First explored in 1940s clinical literature, sundowning syndrome is a phenomenon characterised by the emergence or intensification of psychiatric symptoms in the late afternoon to early evening.
Also known as sundowning or nocturnal delirium, this condition causes confusion, psychomotor agitation, aggression, and hallucinations that continue into the night. Although these symptoms typically improve or disappear during the day, they remain mentally, emotionally, and physically taxing and pose great challenges to caregivers, healthcare staff, and families.
Sundowning syndrome predominantly affects older individuals experiencing cognitive decline and has been observed most closely within inpatient elderly facilities and hospitals. Studies show that up to 66% of patients with dementia experience sundowning, and specifically those with Alzheimer’s are at risk of developing the syndrome in the mid to late stages of the disease.
Although most healthcare staff, including physicians and nurses, consider sundowning a well-documented syndrome, dissenters in the medical field cite a lack of comprehensive studies verifying it as more than an early stage of dementia.
More clinical study using consistent measurement tools is still needed. However, sundowning has already been explored through the lens of several biopsychosocial factors.
Physical causes
Sundowning syndrome has many possible physical origins, which can each contribute to varying degrees. For example, taking antipsychotics, anticholinergics, antidepressants, and hypnotics can cause similar side effects of agitation and disrupted behaviour once taken or as they wear off.
Issues of fatigue, hunger, and other unmet needs can cause symptoms due to triggering changes in body temperature, glucose levels, and blood pressure.
Medical concerns, including pain from other illnesses, can intensify difficulties. Environmental deficits such as inadequate light exposure and overstimulation due to chaotic surroundings may also be involved.
The impact of caregiver dynamics also cannot be understated, as caregiver fatigue can decrease much-needed emotional and practical support levels. Issues in inpatient elderly facilities of low patient-to-staff ratios and abrupt changes in employee work shifts are also known to impact patients’ well-being negatively.
Indeed, the experience of institutionalisation is itself tied to poorer health levels in the elderly.
Neurological causes
Several possible neurological causes of sundowning require further study. For example, the body’s natural decrease in melatonin production as one age disrupts nighttime routines.
Levels of the hormone melatonin are meant to help regulate the nervous system, and abnormal deficiency has been linked to various issues, including mood disorders, severe pain, and different forms of dementia.
Another neurogenetic concern is the influence of the APOEɛ4 allele, an alternative form of the APOE gene that causes steeper cognitive decline in old age and increases the risk of developing Alzheimer’s three to fourfold.
Roughly 25% of people carry at least one copy of the APOEɛ4 gene; however, inheriting the gene does not necessarily lead to the onset of Alzheimer’s.
A third contributing factor could be rapid eye movement sleep behaviour disorder (RBD), a parasomnia where sufferers act out their dreams through movements or vocalisations.
Causes of RBD can include neurodegenerative disease, the use of antidepressants, and the presence of secondary medical conditions such as narcolepsy. RBD is disturbing for sufferers and caregivers and can lead to serious injury.
Fourthly, dysfunction of the neurotransmitter acetylcholine is known to contribute to cognitive deficits. Acetylcholine is the parasympathetic nervous system’s primary neurotransmitter, which helps lower heart rate and blood pressure to reach a ‘rest and digest state.
Researchers have proposed that cholinergic deficiency contributes to the development of schizophrenia symptoms, including visual hallucinations.
Damaged circadian rhythms
Sleep issues informing sundowning syndrome have been studied the most extensively. As the name suggests, the influence of changes in sunlight is involved, as is the circadian rhythm.
Our circadian rhythm governs sleep and bodily responses to light changes following an approximately 24-hour cycle. The ‘master circadian pacemaker’ is the hypothalamus’s suprachiasmatic nucleus (SCN).
The hypothalamus is a small brain structure that plays a crucial role in regulating the autonomic nervous system, releasing hormones, and managing essential bodily needs like hunger. Degeneration of the SCN from ageing and illnesses has been found in patients with circadian rhythm disorders.
As one age, the accumulation of plaque around the SCN leads to an impaired circadian rhythm. Alzheimer’s disease is also associated with later acrophase, or peak body core temperature, which disrupts the SCN’s ability to synchronize internal rhythms with environmental cues like the sunset.
Additionally, increased aggression related to sundowning may be linked to neuropathological abnormalities like damaged hypothalamic pathways meant to regulate behaviour. As part of a vicious cycle, symptoms exacerbate each other and worsen as the night goes on, making it even more difficult to fall asleep.
Treatment Options
Thus far, available treatments range from traditional pharmacotherapies and creative arts therapies to experimental homoeopathic remedies. There is no clear evidence of further medications preventing the condition for those already taking medications.
Healthcare staff are generally instructed to limit medication to the most severe, non-responsive cases of sundowning.
Alternative therapies that have proven helpful in decreasing symptoms include music therapy, light therapy, aromatherapy, multisensory stimulation therapy, and simulated presence therapy.
Music therapy has been found to improve cognitive function for those with dementia, and some view aromatherapy as an appropriate adjunct treatment for pain. Meta-analyses have shown that light therapy, including white and blue light, effectively treats non-seasonal geriatric depression.
Multisensory stimulation therapy uses controlled stimulation of the primary senses, including touch and sight, with excitatory stimuli for patients with more depressive symptoms and relaxing stimuli for those with more anxious or aggressive behaviour.
Simulated presence therapy is an emotion-oriented treatment used in nursing homes where personalised video or audio recordings from loved ones are played for the elderly to encourage relaxation.
Finally, no efforts are complete without caregiver education, adherence to daily routines, physical exercise, and sleep hygiene. Indeed, older adults and the elderly require the same amount of sleep as other adults each night, approximately seven–nine hours.
Utilising the diverse range of treatment options can support better mood, cognition, and overall health, essential for those already experiencing cognitive decline.
Marian Ting is an associate marriage and family therapist who is passionate about articulating phenomena, theories, and research related to the social sciences.
