Treatment of sleep disturbance in Alzheimer's disease

Walking Interventions and Sleep Quality of Persons Living With Dementia and Their Family Caregivers: Effects of Different Walking Companions

PURPOSE

To examine the effect of walking interventions on sleep quality of persons with dementia (PWD) and their caregivers (dyads), and how different companions affect results.

METHOD

Forty-five dyads were divided into three groups: a control group and two experimental groups (one with a care attendant, one with a family caregiver). The two experimental groups engaged in 120 minutes of walking per week for 24 weeks.

RESULTS

A significant improvement in sleep quality was observed among PWD in the family caregiver group (Wald χ2 = 4.55, p = 0.033), whereas there was no improvement in the care attendant group. A slight improvement in sleep quality of family caregivers was also found.

CONCLUSION

Findings suggest the importance of creating individualized walking activity plans for dyads, incorporating trust and rapport-building strategies to improve sleep quality. [Journal of Gerontological Nursing, 50(8), 46-56.].

Applicability of the Self-Evaluation Scale of nursing practices for improving sleep quality among patients with dementia taking sleeping pills to general nurses

Objective

Many patients with dementia experience sleep-related problems. However, there is a lack of clarity regarding nursing practices that can address these issues. Thus, we developed a self-assessment scale for nursing practices to improve sleep quality among patients with dementia taking sleep medication and confirmed its validity and reliability. This study aimed to test the validity and reliability of this scale for adaptability to general nurses and test its applicability.

Participants and Methods

The survey included basic attributes and questionnaire items related to nursing practices to improve sleep quality in patients with dementia taking sleeping pills. Data from 477 participants with no missing values in the survey items were used in the analysis. The self-evaluation scale of nursing practices for improving sleep quality among patients with dementia taking sleeping pills was based on a three-factor model, and confirmatory factor analysis was performed using structural equation modeling.

Results

Goodness-of-fit indices were satisfactory, supporting the construct validity of the scale. Cronbach's α coefficients for the total score and the three factors of the self-evaluation scale of nursing practices for improving sleep quality among patients with dementia taking sleeping pills exceeded 0.7.

Conclusion

The development of this scale can improve the quality of nursing practice for patients with dementia who take sleeping pills. Moreover, it can serve as evidence for general nurses to participate in drug treatment and can be considered as basic research for appropriate drug treatment in nursing practice.

Clinical usefulness of dual orexin receptor antagonism beyond insomnia: Neurological and psychiatric comorbidities

Orexin is a neurotransmitter produced by a small group of hypothalamic neurons. Besides its well-known role in the regulation of the sleep-wake cycle, the orexin system was shown to be relevant in several physiological functions including cognition, mood and emotion modulation, and energy homeostasis. Indeed, the implication of orexin neurotransmission in neurological and psychiatric diseases has been hypothesized via a direct effect exerted by the projections of orexin neurons to several brain areas, and via an indirect effect through orexin-mediated modulation of sleep and wake. Along with the growing evidence concerning the use of dual orexin receptor antagonists (DORAs) in the treatment of insomnia, studies assessing their efficacy in insomnia comorbid with psychiatric and neurological diseases have been set in order to investigate the potential impact of DORAs on both sleep-related symptoms and disease-specific manifestations. This narrative review aimed at summarizing the current evidence on the use of DORAs in neurological and psychiatric conditions comorbid with insomnia, also discussing the possible implication of modulating the orexin system for improving the burden of symptoms and the pathological mechanisms of these disorders. Target searches were performed on PubMed/MEDLINE and Scopus databases and ongoing studies registered on Clinicaltrials.gov were reviewed. Despite some contradictory findings, preclinical studies seemingly support the possible beneficial role of orexin antagonism in the management of the most common neurological and psychiatric diseases with sleep-related comorbidities. However, clinical research is still limited and further studies are needed for corroborating these promising preliminary results.

Comparative efficacy of various exercise interventions on sleep in patients with cognitive impairment: a systematic review and meta-analysis

Background

Sleep disturbances are an early indicator of cognitive impairment and exacerbate its progression. While pharmacological treatments for sleep disorders exist, their side-effect profile includes an increased risk of falls and the potential to exacerbate cognitive impairment. Non-pharmacological treatments such as physical exercise should be considered. However, uncertainties persist. We aimed to assess the potential benefits of exercise interventions on sleep in patients with cognitive impairment and determine the specific effects of various exercise modalities.

Materials and methods

A systematic search was performed on seven databases for eligible studies published before Nov 2022. Randomized controlled trials of exercise for patients with cognitive impairment (mild cognitive impairment and Alzheimer's disease) were included. All analyses were conducted using RevMan version 5.4. Meta-analysis and The Grading of Recommendations Assessment Development and Evaluations (GRADE) quality ratings were performed on sleep quality and objective sleep data.

Results

A total of 8 randomized controlled trials were included with a sample size of 486 subjects. For patients with cognitive impairment, physical exercise had a beneficial effect on sleep quality [MD = -3.55 (-5.57, -1.32), Z = 3.13, p = 0.002] and total sleep time [MD = 33.77 (23.92, 43.62), Z = 6.72, P < 0.00001]. No improvement was found in sleep efficiency and nocturnal awakening time. Subgroup analysis showed that multi-component exercise produced superior results.

Conclusion

Physical exercise may improve sleep quality and total sleep time for patients with cognitive impairment. Multi-component exercise designed individually is more effective. Large-scale randomized controlled trials with objective sleep outcome measurements are warranted.Clinical trial registration: https://www.crd.york.ac.uk/prospero/, identifier: CRD42022377221.

Sleep Biomarkers for Predicting Cognitive Decline and Alzheimer's Disease: A Systematic Review of Longitudinal Studies

BACKGROUND

Sleep disturbances are considered a hallmark of dementia, and strong evidence supports the association between alterations in sleep parameters and cognitive decline in patients with mild cognitive impairment and Alzheimer's disease (AD).

OBJECTIVE

This systematic review aims to summarize the existing evidence on the longitudinal association between sleep parameters and cognitive decline, with the goal of identifying potential sleep biomarkers of AD-related neurodegeneration.

METHODS

Literature search was conducted in PubMed, Web of Science, and Scopus databases from inception to 28 March 2023. Longitudinal studies investigating the association between baseline objectively-measured sleep parameters and cognitive decline were assessed for eligibility.

RESULTS

Seventeen studies were included in the qualitative synthesis. Sleep fragmentation, reduced sleep efficiency, reduced REM sleep, increased light sleep, and sleep-disordered breathing were identified as predictors of cognitive decline. Sleep duration exhibited a U-shaped relation with subsequent neurodegeneration. Additionally, several sleep microstructural parameters were associated with cognitive decline, although inconsistencies were observed across studies.

CONCLUSIONS

These findings suggest that sleep alterations hold promise as early biomarker of cognitive decline, but the current evidence is limited due to substantial methodological heterogeneity among studies. Further research is necessary to identify the most reliable sleep parameters for predicting cognitive impairment and AD, and to investigate interventions targeting sleep that can assist clinicians in the early recognition and treatment of cognitive decline. Standardized procedures for longitudinal studies evaluating sleep and cognition should be developed and the use of continuous sleep monitoring techniques, such as actigraphy or EEG headband, might be encouraged.

How to Prevent and/or Revert Alzheimer's Disease Continuum During Preclinical Phases

The development of Alzheimer's disease (AD) follows three consecutive phases: namely preclinical, prodromal or mild cognitive impairment (MCI), and dementia. In addition, the preclinical phase can be divided into subphases related to the presence of biomarkers that appear at different points before the onset of MCI. Indeed, an early risk factor could promote the appearance of additional ones through a continuum. The presence of various risk factors may trigger specific biomarkers. In this review, we comment on how modifiable risk factors for AD may be reverted, thus correlating with a possible decrease in the specific biomarkers for the disease. Finally, we discuss the development of a suitable AD prevention strategy by targeting modifiable risk factors, thereby increasing the level of "precision medicine" in healthcare systems worldwide.

Sleep quality differentially modulates neural oscillations and proteinopathy in Alzheimer's disease

BACKGROUND

Alterations in resting-state neural activity have been reported in people with sleep disruptions and in patients with Alzheimer's disease, but the direct impact of sleep quality on Alzheimer's disease-related neurophysiological aberrations is unclear.

METHODS

We collected cross-sectional resting-state magnetoencephalography and extensive neuropsychological and clinical data from 38 biomarker-confirmed patients on the Alzheimer's disease spectrum and 20 cognitively normal older control participants. Sleep efficiency was quantified using the Pittsburgh Sleep Quality Index.

FINDINGS

Neural activity in the delta frequency range was differentially affected by poor sleep in patients on the Alzheimer's disease spectrum. Such neural changes were related to processing speed abilities and regional amyloid accumulation, and these associations were mediated and moderated, respectively, by sleep quality.

INTERPRETATION

Together, our results point to a mechanistic role for sleep disturbances in the widely reported neurophysiological aberrations seen in patients on the Alzheimer's disease spectrum, with implications for basic research and clinical intervention.

FUNDING

National Institutes of Health, USA.

Sleep fragmentation affects glymphatic system through the different expression of AQP4 in wild type and 5xFAD mouse models

Alzheimer's disease (AD) is characterized by genetic and multifactorial risk factors. Many studies correlate AD to sleep disorders. In this study, we performed and validated a mouse model of AD and sleep fragmentation, which properly mimics a real condition of intermittent awakening. We noticed that sleep fragmentation induces a general acceleration of AD progression in 5xFAD mice, while in wild type mice it affects cognitive behaviors in particular learning and memory. Both these events may be correlated to aquaporin-4 (AQP4) modulation, a crucial player of the glymphatic system activity. In particular, sleep fragmentation differentially affects aquaporin-4 channel (AQP4) expression according to the stage of the disease, with an up-regulation in younger animals, while such change cannot be detected in older ones. Moreover, in wild type mice sleep fragmentation affects cognitive behaviors, in particular learning and memory, by compromising the glymphatic system through the decrease of AQP4. Nevertheless, an in-depth study is needed to better understand the mechanism by which AQP4 is modulated and whether it could be considered a risk factor for the disease development in wild type mice. If our hypotheses are going to be confirmed, AQP4 modulation may represent the convergence point between AD and sleep disorder pathogenic mechanisms.

The Effects of Light Therapy on Sleep, Agitation and Depression in People With Dementia: A Systematic Review and Meta-analysis of Randomized Controlled Trials

OBJECTIVE

To evaluate the effects of light therapy on the alleviation of sleep disturbances, agitation and depression in people with dementia.

METHODS

A search was performed in PubMed, Medline, SCOPUS, Web of Science, EMBASE, CINAHL, Cochrane Library, for studies published between 2000 and 2021.

RESULTS

A total of 4315 articles were screened. Sixteen articles were eligible for this review and 11 randomized controlled studies were included in the meta-analysis. Light therapy had a significant effect on reducing the number of awakenings in sleep (n = 4; 95% CI = -.56, -.05; I2 = 0%; SMD = -.31) but was not significant in reducing the wake after sleep onset (n = 3; 95% CI = -.14, .59; I2 = 0%; SMD = .23), agitation (n = 4; 95% CI = -1.02, .45; I2 = 87%; SMD = -.28) and depression (n = 6; 95% CI = -.80, .40, I2 = 85%; SMD = -.20).

CONCLUSION

Light therapy appeared to be more effective in terms of alleviating sleep disturbances, rather than reducing agitation and depression, but its long-term effects remain unclear.

A Dichotomous Role for FABP7 in Sleep and Alzheimer's Disease Pathogenesis: A Hypothesis

Fatty acid binding proteins (FABPs) are a family of intracellular lipid chaperone proteins known to play critical roles in the regulation of fatty acid uptake and transport as well as gene expression. Brain-type fatty acid binding protein (FABP7) is enriched in astrocytes and has been implicated in sleep/wake regulation and neurodegenerative diseases; however, the precise mechanisms underlying the role of FABP7 in these biological processes remain unclear. FABP7 binds to both arachidonic acid (AA) and docosahexaenoic acid (DHA), resulting in discrete physiological responses. Here, we propose a dichotomous role for FABP7 in which ligand type determines the subcellular translocation of fatty acids, either promoting wakefulness aligned with Alzheimer's pathogenesis or promoting sleep with concomitant activation of anti-inflammatory pathways and neuroprotection. We hypothesize that FABP7-mediated translocation of AA to the endoplasmic reticulum of astrocytes increases astrogliosis, impedes glutamatergic uptake, and enhances wakefulness and inflammatory pathways via COX-2 dependent generation of pro-inflammatory prostaglandins. Conversely, we propose that FABP7-mediated translocation of DHA to the nucleus stabilizes astrocyte-neuron lactate shuttle dynamics, preserves glutamatergic uptake, and promotes sleep by activating anti-inflammatory pathways through the peroxisome proliferator-activated receptor-γ transcriptional cascade. Importantly, this model generates several testable hypotheses applicable to other neurodegenerative diseases, including amyotrophic lateral sclerosis and Parkinson's disease.

Sleep in Alzheimer's disease: a systematic review and meta-analysis of polysomnographic findings

Polysomnography (PSG) studies of sleep changes in Alzheimer's disease (AD) have reported but not fully established the relationship between sleep disturbances and AD. To better detail this relationship, we conducted a systematic review and meta-analysis of reported PSG differences between AD patients and healthy controls. An electronic literature search was conducted in EMBASE, MEDLINE, All EBM databases, CINAHL, and PsycINFO inception to Mar 2021. Twenty-eight studies were identified for systematic review, 24 of which were used for meta-analysis. Meta-analyses revealed significant reductions in total sleep time, sleep efficiency, and percentage of slow-wave sleep (SWS) and rapid eye movement (REM) sleep, and increases in sleep latency, wake time after sleep onset, number of awakenings, and REM latency in AD compared to controls. Importantly, both decreased SWS and REM were significantly associated with the severity of cognitive impairment in AD patients. Alterations in electroencephalogram (EEG) frequency components and sleep spindles were also observed in AD, although the supporting evidence for these changes was limited. Sleep in AD is compromised with increased measures of wake and decreased TST, SWS, and REM sleep relative to controls. AD-related reductions in SWS and REM sleep correlate with the degree of cognitive impairment. Alterations in sleep EEG frequency components such as sleep spindles may be possible biomarkers with relevance for diagnosing AD although their sensitivity and specificity remain to be clearly delineated. AD-related sleep changes are potential targets for early therapeutic intervention aimed at improving sleep and slowing cognitive decline.

The Effect of Bright Light Therapy on Sleep and Quality of Life in Patients With Poststroke Insomnia

OBJECTIVE

Poststroke insomnia is common and negatively affects stroke recovery. The objective of this study was to determine the effectiveness of bright light therapy for mild-to-moderate stroke patients with insomnia.

METHODS

This study was randomized, double blind, and placebo controlled. A 2-week trial was conducted on patients with mild-to-moderate stroke who had poststroke insomnia. Only patients who had experienced a first episode of stroke were enrolled in this study. Sleep parameters were measured using the Actiwatch Spectrum Pro for 7 days before and after light therapy. The instrument specifically collected data concerning sleep, mood state, fatigue, and subjective quality of life. Participants with poststroke insomnia received bright light therapy (10,000 lux) or placebo therapy for 30 minutes in the early morning. A total of 112 eligible participants entered the study, but only 56 patients were randomized to treatment (27 to bright light therapy and 29 to placebo therapy).

RESULTS

Results from analysis of variance showed that the mean change of sleep latency (F(1,55) =4.793, p = .033) and sleep efficiency (F(1,55) = 5.625, p = .022) were significantly superior in bright light therapy over placebo. Bright light therapy resulted in significant improvements in daytime sleepiness, fatigue, mood, and quality of life in study participants (p < .05).

CONCLUSIONS

Bright light therapy is a nonpharmacological treatment of early, poststroke insomnia in patients who had a mild to moderate stroke. In addition, bright light therapy is effective for the treatment of daytime sleepiness, fatigue, and depression and for improving quality of life in patients with poststroke insomnia.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04721574.

Connecting Mind-Body Therapy-Mediated Effects to Pathological Features of Alzheimer's Disease

Alzheimer's disease (AD) is a complex, multifactorial neurodegenerative disorder that represents a major and increasing global health challenge. In most cases, the first clinical symptoms of AD are preceded by neuropathological changes in the brain that develop years to decades before their onset. Therefore, research in the last years has focused on this preclinical stage of AD trying to discover intervention strategies that might, if implemented effectively, delay or prevent disease progression. Among those strategies, mind-body therapies such as yoga and meditation have gained increasing interest as complementary alternative interventions. Several studies have reported a positive impact of yoga and meditation on brain health in both healthy older adults and dementia patients. However, the underlying neurobiological mechanisms contributing to these effects are currently not known in detail. More specifically, it is not known whether yogic interventions, directly or indirectly, can modulate risk factors or pathological mechanisms involved in the development of dementia. In this article, we first review the literature on the effects of yogic practices on outcomes such as cognitive functioning and neuropsychiatric symptoms in patients with mild cognitive impairment and dementia. Then, we analyze how yogic interventions affect different risk factors as well as aspects of AD pathophysiology based on observations of studies in healthy individuals or subjects with other conditions than dementia. Finally, we integrate this evidence and propose possible mechanisms that might explain the positive effects of yogic interventions in cognitively impaired individuals.

Dementia Enlightened?! A Systematic Literature Review of the Influence of Indoor Environmental Light on the Health of Older Persons with Dementia in Long-Term Care Facilities

Light therapy for older persons with dementia is often administered with light boxes, even though indoor ambient light may more comfortably support the diverse lighting needs of this population. Our objective is to investigate the influence of indoor daylight and lighting on the health of older adults with dementia living in long-term care facilities. A systematic literature search was performed within PubMed, CINAHL, PsycINFO, Web of Science and Scopus databases. The included articles (n=37) were published from 1991 to 2020. These articles researched the influence of existing and changed indoor light conditions on health and resulted in seven categories of health outcomes. Although no conclusive evidence was found to support the ability of indoor light to decrease challenging behaviors or improve circadian rhythms, findings of two studies indicate that exposure to (very) cool light of moderate intensity diminished agitation. Promising effects of indoor light were to reduce depressive symptoms and facilitate spatial orientation. Furthermore, there were indications that indoor light improved one’s quality of life. Despite interventions with dynamic lighting having yielded little evidence of its efficacy, its potential has been insufficiently researched among this study population. This review provides a clear and comprehensive description of the impact of diverse indoor light conditions on the health of older adults with dementia living in long-term care facilities. Variation was seen in terms of research methods, (the description of) light conditions, and participants’ characteristics (types and severity of dementia), thus confounding the reliability of the findings. The authors recommend further research to corroborate the beneficial effects of indoor light on depression and to clarify its role in supporting everyday activities of this population. An implication for practice in long-term care facilities is raising the awareness of the increased lighting needs of aged residents.

The Sleep Side of Aging and Alzheimer's Disease

As we age, sleep patterns undergo significant modifications in micro and macrostructure, worsening cognition and quality of life. These are associated with remarkable brain changes, like deterioration in synaptic plasticity, gray and white matter, and significant modifications in hormone levels. Sleep alterations are also a core component of mild cognitive impairment (MCI) and Alzheimer's Disease (AD). AD night time is characterized by a gradual decrease in slow-wave activity and a substantial reduction of REM sleep. Sleep abnormalities can accelerate AD pathophysiology, promoting the accumulation of amyloid-β (Aβ) and phosphorylated tau. Thus, interventions that target sleep disturbances in elderly people and MCI patients have been suggested as a possible strategy to prevent or decelerate conversion to dementia. Although cognitive-behavioral therapy and pharmacological medications are still first-line treatments, despite being scarcely effective, new interventions have been proposed, such as sensory stimulation and Noninvasive Brain Stimulation (NiBS). The present review outlines the current state of the art of the relationship between sleep modifications in healthy aging and the neurobiological mechanisms underlying age-related changes. Furthermore, we provide a critical analysis showing how sleep abnormalities influence the prognosis of AD pathology by intensifying Aβ and tau protein accumulation. We discuss potential therapeutic strategies to target sleep disruptions and conclude that there is an urgent need for testing new therapeutic sleep interventions.

Disruption of metabolic, sleep, and sensorimotor functional outcomes in a female transgenic mouse model of Alzheimer's disease

Alzheimer's Disease (AD) is the most prevalent form of dementia globally, and the number of individuals with AD diagnosis is expected to double by 2050. Numerous preclinical AD studies have shown that AD neuropathology accompanies alteration in learning and memory. However, less attention has been given to alterations in metabolism, sleep, and sensorimotor functional outcomes during AD pathogenesis. The objective of this study was to elucidate the extent to which metabolic activity, sleep-wake cycle, and sensorimotor function is impaired in APPSwDI/Nos2^-/- (CVN-AD) transgenic mice. Female mice were used in this study because AD is more prevalent in women compared to men. We hypothesized that the presence of AD neuropathology in CVN-AD mice would accompany alterations in metabolic activity, sleep, and sensorimotor function. Our results showed that CVN-AD mice had significantly decreased energy expenditure compared to wild-type (WT) mice. An examination of associated functional outcome parameters showed that sleep activity was elevated during the awake (dark) cycle and as well as an overall decrease in spontaneous locomotor activity. An additional functional parameter, the nociceptive response to thermal stimuli, was also impaired in CVN-AD mice. Collectively, our results demonstrate CVN-AD mice exhibit alterations in functional parameters that resemble human-AD clinical progression.

Obstructive sleep apnea treatment disparities among older adults with neurological disorders

OBJECTIVE

The objective of the study was to characterize obstructive sleep apnea treatment patterns among older Americans with neurological conditions.

SETTING AND PARTICIPANTS

Claims data from a 5% fee-for-service sample of Medicare beneficiaries were analyzed to determine the proportion of older adults with OSA who received and were adherent to continuous positive airway pressure therapy and examine potential gaps in OSA care among neurological populations. Logistic regression was used to determine whether gender or race/ethnicity modified the associations between neurological morbidities and OSA treatment or adherence.

RESULTS

Data from n = 102,618 beneficiaries with OSA were identified. The prevalence of stroke, cognitive disorders, or Parkinson's disease in this sample was 7%, 3%, and 2% respectively. Overall, OSA-diagnosed individuals (73%) obtained treatment, and most treated were adherent to CPAP (72%). Lower proportions of OSA treatment and adherence were observed in neurological conditions, particularly stroke. In logistic regression models, gender and race/ethnicity each modified associations between neurological comorbidity and OSA treatment and adherence. Women as compared to men with a given neurological condition were uniformly less likely to receive CPAP or adhere to treatment (P < .01 for each condition). Similarly, in comparison to whites with the same neurological condition, OSA treatment was significantly lower among all other races with stroke, and among blacks with cognitive disorders.

CONCLUSIONS

Older women and minorities with neurological conditions may be more vulnerable to gaps in OSA care. Targeted strategies to improve treatment disparities and neurological outcomes in older adults could be informed by these data.

Screening of sleep assisting drug candidates with a Drosophila model

Lately, Drosophila has been favored as a model in sleep and circadian rhythm research due to its conserved mechanism and easily manageable operation. These studies have revealed the sophisticated parameters in whole-day sleep profiles of Drosophila, drawing connections between Drosophila sleep and human sleep. In this study, we tested several sleep deprivation protocols (mechanical shakes and light interruptions) on Drosophila and delineated their influences on Drosophila sleep. We applied a daytime light-deprivation protocol (DD) mimicking jet-lag to screen drugs that alleviate sleep deprivation. Characteristically, classical sleep-aid compounds exhibited different forms of influence: phenobarbital and pentobarbital modified total sleep time, while melatonin only shortened the latency to sleep. Such results construct the basis for further research on sleep benefits in other treatments in Drosophila. We screened seven herb extracts, and found very diverse results regarding their effect on sleep regulation. For instance, Panax notoginseng and Withania somnifera extracts displayed potent influence on total sleep time, while Melissa officinalis increased the number of sleep episodes. By comparing these treatments, we were able to rank drug potency in different aspects of sleep regulation. Notably, we also confirmed the presence of sleep difficulties in a Drosophila Alzheimer’s disease (AD) model with an overexpression of human Abeta, and recognized clear differences between the portfolios of drug screening effects in AD flies and in the control group. Overall, potential drug candidates and receipts for sleep problems can be identified separately for normal and AD Drosophila populations, outlining Drosophila’s potential in drug screening tests in other populations if combined with the use of other genetic disease tools.

Molecular and cellular mechanisms underlying the pathogenesis of Alzheimer's disease

Alzheimer’s disease (AD) is the most common neurodegenerative disorder seen in age-dependent dementia. There is currently no effective treatment for AD, which may be attributed in part to lack of a clear underlying mechanism. Studies within the last few decades provide growing evidence for a central role of amyloid β (Aβ) and tau, as well as glial contributions to various molecular and cellular pathways in AD pathogenesis. Herein, we review recent progress with respect to Aβ- and tau-associated mechanisms, and discuss glial dysfunction in AD with emphasis on neuronal and glial receptors that mediate Aβ-induced toxicity. We also discuss other critical factors that may affect AD pathogenesis, including genetics, aging, variables related to environment, lifestyle habits, and describe the potential role of apolipoprotein E (APOE), viral and bacterial infection, sleep, and microbiota. Although we have gained much towards understanding various aspects underlying this devastating neurodegenerative disorder, greater commitment towards research in molecular mechanism, diagnostics and treatment will be needed in future AD research.

Effects of exercise on sleep in neurodegenerative disease

As the population ages, the incidence and prevalence of neurodegenerative disorders will continue to increase. Persons with neurodegenerative disease frequently experience sleep disorders, which not only affect quality of life, but potentially accelerate progression of the disease. Unfortunately, pharmacological interventions are often futile or have adverse effects. Therefore, investigation of non-pharmacological interventions has the potential to expand the treatment landscape for these disorders. The last decade has observed increasing recognition of the beneficial role of exercise in brain diseases, and neurodegenerative disorders in particular. In this review, we will focus on the therapeutic role of exercise for sleep dysfunction in four neurodegenerative diseases, namely Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. Available data suggest that exercise may have the potential to improve sleep disorders and attenuate neurodegeneration, particularly in Alzheimer's disease and Parkinson's disease. However, additional research is required in order to understand the most effective exercise therapy for these indications; the best way to monitor the response to interventions; the influence of exercise on sleep dysfunction in Huntington's disease and amyotrophic lateral sclerosis; and the mechanisms underlying exercise-induced sleep modifications.

Sleep Health: An Opportunity for Public Health to Address Health Equity

The concept of sleep health provides a positive holistic framing of multiple sleep characteristics, including sleep duration, continuity, timing, alertness, and satisfaction. Sleep health promotion is an underrecognized public health opportunity with implications for a wide range of critical health outcomes, including cardiovascular disease, obesity, mental health, and neurodegenerative disease. Using a socioecological framework, we describe interacting domains of individual, social, and contextual influences on sleep health. To the extent that these determinants of sleep health are modifiable, sleep and public health researchers may benefit from taking a multilevel approach for addressing disparities in sleep health. For example, in addition to providing individual-level sleep behavioral recommendations, health promotion interventions need to occur at multiple contextual levels (e.g., family, schools, workplaces, media, and policy). Because sleep health, a key indicator of overall health, is unevenly distributed across the population, we consider improving sleep health a necessary step toward achieving health equity.

Healthy Eating, Physical Activity, and Sleep Hygiene (HEPAS) as the Winning Triad for Sustaining Physical and Mental Health in Patients at Risk for or with Neuropsychiatric Disorders: Considerations for Clinical Practice

Neuropsychiatric disorders stem from gene-environment interaction and their development can be, at least in some cases, prevented by the adoption of healthy and protective lifestyles. Once full blown, neuropsychiatric disorders are prevalent conditions that patients live with a great burden of disability. Indeed, the determinants that increase the affliction of neuropsychiatric disorders are various, with unhealthy lifestyles providing a significant contribution in the interplay between genetic, epigenetic, and environmental factors that ultimately represent the pathophysiological basis of these impairing conditions. On one hand, the adoption of Healthy Eating education, Physical Activity programs, and Sleep hygiene promotion (HEPAS) has the potential to become one of the most suitable interventions to reduce the risk to develop neuropsychiatric disorders, while, on the other hand, its integration with pharmacological and psychological therapies seems to be essential in the overall management of neuropsychiatric disorders in order to reduce the disability and improve the quality of life of affected patients. We present an overview of the current evidence in relation to HEPAS components in the prevention and management of neuropsychiatric disorders and provide suggestions for clinical practice.

Sleep and Circadian Medicine

Fundamental aspects of neurobiology are time-of-day regulated. Therefore, it is not surprising that neurodegenerative and psychiatric diseases are accompanied by sleep and circadian rhythm disruption. Although the direction of causation remains unclear, abnormal sleep-wake patterns often occur early in disease, exacerbate progression, and are a common primary complaint from patients. Circadian medicine incorporates knowledge of 24-hour biological rhythms to improve treatment. This article highlights how research and technologic advances in circadian biology might translate to improved patient care.

Sleep architecture changes in the APP23 mouse model manifest at onset of cognitive deficits

Alzheimer's disease (AD), which accounts for most of the dementia cases, is, aside from cognitive deterioration, often characterized by the presence of non-cognitive symptoms such as activity and sleep disturbances. AD patients typically experience increased sleep fragmentation, excessive daytime sleepiness and night-time insomnia. Here, we sought to investigate the link between sleep architecture, cognition and amyloid pathology in the APP23 amyloidosis mouse model for AD. By means of polysomnographic recordings the sleep-wake cycle of freely-moving APP23 and wild-type (WT) littermates of 3, 6 and 12 months of age was examined. In addition, ambulatory cage activity was assessed by interruption of infrared beams surrounding the home cage. To assess visuo-spatial learning and memory a hidden-platform Morris-type Water Maze (MWM) experiment was performed. We found that sleep architecture is only slightly altered at early stages of pathology, but significantly deteriorates from 12 months of age, when amyloid plaques become diffusely present. APP23 mice of 12 months old had quantitative reductions of NREM and REM sleep and were more awake during the dark phase compared to WT littermates. These findings were confirmed by increased ambulatory cage activity during that phase of the light-dark cycle. No quantitative differences in sleep parameters were observed during the light phase. However, during this light phase, the sleep pattern of APP23 mice was more fragmented from 6 months of age, the point at which also cognitive abilities started to be affected in the MWM. Sleep time also positively correlated with MWM performance. We also found that spectral components in the EEG started to alter at the age of 6 months. To conclude, our results indicate that sleep architectural changes arise around the time the first amyloid plaques start to form and cognitive deterioration becomes apparent. These changes start subtle, but gradually worsen with age, adequately mimicking the clinical condition.

Dietary Protein and Amino Acid Intake: Links to the Maintenance of Cognitive Health

With the rapid growth in the aging population, there has been a subsequent increase in the rates of Alzheimer's disease and related dementias (ADRD). To combat these increases in ADRD, scientists and clinicians have begun to place an increased emphasis on preventative methods to ameliorate disease rates, with a primary focus area on dietary intake. Protein/amino acid intake is a burgeoning area of research as it relates to the prevention of ADRD, and consumption is directly related to a number of disease-related risk factors as such low-muscle mass, sleep, stress, depression, and anxiety. As a result, the role that protein/amino acid intake plays in affecting modifiable risk factors for cognitive decline has provided a robust area for scientific exploration; however, this research is still speculative and specific mechanisms have to be proven. The purpose of this review is to describe the current understanding of protein and amino acids and the preventative roles they play with regard to ADRD, while providing future recommendations for this body of research. Additionally, we will discuss the current recommendations for protein intake and how much protein older adults should consume in order to properly manage their long-term risk for cognitive decline.

Effects of Light Treatment on Sleep, Cognition, Mood, and Behavior in Alzheimer's Disease: A Systematic Review

BACKGROUND

Bright light treatment is a therapeutic intervention mainly used to treat sleep and circadian disturbances in Alzheimer's disease (AD) patients. Recently, a handful of studies also focused on the effect on cognition and behavior. Conflicting findings are reported in the literature, and no definite conclusions have been drawn about its specific therapeutic effect.

SUMMARY

The aim of this review is to provide a critical evaluation of available evidence in this field, highlighting the specific characteristics of effective bright light treatment. Eligible studies were required to assess at least one of the following outcome measures: sleep, cognition, mood, and/or behavior (e.g., depression, agitation). A total of 32 articles were included in this systematic review and identified as research intervention studies about light treatment in AD. The quality of the papers was evaluated based on the US Preventive Service Task Force guidelines. Key Messages: Overall, the current literature suggests that the effects of light treatment in AD patients are mixed and may be influenced by several factors, but with a general trend toward a positive effect. Bright light seems to be a promising intervention treatment without significant adverse effects; therefore, further well-designed randomized controlled trials are needed taking into account the highlighted recommendations.

Alteration in sleep architecture and electroencephalogram as an early sign of Alzheimer's disease preceding the disease pathology and cognitive decline

OBJECTIVE

The present work aims to evaluate the significance of sleep disturbance and electroencephalogram (EEG) alteration in the early stage of Alzheimer's disease (AD).

BACKGROUND AND RATIONALE

Sleep disturbance is common in patients with AD. It is not known if it can occur at the early stage of AD and if EEG recording may help identify the early sign of the disease.

HISTORICAL EVOLUTION

Sleep disturbance in AD has generally been considered as late consequence of the neurodegenerative process. A growing body of evidence has suggested that the sleep disturbance may occur at the early stage of AD.

UPDATED HYPOTHESIS

Based on the previous epidemiologic studies and our recent findings, we propose that sleep disturbance may play an important role in the development of AD. Sleep EEG changes may serve as a valuable early sign for AD in the prepathological stage.

EARLY EXPERIMENTAL DATA

Our data suggested that AβPP^swe/PS1^ΔE9 transgenic AD mice at preplaque stage (3 and 4 months of age) exhibited different profile of sleep architecture and sleep EEG, which preceded the cognitive deficit and AD neuropathology.

FUTURE EXPERIMENTS AND VALIDATION STUDIES

Future experiments should focus on sleep EEG changes in patients with mild cognitive impairment and early stage of AD. Follow-up studies in high-risk population of the elderly are equally important. In addition, the exact molecular mechanism underlying the sleep disturbance should be thoroughly investigated.

MAJOR CHALLENGES FOR THE HYPOTHESIS

Studies on human participants with early stage of AD, especially the follow-up studies on the presymptomatic elderly in a large population, are difficult and time-consuming.

LINKAGE TO OTHER MAJOR THEORIES

Our hypothesis may link previous theories to establish a bidirectional relationship between sleep disorders and AD, which may finally form a new schematic mechanism to understand the disease pathogenesis and disease progression.

The Effects of Yoga on Patients with Mild Cognitive Impairment and Dementia: A Scoping Review

Yoga is an ancient mind body practice. Although yoga has been used as a complementary health approach for enhancing wellness and addressing a variety of health issues, little is known about the impact of yoga on cognitive functioning in adults with mild cognitive impairment (MCI) and dementia. We conducted a literature review to examine the impact of yoga on persons with MCI and dementia. Eight studies were identified that reported on yoga as either the primary intervention or one component of a multi-component intervention in samples of persons with MCI or dementia. Results suggest that yoga may have beneficial effects on cognitive functioning, particularly on attention and verbal memory. Further, yoga may affect cognitive functioning through improved sleep, mood, and neural connectivity. There are a number of limitations of the existing studies, including a lack of intervention details, as well as variability in the frequency/duration and components of the yoga interventions. A further complicating issue is the role of various underlying etiologies of cognitive impairment. Despite these limitations, providers may consider recommending yoga to persons with MCI or dementia as a safe and potentially beneficial complementary health approach.

Relevance of electroencephalogram assessment in amyloid and tau pathology in rat

In order to contribute to a better knowledge on the relationship between amyloid and tau pathology, and electroencephalography (EEG) disturbances, the aim of this study was to evaluate the effects of injection of beta amyloid Abeta(1-42) peptide, tau (a recombinant AAV (Adeno-Associated Virus) containing the human transgene tau with the P301 L mutation on rats and the combination of both, on the power of brain's rhythm (delta, theta, alpha, beta and gamma waves) during the different sleep/wake states of animals by EEG recording. Currently, no preclinical studies explore the effect of the tau pathology on EEG. The experimentations were performed 3 weeks and 3 months post injections. Beta amyloid deposits and hyperphosphorylated Tau are observed by immunohistofluorescence, only in the hippocampus. Furthermore, using a radial arm water maze, the main effect was observed on working memory which was significantly impaired in Abeta-Tau group only 3 months post injections. However, on EEG, as early as the 3^rd week, an overall decrease of the EEG bands power was observed in the treated groups, particularly the theta waves during the rapid eye movement (REM) sleep. Beta amyloid was mainly involved in these perturbations. Obviously, EEG seems to be an interesting tool in the early diagnostic of amyloid and tau pathologies, with a good sensitivity and the possibility to perform a follow up during a large period.

Hypercapnic and Hypoxic Respiratory Response During Wakefulness and Sleep in a Streptozotocin Model of Alzheimer's Disease in Rats

Besides the typical cognitive decline, patients with Alzheimer's disease (AD) develop disorders of the respiratory system, such as sleep apnea, shortness of breath, and arrhythmias. These symptoms are aggravated with the progression of the disease. However, the cause and nature of these disturbances are not well understood. Here, we treated animals with intracerebroventricular streptozotocin (STZ, 2 mg/kg), a drug that has been described to cause Alzheimer-like behavioral and histopathological impairments. We measured ventilation (V̇E), electroencephalography, and electromyography during normocapnia, hypercapnia, and hypoxia in Wistar rats. In addition, we performed western blot analyses for phosphorylated tau, total tau, and amyloid-β (Aβ) peptide in the locus coeruleus (LC), retrotrapezoid nucleus, medullary raphe, pre-Bötzinger/Bötzinger complex, and hippocampus, and evaluated memory and learning acquisition using the Barnes maze. STZ treatment promoted memory and learning deficits and increased the percentage of total wakefulness during normocapnia and hypercapnia due to a reduction in the length of episodes of wakefulness. CO2-drive to breathe during wakefulness was increased by 26% in STZ-treated rats due to an enhanced tidal volume, but no changes in V̇E were observed in room air or hypoxic conditions. The STZ group also showed a 70% increase of Aβ in the LC and no change in tau protein phosphorylation. In addition, no alteration in body temperature was observed. Our findings suggest that AD animals present an increased sensitivity to CO2 during wakefulness, enhanced Aβ in the LC, and sleep disruption.

Corticosteroid therapy exacerbates the reduction of melatonin in multiple sclerosis

OBJECTIVES

Corticosteroid therapy is employed in multiple sclerosis (MS), a neurological abnormality characterized by an inflammatory process. Melatonin, a potent sleep-promoting and circadian phase regulatory hormone, is produced mainly in the pineal gland whose inhibition leads to sleep disturbances.

METHODS

In this study, methylprednisolone (MP) corticosteroid treatment was used in an acute experimental autoimmune encephalomyelitis (EAE) rat model (intraperitoneal, 30 mg/kg) and in MS patients (intravenous, 1000 mg/day), followed by assessing melatonin serum levels.

KEY FINDINGS

Results showed that mean clinical scores were significantly improved in MP- versus PBS-treated EAE rats (1.5 vs 4.1, respectively). In addition, MP was found to induce a significant decrease in serum IFN-γ, whereas IL-4 levels were significantly increased, in comparison to PBS-treated EAE rats. The ratio of IFN-γ/IL-4, which acts as an indicator of Th-1/Th-2, was significantly lower in MP treated, compared to PBS treated EAE rats or controls. Moreover, serum levels of melatonin showed a significant decrease in the MP group, compared to normal rats. Moreover, MP therapy for 1 or 2 days resulted in a significant reduction of melatonin serum levels in MS patients.

CONCLUSIONS

Since corticosteroids cause a reduction in melatonin serum levels, an important hormone in sleep regulation, their prescription to MS patients should be carefully considered. Corticosteroids could be a cause of insomnia and sleep disturbance in patients receiving this type of medication.

Sleep, Cognitive impairment, and Alzheimer's disease: A Systematic Review and Meta-Analysis

Study Objectives

Mounting evidence implicates disturbed sleep or lack of sleep as one of the risk factors for Alzheimer's disease (AD), but the extent of the risk is uncertain. We conducted a broad systematic review and meta-analysis to quantify the effect of sleep problems/disorders on cognitive impairment and AD.

Methods

Original published literature assessing any association of sleep problems or disorders with cognitive impairment or AD was identified by searching PubMed, Embase, Web of Science, and the Cochrane library. Effect estimates of individual studies were pooled and relative risks (RR) and 95% confidence intervals (CI) were calculated using random effects models. We also estimated the population attributable risk.

Results

Twenty-seven observational studies (n = 69216 participants) that provided 52 RR estimates were included in the meta-analysis. Individuals with sleep problems had a 1.55 (95% CI: 1.25-1.93), 1.65 (95% CI: 1.45-1.86), and 3.78 (95% CI: 2.27-6.30) times higher risk of AD, cognitive impairment, and preclinical AD than individuals without sleep problems, respectively. The overall meta-analysis revealed that individuals with sleep problems had a 1.68 (95% CI: 1.51-1.87) times higher risk for the combined outcome of cognitive impairment and/or AD. Approximately 15% of AD in the population may be attributed to sleep problems.

Conclusion

This meta-analysis confirmed the association between sleep and cognitive impairment or AD and, for the first time, consolidated the evidence to provide an "average" magnitude of effect. As sleep problems are of a growing concern in the population, these findings are of interest for potential prevention of AD.

Associations between Brain Perfusion and Sleep Disturbance in Patients with Alzheimer's Disease

Background and Purpose

Methods

Results

Conclusions

Mechanisms of Melatonin in Alleviating Alzheimer's Disease

Alzheimer's disease (AD) is a chronic, progressive and prevalent neurodegenerative disease characterized by the loss of higher cognitive functions and an associated loss of memory. The thus far "incurable" stigma for AD prevails because of variations in the success rates of different treatment protocols in animal and human studies. Among the classical hypotheses explaining AD pathogenesis, the amyloid hypothesis is currently being targeted for drug development. The underlying concept is to prevent the formation of these neurotoxic peptides which play a central role in AD pathology and trigger a multispectral cascade of neurodegenerative processes post-aggregation. This could possibly be achieved by pharmacological inhibition of β- or γ-secretase or stimulating the nonamyloidogenic α-secretase. Melatonin the pineal hormone is a multifunctioning indoleamine. Production of this amphiphilic molecule diminishes with advancing age and this decrease runs parallel with the progression of AD which itself explains the potential benefits of melatonin in line of development and devastating consequences of the disease progression. Our recent studies have revealed a novel mechanism by which melatonin stimulates the nonamyloidogenic processing and inhibits the amyloidogenic processing of β-amyloid precursor protein (βAPP) by stimulating α -secretases and consequently down regulating both β- and γ-secretases at the transcriptional level. In this review, we discuss and evaluate the neuroprotective functions of melatonin in AD pathogenesis, including its role in the classical hypotheses in cellular and animal models and clinical interventions in AD patients, and suggest that with early detection, melatonin treatment is qualified to be an anti-AD therapy.

Bright Light Treatment Has Limited Effect in Subjects over 55 Years with Mild Early Morning Awakening

31 subjects, age 55 yr. or older, suffering from mild early morning awakening were randomized to either a bright light (10,000 lux) or to a red dim light placebo condition (200 lux). Light exposure took place in the evening in the patients' homes, 60 to 30 min. before bedtime and lasted for 3 wk. The subjects kept a sleep diary for 2 wk. and wore an actigraph for 1 wk. both before treatment and at post-treatment. Of the eight sleep diary outcome variables, significant effects that could be attributed to the light treatment were only detected for time spent in bed after final morning awakening. None of the six actigraph outcome variables yielded any significant effect of the light therapy. Explanations for the limited therapeutic effects of bright light treatment obtained in the present study are discussed, such as the criteria defining early morning awakening, the selection procedure, problems with compliance, age of the sample, and the dose of light. The lack of an objective circadian marker in this study could represent a problem concerning the timing of the light exposure. Despite the limited success of bright light therapy in this study, bright light therapy should still be considered as a treatment option for early morning awakening.

Do Circadian Rhythms Draw the Patterns of Sustained Mental Vigor and Ailment?

Preclinical Research Circadian rhythms are fundamental processes in all cells that coordinate a variety of cellular functions related to a specific time of the day. Disruption of circadian rhythms markedly impacts homeostasis. In this Commentary, we present data that disruption of circadian rhythm may lead to the pathogenesis of neurodegenerative states. In this context, we further argue that there is an urgent need of developing new generations of compounds, chronobiotics, to modulate the molecular substrates of circadian timing system. Chronobiotics conceptually offer an effective way for restoration and protection from the consequences of the circadian disruption. We also briefly discuss whether dysfunctional circadian rhythms are a major driver of aging. Drug Dev Res 77 : 469-473, 2016. © 2016 Wiley Periodicals, Inc.

The Synergistic Relationship between Alzheimer's Disease and Sleep Disorders: An Update

Sleep disorders are frequently reported in Alzheimer's disease (AD), with a significant impact on patients and caregivers and a major risk factor for early institutionalization. Although changes in sleep organization are a hallmark of the normal aging processes, sleep macro- and micro-architectural alterations are more evident in patients affected by AD. Degeneration of neural pathways regulating sleep-wake patterns and sleep architecture may contribute to sleep alterations. In return, several recent studies suggested that common sleep disorders may precede clinical symptoms of dementia and represent risk factors for cognitive decline, through impairment of sleep-dependent memory consolidation processes. Thus, a close relationship between sleep disorders and AD has been largely hypothesized. Here, sleep alterations in AD and its pre-dementia stage, mild cognitive impairment, and their complex interactions are reviewed.

[Nighttime restlessness in people with dementia in residential care: an explorative field study]

Nighttime restlessness in dementia is an underestimated problem. Although little is known about the prevalence and not every person with dementia struggles with it, nighttime restlessness puts a heavy burden on the persons themselves and their caregivers.This field study explores nighttime restlessness in nursing homes based on two research questions: (1) What is nighttime restlessness according to professional caregivers? and (2) How is nighttime restlessness managed?Data were collected through diaries, interviews with caregivers and one night of observation in eight nursing homes.Wandering and screaming seem to be the most prevalent nighttime agitated behaviours. Caregivers identify many possible causes, but spatial and sensory factors, such as light or noise, were rarely mentioned spontaneously. The observations highlighted that a lot of light and noise is prominent and this might be causing nighttime restlessness.Caregivers try several strategies: for example talking with the resident, put on a light and apply medication or physical restraints.The management of nighttime restlessness requires a holistic approach. Caregivers' attention for and efforts to ameliorate the spatial and sensory environment in the management of nighttime restlessness are limited.

Sleep in the Context of Healthy Aging and Psychiatric Syndromes

Humans spend approximately one-third of their lives asleep. Whether due to evolutionary or ontogenetic factors, sleep and psychiatric disorders change with age. Although much of sleep remains an enigma, sleep research is experiencing an exponential increase in its understanding of the causes, correlates, and consequences of sleep disturbances. Although the relationship between age-related sleep and psychiatric conditions is a common clinical observation, empirical investigations remain scarce. Thus, treating patients with symptoms of sleep disorders in the context of psychiatric conditions remains a challenge. This article reviews the state-of-the-science of sleep disorders in the context of psychiatric conditions in late-life.

Influence of Sleep on Quality of Life Among Hospital Nurses

Introduction

Sleep disorders are the cause of morbidity and mortality and can decrease functional capacity and quality of life. Nurses, especially those working irregular or night shifts, are at risk for developing sleep disorders. The present study aims to determine the relationship between sleep quality and health-related quality of life (HRQOL) as well as quantitative and subjective aspects of sleep quality in nurses.

Methods

This cross-sectional study was conducted on 1456 nurses working in 11 hospitals in Shiraz and Tehran (Iran) in 2014. Structured questionnaires (Pittsburg Sleep Quality Index [PSQI] and Medical Outcomes Study Short Form-36 Survey [SF-36]) were used to collect data on participants’ demographic characteristics, sleep quality, and health-related quality of life. Chi-square and independent samples t-test were employed for statistical analysis.

Results

Mean age of participants was 30.81 ± 7.8, and most of them were female (89.04%) and poor sleepers. Long-duration sleepers slept for more than 9.8 h/night, and they obtained higher scores than short-duration sleepers (<4.5 h/night) in all SF-36 domains. The study results showed that increased quality of life was significantly related to health-related quality of life.

Conclusions

This study showed strong evidence that sleep disorders, such as poor quality and short duration of sleep, are negatively associated with HRQOL. Therefore, developing systemic strategies to cope with the problem seems to be necessary.

The Relationship Between Sleep Disturbances and Psychiatric Disorders: Introduction and Overview

Changes in the psychiatric diagnostic guidelines with the transition from Diagnostic and Statistical Manual of Mental Disorders (DSM)-IV to DSM-V include acknowledgment that primary sleep disorders such as insomnia can occur in conjunction with medical and psychiatric disorders. This change in viewpoint regarding the definition of primary sleep disorders opens the way to the recognition that patients with psychiatric disorders demonstrate a high prevalence of sleep disturbances, with complaints of insomnia and excessive daytime sleepiness being especially commonly reported. Recent investigations have pointed to a bidirectional relationship between sleep disturbances and psychiatric disorders.

The effects of light therapy on sleep problems: A systematic review and meta-analysis

Although bright light therapy seems a promising treatment for sleep problems, research shows inconclusive results. This meta-analysis is the first to systematically review the effect of light therapy on sleep problems in general and on specific types of sleep problems in particular (circadian rhythm sleep disorders, insomnia, sleep problems related to Alzheimer's disease and dementia). Fifty-three studies with a total of 1154 participants were included. Overall effects and effects on separate circadian and sleep outcomes were examined. We calculated Hedges' g effect sizes and we investigated the effects of twelve moderators (design-related, treatment-related, participant-related). Light therapy was found effective in the treatment of sleep problems in general (g = 0.39), and for circadian rhythm sleep disorders (g = 0.41), insomnia (g = 0.47), and sleep problems related to Alzheimer's disease/dementia (g = 0.30) specifically. For circadian rhythm sleep disorders, effects were smaller for randomised controlled trials. For insomnia, we found larger effects for studies using a higher light intensity, and for sleep problems related to Alzheimer's disease/dementia larger effects were found for studies with more female participants. There was indication of publication bias. To conclude, light therapy is effective for sleep problems in general, particularly for circadian outcomes and insomnia symptoms. However, most effect sizes are small to medium.