Tag Archives: sleep and memory

Sleep and aging

Sleep changes dramatically over our life spans.  As we know, newborns sleep the majority of the day and napping persists until age 3-4.  Eventually, our sleep consolidates into a single period of sleep lasting 7-8 hours per night.  Elderly individuals seem to be more prone to distressing sleep disruptions.  This blog post reviews the types of sleep issues that commonly occur as we age.

The effect of age on sleep

We have discussed the effects of decreased sleep on the elderly, and now we shall focus on what the effect a person’s age has on sleeping patterns.

A study has shown that elderly people experience a shorter duration of sleep time, decreased sleep efficiency, and increased waking up at night independent of other factors such as chronic conditions and problems such as sleep apnea.8

The study further found that in men, age was independently associated with more Stage 1 and Stage 2 sleep and less Stage 3 to 4 (slow wave sleep) and REM sleep. Older women were found to have more trouble falling asleep, and experienced more issues with waking up during the night and waking up too early.

Lack of sleep and dementia

One of the vital roles of sleep is to allow the brain to activate a specific system that is responsible for cementing long term memories in the brain cortex. Sleeping also helps individuals to retain information and perform better on memory tasks and activities.1

Studies have shown that sleep deprivation may be linked to the development of dementia disorders, such as Alzheimer’s disease, in the elderly.2 The reason behind this may be due to lack of slow-wave sleep causing the build-up of beta-amyloid proteins in the brain, which ultimately affect the mentioned system responsible for memory consolidation. Alzheimer’s disease also worsens patients’ sleep patterns, so a vicious cycle develops where sleep deprivation causes worsening of the disease which worsens the patients’ abilities to sleep.

Lewy body dementia, which is caused by deposits of Lewy body proteins on the nerve cells of the brain, directly causes increased daytime sleepiness due to lack of sleep.3 This seems to occur regardless of other factors such as disease progression and memory fluctuations in these affected individuals. Lewy body dementia is also responsible for rapid eye movement (REM) sleep disorder, which is a condition characterized by flailing of the limbs and acting out while dreaming. The reason for this is because REM sleep causes temporary paralysis of the skeletal muscles of the body, and REM sleep disorder inhibits this paralysis causing the patients’ symptoms.4

The researchers of these studies have collectively requested that further investigations are conducted into the cause and effect of sleep disturbances on dementia-related pathologies, in order to try and discover possible treatments for the conditions.

Sleep duration and inflammation

A recent study was done determining the link between the duration of sleep in the elderly and what effect inflammation has on the mortality of individuals aged between 71 and 76 years of age.5 The fundamental findings made were that short sleep duration (5 or less hours of sleep per night) was associated with an increase in inflammatory markers resulting in elevated mortality levels, and that longer sleep duration was associated with decreased mortality. These findings were made independent of other risk factors such as smoking, obesity, chronic conditions such as hypertension (high blood pressure) and diabetes (uncontrolled high glucose levels), and complications of these factors such as coronary artery disease.

Therefore, shorter sleep duration is regarded as an independent cause of increased mortality, thereby making this aspect just as detrimental to one’s health as the mentioned factors.

Sleep disturbances and depression

A study that was performed on a community of elderly people yielded that these individuals’ disturbed sleeping patterns were linked to them experiencing varying symptoms of depression.6

The sleep-related issues were linked to those who were female, living alone, unmarried and who had a disability. The two year follow up analysis of these elderly individuals showed that half of the participants still experienced sleep disturbances. It was discovered that the best predictors for future depression were elderly people with sleep disturbances and current depression symptoms; and for those who were not initially depressed, it was sleep disturbances alone.

This latter finding suggests that disturbed sleeping patterns are not only a symptom of depression, but rather as a possible predictor of the future development of depression in the elderly.

Sleep disorders and falls in the elderly

Since sleep-related disorders and falls are a common problem in the elderly, researchers decided to look into the possible link between the two problems.

Surveys were conducted which were filled in by elderly people between 65 and 89 years of age, and most of the participants admitted to falling down when getting up at night. The reason for the latter issue was that the individuals were experiencing poor sleep quality.7 Other risk factors for the falls included the use of diuretics, causing the affected participants to get up and visit the bathroom at night, not being able to see properly and bumping into obstacles, and having to use walking aids for pre-existing physical issues.

Improving sleep in the elderly

Due to the abovementioned issues it would seem prudent to promote an adequate amount of sleep, especially in the elderly who are more prone to developing issues such as dementia and who already have an increased risk of mortality.

A study has shown that supplementing with melatonin, a hormone produced by the pineal gland in the brain and which regulates the sleep-wake cycle, helps to promote an adequate amount of sleep in affected individuals.9

Elderly patients who are prone to sleep disorders have been noted to be those who are on chronic medications. These medications can disrupt the production and clearance of melatonin by the body, thus resulting in the sleep-related issues experienced by the affected individual.


The recommendation made by the researchers, in the clinical studies used for this article, is that an adequate amount of sleep of between six to eight hours is achieved by elderly people. Less than 5 hours and more than 9 hours of sleep can have detrimental effects on the physical and psychological well-being of these individuals.


  1. Scullin, M. K. (2013). Sleep, memory, and aging: the link between slow-wave sleep and episodic memory changes from younger to older adults.Psychology and aging,28(1), 105.
  2. Drummond, S. P., & Brown, G. G. (2001). The effects of total sleep deprivation on cerebral responses to cognitive performance.Neuropsychopharmacology, 25, S68-S73.

3. Ferman, T.J., Smith, G.E., Dickson, D.W., Graff-Radford, N.R, Lin, S-C., Wszolek, Z., … & Boeve, B.F. (2014). Abnormal daytime sleepiness in dementia with Lewy bodies compared to Alzheimer’s disease using the Multiple Sleep Latency Test. Alzheimer’s Research & Therapy, 6, 76.

  1. Iranzo, A., Molinuevo, J. L., Santamaría, J., Serradell, M., Martí, M. J., Valldeoriola, F., & Tolosa, E. (2006). Rapid-eye-movement sleep behaviour disorder as an early marker for a neurodegenerative disorder: a descriptive study.The Lancet Neurology,5(7), 572-577.
  2. Hall, M. H., Smagula, S. F., Boudreau, R. M., Ayonayon, H. N., Goldman, S. E., Harris, T. B., … & Stone, K. L. (2015). Association between sleep duration and mortality is mediated by markers of inflammation and health in older adults: the health, aging and body composition study.Sleep,38(2), 189-195.
  3. Livingston, G., Blizard, B., & Mann, A. (1993). Does sleep disturbance predict depression in elderly people? A study in inner London.Br J Gen Pract,43(376), 445-448.
  4. Hill, E. L., Cumming, R. G., Lewis, R., Carrington, S., & Couteur, D. G. L. (2007). Sleep disturbances and falls in older people.The Journals of Gerontology Series A: Biological Sciences and Medical Sciences,62(1), 62-66.
  5. Hill, E. L., Cumming, R. G., Lewis, R., Carrington, S., & Couteur, D. G. L. (2007). Sleep disturbances and falls in older people.The Journals of Gerontology Series A: Biological Sciences and Medical Sciences,62(1), 62-66.
  6. Garfinkel, D., Laudon, M., Nof, D., & Zisapel, N. (1995). Improvement of sleep quality in elderly people by controlled-release melatonin.The Lancet,346(8974), 541-544.