Health Focus: What is Sundowning Syndrome?

Sundowning syndrome or nocturnal delirium is used to describe a wide range of behaviours of neuropsychiatric (NPS) symptoms that often happen in people with dementia. The behavioural and neuropsychiatric symptoms seen in people with dementia and Alzheimer’s disease include; repetitive behaviours, delusions, misidentification, wandering, suicidal and sociopathic behaviours. Both normal ageing and dementia are associated with changes to the circadian regulation of physiology and behaviour (Cipriani et al., 2015)

Sundowning syndrome or nocturnal delirium is used to describe a wide range of behaviours of neuropsychiatric (NPS) symptoms that often happen in people with dementia. The behavioural and neuropsychiatric symptoms seen in people with dementia and Alzheimer’s disease include; repetitive behaviours, delusions, misidentification, wandering, suicidal and sociopathic behaviours. Both normal ageing and dementia are associated with changes to the circadian regulation of physiology and behaviour (Cipriani et al., 2015).  Sundowning syndrome is not a disease but rather a set of symptoms that happen at specific times of the day usually around 16:00 – 17:00.  It can happen at any stage of dementia, but research shows it tends to peak during the middle stages of dementia. Sundowning shares the same similarities as delirium, e.g. attention deficits and activity disturbances.  

     A major difference between sundowning and delirium is that delirium tends be acute in onset and fluctuates during the day. Diagnosis of sundowning behaviours is purely clinical, and characterised by a wide range of cognitive, affective and behavioural issues. The impact of sundowning syndrome are huge, both in terms of the financial burden that are placed on the individual care of patients with dementia, and the emotional distress to the families. According to studies, sundowning symptoms are the main reasons families decide to move individuals with dementia to long-term care homes. The actual cause of sundowning syndrome is unknown, there are however several theories that attempt to explain this phenomenon. The literature that has attempted to explain sundowning can be grouped into three major themes, physiological, psychological and environmental (Khachiyants et al., 2011).

One of the most accepted pathophysiological mechanism underlying sundowning behaviours is centered around the dysfunction of the circadian rhythm. This is supported by the detection of pathological changes in the suprachiasmatic nucleus in people with Alzheimer’s. The suprachiasmatic nucleus is a small region of the brain in the hypothalamus, situated above the optic chiasm, it is known to be responsible for regulating the circadian rhythm (Ma & Morrison, 2020). The regulation of sleep is regulated by the haemostatic physiology of the circadian rhythm. The circadian rhythm is a 24-hour clock in the brain that regulates the sleep cycle. It regulates the cycles of alertness    and sleepiness by responding to light changes in the environment. Studies show that the body and behaviours is shaped by the earth’s rotation and axis. Without this in-built clock, individuals would not be able to optimise energy expenditure of the internal physiology of the body (Reddy et al., 2020).  The pineal gland is a central structure in the circadian system responsible for the production of melatonin under the control of the central clock. Melatonin production is controlled by the circadian timing system and is also suppressed by light. Light and dark changes constitute the principle timing signal of melatonin secretion from the pineal gland. The circadian clock is synchronised to the 24-hour day environmental light, which is transmitted from the retina to the SCN primarily through the retinohypothamlamic tract (Wu & Swaab, 2005). 

      The disruption of circadian system in dementia can in theory explain sleep disorders, agitation, confusion and other symptoms of dementia and may also contribute to the development of sundowning syndrome (Cipriani et al., 2015). Ageing and dementia can lead to the reduction in the consolidation of NREM sleep, decreased sleep efficiency, increased sleep disturbances and elevated levels of daytime napping. These sleep disturbances are common in ageing and are made worse by the presence of dementia. Over 38% of the elderly report having difficulties with sleep.  Studies show that people with dementia that have sleep disturbances also suffer from severe forms of dementia (Montag et al., 2015).  (Shenker & Singh, 2017), found that sleep disorders and neurocognitive disorders are both frequent categories of diseases, but they are often underdiagnosed. The relationship between sleep and neurocognition is complicated. In some cases, it is hard to work out whether the neurocognition disorders is causing the sleep disturbance or the sleep disturbance is causing the neurocognitive disorder.

Furthermore, sensory deprivation has been reported widely in the elderly and is generally associated with poor quality of life in all domains of the activities of daily living, such as eating and personal hygiene. People with dementia are more likely to spend time in doors with deem lights and are more likely to be isolated, which affects their sleep to wake patterns. More broadly sensory deprivation has been linked to the development of psychiatric disorders such as depression, anxiety, psychosis, dementia and sensory confusion. In the elderly, sensory depravation has been linked to rapid cognitive decline (Sahoo, 2016). Environmental factors that are said to contribute to sundowning occurrence, include; exposure to inadequate amounts of light, environmental overstimulation and low staff patient ratios in nursing homes. Other studies indicate that behavioural issues in people with dementia can be attributed to unmet needs.  But meeting the individualised care needs of every resident under a nurse’s care becomes harder without adequate staffing. Other studies have suggested that low lighting and increased shadows may increase late day confusion observed in  sundowning syndrome (Khachiyants et al., 2011).

Finally, sundowning behaviours can also be a side effect of a combination of medication and in some cases the wearing off of pharmaceuticals meant to manage dementia symptoms (Smalbrugge et al., 2017). Several medications may induce restlessness, akathisia or more serious movement disorders by causing extrapyramidal symptoms. For example, common side effects of Risperdal include; sudden often jerky involuntary motions of the head and arms. Other side effects include; dizziness, tiredness, fatigue and drowsiness. It is well known in literature that any pharmacological agents and a combination of different medications may induce cognitive, affective and behavioural changes in individuals with dementia (Janus et al., 2016). And to add to the complexity, the medications that are meant to manage the condition can also sometimes worsen the behavioural symptoms. Hypnotics, benzodiazepines and low potency antipsychotics are among the most widely used medication to manage behavioural issues related to sundowning. Side effects of such medicationsp include; akathisia, tardive dyskinesia and muscle rigidity.  Widely used benzodiazepines and other hypnotics to control agitation in elderly people with other comorbidities have been shown to create drug dependence, tolerance, and central and respiratory system depression.  Benzodiazepines have also been shown to cause paradoxical agitation and confusion in elderly individuals with pre-existing agitation who have sundowning syndrome (Nørgaard et al., 2017).  

Management of sundowning behaviours in dementia requires a multidisciplinary approach, and in these cases, there is no one size fit all approach. Management of behavioural symptoms requires a combination of pharmacological and non-pharmacological interventions. Nonpharmacological intervention should always be considered as first line and only use pharmacological agents as last resort. Tips for managing sundowning syndrome non pharmacologically include; limiting daytime napping and planning for daytime activities. Also, exposure to light during the day to encourage night-time sleep, maintaining a predictable routine for bedtime, waking and mealtimes. In the evening it is important to reduce background noise and other stimulating activities, including TV viewing. Other studies indicate that the use of melatonin, a natural hormone that helps with sleep may aid in the management of sleep disturbances in dementia. when medications to manage dementia symptoms are prescribed, it is essential to review their efficacy regularly.


Cipriani, G., Lucetti, C., Carlesi, C., Danti, S., & Nuti, A. (2015). Sundown syndrome and dementia. European Geriatric Medicine, 6(4), 375–380. https://doi.org/10.1016/j.eurger.2015.03.006

Janus, S. I. M., Manen, J. G. van, IJzerman, M. J., & Zuidema, S. U. (2016). Psychotropic drug prescriptions in Western European nursing homes. International Psychogeriatrics, 28(11), 1775–1790. https://doi.org/10.1017/S1041610216001150

Khachiyants, N., Trinkle, D., Son, S. J., & Kim, K. Y. (2011). Sundown Syndrome in Persons with Dementia: An Update. Psychiatry Investigation, 8(4), 275–287. https://doi.org/10.4306/pi.2011.8.4.275

Ma, M. A., & Morrison, E. H. (2020). Neuroanatomy, Nucleus Suprachiasmatic. In StatPearls. StatPearls Publishing. http://www.ncbi.nlm.nih.gov/books/NBK546664/

Montag, C., Kannen, C., Lachmann, B., Sariyska, R., Duke, É., Reuter, M., & Markowetz, A. (2015). The importance of analogue zeitgebers to reduce digital addictive tendencies in the 21st century. Addictive Behaviors Reports, 2, 23–27. https://doi.org/10.1016/j.abrep.2015.04.002

Nørgaard, A., Jensen-Dahm, C., Gasse, C., Hansen, E. S., & Waldemar, G. (2017). Psychotropic Polypharmacy in Patients with Dementia: Prevalence and Predictors. Journal of Alzheimer’s Disease, 56(2), 707–716. https://doi.org/10.3233/JAD-160828

Reddy, S., Reddy, V., & Sharma, S. (2020). Physiology, Circadian Rhythm. In StatPearls. StatPearls Publishing. http://www.ncbi.nlm.nih.gov/books/NBK519507/

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Shenker, J. I., & Singh, G. (2017). Sleep and Dementia. Missouri Medicine, 114(4), 311–315.

Smalbrugge, M., Zwijsen, S. A., Koopmans, R. C. T. M., & Gerritsen, D. L. (2017). Challenging Behavior in Nursing Home Residents with Dementia. In S. Schüssler & C. Lohrmann (Eds.), Dementia in Nursing Homes (pp. 55–66). Springer International Publishing. https://doi.org/10.1007/978-3-319-49832-4_5

Wu, Y.-H., & Swaab, D. F. (2005). The human pineal gland and melatonin in aging and Alzheimer’s disease. Journal of Pineal Research, 38(3), 145–152. https://doi.org/10.1111/j.1600-079X.2004.00196.x