How non-rapid eye movement sleep and Alzheimer pathology are linked

Alzheimer's disease(AD)is a multifactorial neurodegenerative disorder characterized by the presence of senile plaques and neurofibrillary tangles.Research attempts to identify characteristic factors that are associated with the presence of the AD pathology on the one hand and that increase the risk of developing AD on the other.Changes in non-rapid eye movement(NREM)sleep may meet both requirements for various reasons.First,NREM-sleep is important for optimal memory function.In addition,studies report that the presence of AD pathology is associated with NREM-sleep changes.Finally,more and more results appear to suggest that sleep problems are not only a symptom of AD but can also increase the risk of AD.Several of these studies suggest that it is primarily a lack of NREM-sleep that is responsible for this increased risk.However,the majority investigated sleep only through subjective reporting,as a result of which NREMsleep could not be analyzed separately.The aim of this literature study is therefore to present the results of the studies that relate the AD pathology and NREM-sleep(registered by electroencephalography).Furthermore,we try to evaluate whether NREM-sleep analysis could be used to support the diagnosis of AD and whether NREM-sleep deficiency could be a causal factor in the development of AD.

Sleep disorders in Alzheimer’s disease:the predictive roles and potential mechanisms

Sleep disorders are common in patients with Alzheimer’s disease,and can even occur in patients with amnestic mild cognitive impairment,which appears before Alzheimer’s disease.Sleep disorders further impair cognitive function and accelerate the accumulation of amyloid-βand tau in patients with Alzheimer’s disease.At present,sleep disorders are considered as a risk factor for,and may be a predictor of,Alzheimer’s disease development.Given that sleep disorders are encountered in other types of dementia and psychiatric conditions,sleep-related biomarkers to predict Alzheimer’s disease need to have high specificity and sensitivity.Here,we summarize the major Alzheimer’s disease-specific sleep changes,including abnormal non-rapid eye movement sleep,sleep fragmentation,and sleep-disordered breathing,and describe their ability to predict the onset of Alzheimer’s disease at its earliest stages.Understanding the mechanisms underlying these sleep changes is also crucial if we are to clarify the role of sleep in Alzheimer’s disease.This paper therefore explores some potential mechanisms that may contribute to sleep disorders,including dysregulation of the orexinergic,glutamatergic,andγ-aminobutyric acid systems and the circadian rhythm,together with amyloid-βaccumulation.This review could provide a theoretical basis for the development of drugs to treat Alzheimer’s disease based on sleep disorders in future work.

Increased Arousal Levels and Decreased Sleep by Brain Music in Rats

More and more studies have been reported on whether music and other types of auditory stimulation would improve the quality of sleep. Many of these studies have found significant results, but others argue that music is not significantly better than the tones or control conditions in improving sleep. For further understanding the relationship between music and sleep or music and arousal, the present study therefore examines the effects of brain music on sleep and arousal by means of biofeedback. The music is from the transformation of rapid eye movement （REM） sleep electroencephalogram （EEG） of rats using an algorithm in the Chengdu Brain Music （CBM） system. When the brain music was played back to rats, EEG data were recorded to assess the efficacy of music to induce or improve sleep, or increase arousal levels by sleep staging, etc. Our results demonstrate that exposure to the brain music increases arousal levels and decreases sleep in rats, and the underlying mechanism of decreased non-rapid eye movement （NREM） and REM sleep may be different.