Sleep Disorders in Dementia

What are normal sleep pattern changes in older age?

The amount of sleep we need varies over the course of our lifetime. Such variations depend on your age and general health as well as lifestyle habits. For instance, during periods of stress or illness, you may feel an increased need for sleep.

Sleep changes may become more evident in older adults. Changes in the basic structural organisation of normal sleep are noticeable (e.g., change in biological clock drive). Some of these changes are apparent, and some are not: shifts in our natural predisposition to fall asleep, sleeping fewer hours per night, awakening during the night (wake after sleep onset) and waking up earlier than usual. 

Other changes include:

  • Sleep latency (SL) refers to the time it takes for us to fall asleep
  • Sleep fragmentation, or the transformation of the different cycles of sleep (Rapid Eye Movement (REM) and Non-REM sleep) into shorter, discontinued periods
  • Decrease in REM sleep  

Older adults also have circadian rhythms that synchronise less efficiently to their environment than younger people, meaning they have more variable sleep/wake patterns. In other words, there is an overall decrease in the stability of our sleep as we age, and sleep becomes less efficient (sleep efficiency) at providing positive health effects. 

Sometimes these sleep changes may lead to excessive daytime sleepiness (EDS) or circadian rhythm sleep disorder (CRSD) and can become more dramatic in dementia patients.

Although the normal age-related changes above parallel some of the sleep challenges seen in people with dementia, the sleep pattern changes in dementia patients tend to be more dramatic and disruptive. 

How does sleep affect dementia risk?

Sleep disturbances, specifically deep-sleep fragmentation (N-REM sleep), are a known factor in increasing the potential of developing dementia. It increases cellular stress and inflammation and affects the clearing of the byproducts of the brain's cellular oxidative stress. This leads to an increase in amyloid and tau proteins which can lead to the development of dementia (SEE ARTICLE: Dementia Risk Factors). Indeed, a meta-analysis of sleep disturbances referred to above (more specifically: EDS, CRSD, or others such as sleep disorder of breathing) indicates that such issues can predict the risk of developing dementia.1

How does dementia change these sleep patterns?

Sleep disturbances are often brought up by the breakdown of the suprachiasmatic nucleus (SCN): an important circadian pacemaker which regulates the rhythm and synchronicity of our biological clocks. 

The reduction of melatonin secretion is also another well-known issue. As melatonin production in the pineal gland essentially acts as an endogenous circadian pacemaker, the reduction of its production, associated with a dysregulation of melatonin receptors in the SCN, further increases dementia-related sleep disturbances. 

Moreover, the ventrolateral preoptic area (VLPO) in the anterior hypothalamus, considered a key area for sleep initiation and maintenance, is also affected, leading to sleep fragmentation.

The consequences are that the sleep/wake alterations described above are increased in dementia. Patients with dementia can go to bed earlier and wake up later than non-dementia sufferers of the same age, and SL rises even further, with people with dementia taking even longer to fall asleep.

Do all dementia patients experience sleep pattern changes?

Sleep/wake disturbances are considered hallmark symptoms of dementia. Sleep pattern changes affect 39% of dementia patients, or more than 70% of patients when all sleep disorders associated with dementia are included.2 Other studies have indicated that 60% to 70% of people with cognitive impairment or dementia have sleep disturbances.3

Dementia patients can express sleep disturbances from the early stages of the disease, with some studies suggesting that these changes may even be present as early as 3 to 5 years before diagnosis. Hence, a preventive strategy, more specifically associated with sleep problems in middle-aged and older adults, is to identify and treat sleep problems to prevent future cognitive decline and dementia. 

Are there any risk factors associated with the development of dementia?

As people age, some will experience increased sleep latency, leading them to use sleeping drugs such as benzodiazepines. Concerns have been raised by studies indicating that the repetitive or long-term use of such drugs could lead to cognitive function impairments, with some studies indicating the potential for permanent deficits.4,5,6 

What can help someone with dementia sleep better?

Light therapy exposure, increased daytime physical activity, proper feeding (e.g., not eating late at night) and melatonin intake, as a combined therapeutic approach, are all effective at regulating sleep in healthy ageing adults. Providing that patients with dementia onset are still cognitively capable of performing such activities, these treatments might lead to better sleep. 

Melatonin, more specifically, has been associated with slowing down brain cell deterioration (neuroprotective). It not only synchronises peripheral organ rhythms (e.g., kidneys, liver, etc), and as such allows for the organisation of the biological clock and the better function of peripheral organs conferring a host of protective effects. Cumulative evidence suggests that melatonin has a wide range of neuroprotective roles by regulating pathophysiological mechanisms and signalling pathways.8 

A review by the American Academy of Neurology, investigating the management of dementia, has reported that cholinesterase inhibitors might benefit patients with dementia.7 Although such drugs are normally used to avoid loss of cognitive decline, they may equally increase REM sleep, which may be impaired in dementia.

Behavioural interventions are a safe and effective option for treating sleep disturbances in dementia patients.

What are the sleep challenges for dementia patients?

People with sleep disorders can suffer from increased restricted activities of daily living, and poor quality of life can be especially more pronounced if breathing disturbances and insomnia are reported. Such disruption can bring further social isolation, and sleep disruption may contribute to symptoms of depression.

What are other sleep disorders common in people with dementia?

Dementia patients can present with REM sleep behaviour disorder (RBD). RBD is a condition associated with REM sleep, where patients have an unregulated motor function. This leads to no longer having the normal paralysis you experience in the REM sleep state and can lead to excess movement and talking whilst sleeping. However, studies have indicated that such disorders usually don’t show until 10 to 15 years post dementia onset.3

“Sundowning” may also happen. Sundowning is a phenomenon in which individuals with dementia experience increased agitation later in the day and in the evening and may impact sleep. 

What are the symptoms of REM sleep Behaviour Disorder (RBD)?

Affected patients with dementia can express extreme motor activity during REM sleep, such as punching, kicking, or crying out.

Symptoms and causes of sundowning in people with dementia

Sundowning is an observable behaviour causing agitation in dementia patients. This behaviour is associated with disturbed sleep as well as increased activity during the evening. It is common for dementia patients to experience sundowning; but the problem is that such behaviour may have delayed consequences on sleep patterns. If sundowning occurs, a person may feel sleepier earlier and more tired later in the evening than usual. This can lead to social isolation, which further leads to sleeping disturbances (inconsistent sleep patterns).

Possible causes of sundowning may be associated with circadian rhythm disorders that occur in dementia and seem to be linked with the degeneration of the cholinergic nucleus basalis Meynert (NBM), which are neurons that are suggested to promote the rest-activity disturbance during Sundowning.

The amount of sleep we need varies over the course of our lifetime; sleep changes may become more evident in older adults. Furthermore, the sleep pattern changes in dementia patients tend to be more dramatic and disruptive. There are different methods that can help patients with dementia sleep: light therapy exposure, increased daytime physical activity, proper feeding (e.g., not eating late at night) and melatonin intake, as a combined therapeutic approach.

References

  1. Shi L, Chen S-J, Ma M-Y, Bao Y-P, Han Y, Wang Y-M, et al. Sleep disturbances increase the risk of dementia: A systematic review and meta-analysis. Sleep Medicine Reviews 2018;40:4–16. https://doi.org/10.1016/j.smrv.2017.06.010
  2. Malkani RG, Zee PC. Sleeping well and staying in rhythm to stave off dementia. Sleep Med Rev 2018;40:1–3. https://doi.org/10.1016/j.smrv.2018.01.007
  3. Wennberg AMV, Wu MN, Rosenberg PB, Spira AP. Sleep Disturbance, Cognitive Decline, and Dementia: A Review. Semin Neurol 2017;37:395–406. https://doi.org/10.1055/s-0037-1604351
  4. Crowe SF, Stranks EK. The Residual Medium and Long-term Cognitive Effects of Benzodiazepine Use: An Updated Meta-analysis. Arch Clin Neuropsychol 2018;33:901–11. https://doi.org/10.1093/arclin/acx120
  5. Penninkilampi R, Eslick GD. A Systematic Review and Meta-Analysis of the Risk of Dementia Associated with Benzodiazepine Use, After Controlling for Protopathic Bias. CNS Drugs 2018;32:485–97. https://doi.org/10.1007/s40263-018-0535-3
  6. Picton J, Marino A, et al. Benzodiazepine use and cognitive decline in the elderly, American Journal of Health-System Pharmacy, Volume 75, Issue 1, 1 January 2018, Pages e6–e12, https://doi.org/10.2146/ajhp160381
  7. Doody RS, Stevens JC, Beck C, Dubinsky RM, Kaye JA, Gwyther L, et al. Practice parameter: management of dementia (an evidence-based review). Report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology 2001;56:1154–66. https://doi.org/10.1212/wnl.56.9.1154
  8. Chen, D., Zhang, T.,  Lee, T. H. 2020. Cellular Mechanisms of Melatonin: Insight from Neurodegenerative Diseases. Biomolecules, 10.

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Rodrigo Montenegro

Master of Science - MSc. Neuroscience, Universidad Isabel I, Spain

Rodrigo Montenegro is a Neuroscientist with Sleep Medicine specialization from Oxford University. Rodrigo has worked as a lead Neuroscientist developing a clinical grade sleep-headband and as a consultant in applied medical neuromodulation technologies.

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