Overview 

Lewy Body Dementia (LBD) is a complex neurodegenerative disease characterized by psychological and motor symptoms, cognitive impairment, and sleep disturbances.¹ One of the critical functions of sleep is its impact on the central nervous system, memory, behavioral regulation, and overall cerebral activity. Inadequate sleep significantly exacerbates cognitive impairment, affects emotional stability, and diminishes daily life quality. Resolving sleep problems in LBD patients is essential for alleviating symptoms and enhancing well-being, as sufficient sleep is necessary to bolster cognitive and emotional coping abilities required to manage the challenges of this complex disease.

Types of Sleep Disturbances in LBD

Sleep disturbances are some of the most common yet debilitating symptoms of Lewy Body Dementia, exacerbating disease progression and significantly impacting cognitive and psychological health. They manifest in various forms in patients with LBD: 

REM Sleep Behaviour Disorder: acting out dreams in REM sleep

During normal REM sleep, temporary paralysis (muscle atonia) prevents individuals from physically acting out their dreams. However, REM sleep behaviour disorder results in the loss of such atonia, often causing individuals to violently act out their dreams through behaviours like kicking, vocalizing or thrashing.²

In Lewy Body Dementia, one of the earliest indicators of neurodegeneration is RBD, indicating declining cognition. The region responsible for RBD, the brainstem, is involved in REM atonia – areas such as subcoeruleus and pontine areas affected early in the degeneration process. With the gradual progression of degeneration, areas such as the cerebellar cortex and substantia nigra are affected, leading to parkinsonism and visual hallucinations. The connection between RBD and LBD is supported by the presence of Lewy bodies in the brainstem, with pathology correlating to loss of REM atonia.

A study highlighted up to 74% of LBD patients showing RBD symptoms, further highlighting the role of sleep disturbances as a biomarker for neurodegeneration, and providing further insights into the role of synucleinopathies like Lewy bodies developing. 

Excessive Daytime Sleepiness

LBD patients also experience excessive daytime sleepiness, attributed to several pathological and anatomical factors. Firstly, the presence of Lewy bodies disrupts the functioning of critical brain regions involved in circadian sleep-wake cycles such as the brainstem and hypothalamus. These lead to fragmented sleep and increased daytime drowsiness. LBD also results in obstructive sleep apnea, comorbid depression, and medication side effects, contributing to a shift in circadian rhythms.

In one study,⁴ patients with LBD were found to exhibit significantly higher levels of EDS compared to other types of dementias, indicating its role as a potential distinguishing factor from other dementias.

Another study⁵ reinforced these findings by identifying slow-wave patterns associated with sleep fragmentation and its contribution to physical and cognitive restoration, leading to emotional episodes.

Pathologies and disruptions in such neural processes responsible for sleep-wake regulation, the presence of sleep disorders like RBD, and the effects of medications all contribute to the complexity of EDS in these conditions. Understanding these mechanisms is crucial for developing targeted interventions to manage EDS and improve the quality of life for patients suffering from these challenging disorders.

Periodic Limb Movement Disorder - uncontrolled limb movements during sleep 

Restless Leg Syndrome (RLS), characterized by the uncontrollable urge to move legs, has been revealed to have overlaps in manifestation in LBD disorders, which significantly complicates management.

RLS is marked by 4 critical features: the urge to move legs, unpleasant sensations in legs, worsening of symptoms during inactivity, and a sense of relief experienced through movement. Commonly, RLS peaks during the evening. In patients with LBD, RLS may also manifest as wandering behaviours – a well-documented challenge in dementia care, representing a significant safety concern for patients.⁶

In patients with LBD, the presence of RLS can manifest as excessive motor activity, leg discomfort, and even wandering behaviours. Wandering is a well-documented challenge in dementia care, representing a significant safety concern for patients. Some researchers suggest that wandering behaviours are indicative of RLS, however, its precise neural underpinnings are yet to be fully discovered. Some studies hypothesize the role of dopamine disruptions responsible for regulating sensory and motor experiences, whereas neuroimaging studies highlighted the key regions for such reduced dopamine intake associated with motor control in RLS and LBD. However, further research and interventions are necessary to fully understand disease aetiology and management of symptoms. 

Obstructive Sleep Apnea 

Obstructive Sleep Apnoea (OSA) is characterised by partial or complete airway collapse during sleep, leading to poor sleep, excessive daytime sleepiness, and depression. While factors such as age, BMI, and sex affect LBD, additional risks from LBD such as weakened airway muscles and sedating medications reveal links between neuropathology and LBD.⁷

In neurodegeneration such as LBD, processes affecting motor control also affect upper airway muscles. These muscles are tonically active during sleep to keep the airway open. However, in LBD, degeneration of motor neurons leads to a reduction in muscle tone, resulting in airway collapse and obstructive events. Moreover, the medullary raphe nuclei, which is responsible for regulating respiration, leads to abnormal breathing patterns during sleep. Studies have shown that DLB patients exhibit a decreased ventilatory response to hypercapnia (elevated CO2 levels), indicating a failure of respiratory compensation, especially during sleep when respiratory control is more dependent on autonomic regulation. This dysfunction increases the likelihood of sleep-disordered breathing and contributes to OSA pathology in LBD.

Impact of Sleep Disturbance on Disease Progression 

Cognitive Decline 

The cognitive profile of LBD differs from other types of dementia in presenting unique cognitive challenges – in attention, executive function, and visuospatial skills. Commonly, one of the hallmark features of LBD is fluctuation in attention and alertness – where patients show near-normal cognitive function, followed by episodes of drowsiness or inattentiveness. As these changes occur quickly and are unpredictable, this variability makes LBD more difficult to manage. Some of the predominant causes are disruptions in neurotransmitter systems – particularly the cholinergic system playing a key role in attention deficits.⁸ Another set of cognitive processes that deteriorate are the executive functions, which represent the early signs of the disease. Patients struggle with tasks that require organizing thoughts, switching between tasks, or following instructions, predominantly due to damage in frontal regions. Patients with LBD also witness visual hallucinations, involving persecution or misidentification. Further, cognitive symptoms are exacerbated by disturbances in sleep architecture – due to REM sleep behaviour disorder and insomnia. Furthermore, the effects of hypoxia from neurovascular damage are caused by Obstructive sleep apnoea, affecting cognitive and neurological health.⁹

Emotional and behavioural symptoms 

In LBD, emotional disturbances such as depression, anxiety, and mood swings are linked to problems in sleep. Disrupted sleep from RBD and insomnia commonly cause irritability and emotional instability. Moreover, evidence links the rising levels of depression to excessive daytime sleepiness, causing chronic fatigue and reduced emotional resilience. Patients are thus prone to experiencing hyper or hypoemotional reactivity, reduced coping skills, and a decline in emotional well-being.¹⁰

Treatment and management of sleep disturbance in LBD

Managing sleep disturbances in LBD includes both pharmacological and non-pharmacological interventions to effectively improve overall medical outcomes (neurological, cognitive, and emotional). 

Pharmacological Interventions

Some pharmacological interventions include clonazepam for RBD, helping reduce nighttime symptoms. However, attention to dosage is essential to prevent unprecedented side effects such as daytime drowsiness and gait issues. Melatonin is also frequently prescribed to improve sleep quality. CPAP therapy (Continuous Positive Airway Pressure) is a commonly used treatment for OSA, where a machine provides a steady stream of air through the mask to keep the airway open.¹¹

Non-pharmacological interventions 

These include a few behavioural improvements, like sleep hygiene – establishing a consistent sleep routine, avoiding caffeine and alcohol during specific times of the day, and limiting naps to improve sleep quality. Moreover, interventions such as light therapy utilize bluish-white lights during the day, increase total sleep time, and reduce agitation, thereby reducing cognitive fluctuations.¹² Creating an optimal sleep environment is extremely useful to prevent injuries and mitigate nighttime risks, especially to prevent accidents from RLS. Lifestyle interventions such as weight management, limiting sedative intake, and encouraging physical activity help create restful nights. 

Summary

Sleep disturbances are critical in Lewy Body Dementia, acting as both contributors and symptoms of disease progression.

Common sleep disturbances such as REM Sleep Behaviour Disorder, Insomnia, and Excessive daytime sleepiness not only disrupt rest, but also exacerbate cognitive decline, hallucinations, and worsen the physical symptoms of LBD.

These disturbances therefore impact daily functioning and quality of life for both parents as well as caregivers, who undergo excessive stress and fatigue due to additional nighttime care and support.

Addressing such issues through pharmacological and non-pharmacological solutions such as medications, behavioural, physical and light therapy, and lifestyle adjustments to improve sleep hygiene help stabilize symptoms, slow cognitive deterioration and improve adjustments to everyday life.

More research must be done to undercover the complex interplay of sleep and neurodegeneration processes, and efforts must be undertaken to educate patients and caregivers on the integration of sleep care into LBD treatment.