes in brain function caused by dementia can affect the body's circadian rhythm, making it harder for people with the condition to fall asleep at night and often leading to excessive daytime sleepiness. This can be distressing for both patients and their caregivers.

There are several reasons why dementia patients may experience sleep disturbances. Changes in the brain can disrupt the body's circadian rhythm, making it difficult for patients to distinguish between night and day. Additionally, specific types of dementia, such as Lewy-body dementia and Parkinson's disease dementia, are associated with REM sleep behaviour disorder, which can make it challenging for patients to fall back asleep after waking up from a dream.

Certain medications used to treat dementia can also cause night-time stimulation and dream disturbances, further disrupting sleep patterns. Furthermore, pain within the body, particularly joint pain, is a common part of advanced ageing and can contribute to nocturnal sleep disorders in older patients with dementia.

Other factors that can impact sleep include light disturbances in the sleeping area, napping during the day, and underlying medical conditions such as sleep apnea and restless leg syndrome. Understanding these factors is crucial for caregivers to help improve sleep patterns in dementia patients and enhance their overall quality of life.

Circadian rhythm disruption

As a result, people with dementia may sleep excessively during the day and sleep less at night. This disruption can be further exacerbated by changes in their sleep structure. Typically, a healthy sleep cycle includes light sleep, deep sleep, and REM sleep. Deep sleep and REM sleep are critical for restoring the body and mind. However, people with dementia spend less time in these crucial stages of sleep, and this reduction can worsen as dementia progresses.

The disruption to the circadian rhythm can be influenced by various factors. One factor is the impact of specific types of dementia, such as Lewy-body dementia and Parkinson's disease dementia, which are associated with REM sleep behaviour disorder. Waking up from a dream can be especially confusing for people with dementia, as they find it challenging to distinguish between the dream and reality, making it harder to fall back asleep.

Additionally, the production of the sleep hormone melatonin may be affected by dementia. As the condition progresses, the brain may produce less melatonin, making it more difficult for individuals to fall asleep in the evening. This issue can be compounded by damage to the body clock, causing melatonin levels to fluctuate irregularly.

Furthermore, environmental factors, such as light disturbance in the sleeping area, can contribute to circadian rhythm disruption. Leaving lamps or landing lights on can cause confusion about whether it is night or day, leading to nighttime wandering. Maintaining a dark environment in the evening and exposing individuals with dementia to bright light or natural sunlight during the day can help regulate their sleep-wake cycle.

In summary, circadian rhythm disruption in people with dementia is caused by a combination of brain changes, specific types of dementia, altered hormone production, and environmental factors. These factors collectively impact their ability to maintain a healthy sleep-wake cycle, resulting in excessive daytime sleepiness and fragmented nighttime sleep.

Sleep-wake cycle changes

The suprachiasmatic nucleus (SCN), the part of the brain that serves as our internal clock, is often damaged in people with Alzheimer's disease, the most common type of dementia. This results in patients being unable to follow a 24-hour sleep-wake cycle and instead sleeping excessively during the day and less at night.

Additionally, dementia is associated with changes in sleep structure. People with dementia spend less time in slow-wave sleep and REM sleep, which are critical for restoring the body and mind, and more time in the earlier stages of sleep. This reduction in deep sleep and REM sleep can worsen as dementia progresses.

Dementia can also affect the production of melatonin, a sleep hormone in the brain that helps the person feel sleepy when it gets darker in the evening. As a person's dementia progresses, their brain may make less melatonin, making it harder to fall asleep at night. This can be exacerbated by damage to the person's body clock, which can cause melatonin levels to rise at the wrong time.

Furthermore, specific types of dementia, such as Lewy-body dementia and Parkinson's disease dementia, are associated with REM sleep behaviour disorder, which can make it especially confusing for people with dementia to wake up from a dream. Distinguishing between the dream and reality becomes more difficult, which can make it harder to fall back asleep.

Medication side effects

Additionally, there is growing concern that a specific class of medications, including Elavil (Amitriptyline), Benadryl (found in many OTC sleep aids), Doxepin (Sinequan, Silenor), Hydroxyzine (Vistaril, Atarax), Seroquel (Quetiapine), and Trimipramine (Surmontil), can increase the risk of dementia. These drugs block a brain chemical called acetylcholine (ACTH), which is critical for learning and memory. The more of these drugs a person takes, the higher their anticholinergic burden (ACB) score, and consequently, the higher their risk for dementia.

Furthermore, medications prescribed to improve dementia symptoms, such as donepezil, rivastigmine, or galantamine, can also cause insomnia as a side effect. These drugs can lead to vivid dreams and nightmares, and taking them in the morning instead of at bedtime may provide some relief. Other medications, such as those for anxiety, depression, allergies, and bladder control, can also increase the anticholinergic burden and contribute to sleep issues in dementia patients.

While there are drugs that can help induce sleep, they often come with unpleasant or dangerous side effects, such as dizziness and an increased risk of falls, making them less suitable for dementia patients. Melatonin is sometimes recommended as a safer alternative, but more evidence is needed to understand its long-term impact on health.

Daytime napping

Excessive daytime napping is frequently observed in older adults, especially those with Alzheimer's disease. A proposed mechanism for this is arousal deficiency, caused by neuronal and neurotransmitter loss in wake-promoting neurons, which results in sleep-wake disturbances and increased daytime sleepiness. Additionally, excessive sleepiness during the day has been linked to faster cognitive decline and Alzheimer's pathology.

Longitudinal studies have found that older adults tend to nap longer and more frequently as they age. This change is accelerated by the progression of Alzheimer's dementia, with the annual increase in nap duration and frequency more than doubling after a diagnosis of mild cognitive impairment or Alzheimer's disease. As such, excessive daytime napping is associated with a higher risk of developing Alzheimer's dementia.

It is important to note that the relationship between daytime napping and Alzheimer's dementia is complex and may be influenced by various factors. Daytime napping may be a result of poorer health or other medical comorbidities that are also associated with an increased risk of Alzheimer's dementia. Additionally, changes in the 24-hour circadian control and sleep-wake cycles may also contribute to this relationship.

While the exact mechanisms underlying the link between daytime napping and Alzheimer's dementia require further study, the available research suggests that excessive daytime napping may be a useful indicator of cognitive decline and a potential risk factor for Alzheimer's disease.

Pain and discomfort

Untreated pain can cause patients to become more withdrawn or fatigued due to discomfort and a lack of solid sleep. Even though patients may feel drowsy and sleep more than before, their sleep is disturbed and not restorative. Once their pain is treated, patients may become more alert and interactive, even if the medication has a possible side effect of drowsiness.

Chronic pain, lasting longer than three months, is associated with cognitive, emotional, and social decline in dementia patients. It affects some of the same areas of the brain as Alzheimer's disease, such as the locus coeruleus, which releases the chemical messenger norepinephrine, causing the pain-relaying cells in the brain to become inflamed. The degree of cognitive decline in a patient with Alzheimer's can be directly correlated with the severity of the pain experienced.

Other causes of pain in dementia patients include previous injuries and areas of surgery, which can become painful as patients become less mobile. Joints can become stiff and sore when not used regularly, and patients may avoid being repositioned or using painful body parts, leading to contractures, or the tightening of muscles, skin, tendons, and tissues. Pressure ulcers can also develop from spending a significant amount of time in the same position.

Mental pain can also be exacerbated by dementia. Patients may experience significant loss or grief, leading to social, spiritual, or emotional pain, which is felt physically like other types of pain.

To assess pain in patients with moderate to severe dementia who are unable to verbally express or rate their pain, the Pain Assessment in Advanced Dementia Scale (PAINAD) can be used. This scale helps to reduce the likelihood that pain will go unrecognized and untreated. It can be easily learned and used by people without prior medical training and does not require the patient to have language skills.

Non-medication treatments for pain in dementia patients include massage, music therapy, aromatherapy, pet therapy, and drawing. Massage can help ease pain and relax the body, even if the patient is unable to verbally communicate that it feels good. Music therapy can distract patients and release natural endorphins to reduce pain, as well as help orient patients and bring pleasant feelings and memories.

Repositioning is also important for managing pain and improving comfort. Frequent position changes enhance comfort, improve blood flow to the skin, and protect against pressure sores.

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