Aging-related sleep changes

Fragmentation and stability of circadian activity rhythms predict mortality: the Rotterdam study

Circadian rhythms and sleep patterns change as people age. Little is known about the associations between circadian rhythms and mortality rates. We investigated whether 24-hour activity rhythms and sleep characteristics independently predicted mortality. Actigraphy was used to determine the stability and fragmentation of the 24-hour activity rhythm in 1,734 persons (aged 45-98 years) from the Rotterdam Study (2004-2013). Sleep was assessed objectively using actigraphy and subjectively using sleep diaries to estimate sleep duration, sleep onset latency, and waking after sleep onset. The mean follow-up time was 7.3 years; 154 participants (8.9%) died. Sleep measures were not related to mortality after adjustment for health parameters. In contrast, a more stable 24-hour activity rhythm was associated with a lower mortality risk (per 1 standard deviation, hazard ratio = 0.83, 95% confidence interval: 0.71, 0.96), and a more fragmented rhythm was associated with a higher mortality risk (per 1 standard deviation, hazard ratio = 1.22, 95% confidence interval: 1.04, 1.44). Low stability and high fragmentation of the 24-hour activity rhythm predicted all-cause mortality, whereas estimates from actigraphy and sleep diaries did not. Disturbed circadian activity rhythms reflect age-related alterations in the biological clock and could be an indicator of disease.

Buying time: a rationale for examining the use of circadian rhythm and sleep interventions to delay progression of mild cognitive impairment to Alzheimer's disease

As of 2010, the worldwide economic impact of dementia was estimated at $604 billion USD; and without discovery of a cure or effective interventions to delay disease progression, dementia's annual global economic impact is expected to surpass $1 trillion USD as early as 2030. Alzheimer's disease (AD) is the leading cause of dementia accounting for over 75% of all cases. Toxic accumulation of amyloid beta (Aβ), either by overproduction or some clearance failure, is thought to be an underlying mechanism of the neuronal cell death characteristic of AD-though this amyloid hypothesis has been increasingly challenged in recent years. A compelling alternative hypothesis points to chronic neuroinflammation as a common root in late-life degenerative diseases including AD. Apolipoprotein-E (APOE) genotype is the strongest genetic risk factor for AD: APOE-ε4 is proinflammatory and individuals with this genotype accumulate more Aβ, are at high risk of developing AD, and almost half of all AD patients have at least one ε4 allele. Recent studies suggest a bidirectional relationship exists between sleep and AD pathology. Sleep may play an important role in Aβ clearance, and getting good quality sleep vs. poor quality sleep might reduce the AD risk associated with neuroinflammation and the ε4 allele. Taken together, these findings are particularly important given the sleep disruptions commonly associated with AD and the increased burden disrupted sleep poses for AD caregivers. The current review aims to: (1) identify individuals at high risk for dementia who may benefit most from sleep interventions; (2) explore the role poor sleep quality plays in exacerbating AD type dementia; (3) examine the science of sleep interventions to date; and (4) provide a road map in pursuit of comprehensive sleep interventions, specifically targeted to promote cognitive function and delay progression of dementia.

Aging and sleep in Williams syndrome: accelerated sleep deterioration and decelerated slow wave sleep decrement

Specific developmental and aging trajectories characterize sleep electroencephalogram (EEG) of typically developing (TD) subjects. Williams syndrome (WS) is marked by sleep alterations and accelerated aging of several anatomo-functional and cognitive measures. Here we test the hypothesis of a premature aging of sleep in WS. Age-related changes of home recorded sleep EEG of 42 subjects (21 WS, 21 age- and gender matched TD subjects, age: 6-29 years) were tested by Pearson correlations and homogeneity-of-slopes analysis. Typical developmental/aging effects of sleep EEGs were observed in TD subjects. Accelerated aging in WS was confirmed by overall sleep/wake measures. Specifically, premature aging was evident in accelerated age-dependent declines in WS subjects' sleep efficiency, as well as in steeper age-related rises in wakefulness and wake after sleep onset (WASO) of the WS group. In contrast, NREM sleep-related measures indicated atypical decelerations of the developmental trends of WS subjects, characterized by the slowing down of the age-related slow wave sleep (SWS) declines mirrored by the lack of age-dependent increase in Stage 2 (S2) sleep. Age-effects in sleep EEG power spectra were not different among the groups. Objectively measured sleep disruption of subjects with WS is age-dependent and increasing with age. Moreover, these data suggest atypical pre- and postpubertal neural development in WS, with sleep/wake balance and REM sleep time indicating accelerated aging while NREM sleep composition revealing signs of an as yet unidentified, perhaps compensatory developmental delay.

Trends and determinants of time in bed in Geneva, Switzerland

STUDY OBJECTIVES

There is limited information regarding sleep duration and determinants in Switzerland. We aimed to assess the trends and determinants of time in bed as a proxy for sleep duration in the Swiss canton of Geneva.

METHODS

Data from repeated, independent cross-sectional representative samples of adults (≥ 18 years) of the Geneva population were collected between 2005 and 2011. Self-reported time in bed, education, monthly income, and nationality were assessed by questionnaire.

RESULTS

Data from 3,853 participants (50% women, 51.7 ± 10.9 years) were analyzed. No significant trend was observed between 2005 and 2011 regarding time in bed or the prevalence of short (≤ 6 h/day) and long (> 9 h/day) time in bed. Elderly participants reported a longer time in bed (year-adjusted mean ± standard error: 7.67 ± 0.02, 7.82 ± 0.03, and 8.41 ± 0.04 h/day for 35-50, 50-65, and 65+ years, respectively, p < 0.001), while shorter time in bed was reported by non-Swiss participants (7.77 ± 0.03 vs. 7.92 ± 0.03 h/day for Swiss nationals, p < 0.001), participants with higher education (7.92 ± 0.02 for non-university vs. 7.74 ± 0.03 h/day for university, p < 0.001) or higher income (8.10 ± 0.04, 7.84 ± 0.03, and 7.70 ± 0.03 h/day for < 5,000 SFr; 5,000-9,500 SFr, and > 9,500 SFr, respectively, p < 0.001). Multivariable-adjusted polytomous logistic regression showed short and long time in bed to be positively associated with obesity and negatively associated with income.

CONCLUSION

In a Swiss adult population, sleep duration as assessed by time in bed did not change significantly between 2005 and 2011. Both clinical and socioeconomic factors influence time in bed.

Human longevity is associated with regular sleep patterns, maintenance of slow wave sleep, and favorable lipid profile

Some individuals are able to successfully reach very old ages, reflecting higher adaptation against age-associated effects. Sleep is one of the processes deeply affected by aging; however few studies evaluating sleep in long-lived individuals (aged over 85) have been reported to date. The aim of this study was to characterize the sleep patterns and biochemical profile of oldest old individuals (N = 10, age 85–105 years old) and compare them to young adults (N = 15, age 20–30 years old) and older adults (N = 13, age 60–70 years old). All subjects underwent full-night polysomnography, 1-week of actigraphic recording and peripheral blood collection. Sleep electroencephalogram spectral analysis was also performed. The oldest old individuals showed lower sleep efficiency and REM sleep when compared to the older adults, while stage N3 percentage and delta power were similar across the groups. Oldest old individuals maintained strictly regular sleep-wake schedules and also presented higher HDL-cholesterol and lower triglyceride levels than older adults. The present study revealed novel data regarding specific sleep patterns and maintenance of slow wave sleep in the oldest old group. Taken together with the favorable lipid profile, these results contribute with evidence to the importance of sleep and lipid metabolism regulation in the maintenance of longevity in humans.

Job burnout’s relationship with sleep difficulties in the presence of control variables: a self-report study

Burnout, as a work-related phenomenon, has negative consequences on employee functioning and is well documented. What is deserving of further investigation is how effort-recovery processes may be affected, in this instance, sleep. The purpose of this study was to investigate whether significant sleep difficulties are reported when employees report experienced burnout, while also controlling for age, gender, exercise, smoking habits, and treatment for depression. A cross-sectional survey design was used in data collection. The sample consisted of 734 participants with white collar positions in the financial industry of South Africa. Structural equation modelling methods were implemented in order to investigate the hypotheses. The results of the structural model indicated that burnout was significantly related to sleep difficulties, even in the presence of reported treatment for depression, and the other control variables. The correlations between burnout, treatment for depression, as well as sleep difficulties were all positive and practically significant. The results, recommendations, limitations, and practical implications of the study are discussed.

Sleep and aging: examining the effect of psychological symptoms and risk of sleep-disordered breathing

Controversy exists as to whether self-reported sleep quality declines with age, despite changes in sleep being accepted as part of normal aging. This study sought to investigate age-related differences in self-reported sleep quality, after controlling for conditions that are common with age, such as psychological symptoms and increased risk of sleep-disordered breathing (SDB). The Pittsburgh Sleep Quality Index (PSQI) was administered to a sample of 582 community adults (aged 18-89 years), and the association between age and 3 factors of the PSQI (sleep efficiency, perceived sleep quality, and daily disturbance), and global scores, was examined controlling for depression, anxiety, stress, gender, and SDB risk. Results indicate that (a) before controlling for covariates, there was no significant relation between age and all indexes of self-reported sleep quality, with the exception of sleep efficiency. However, once depression, gender, and SDB risk were controlled for, a significant, yet small, relation was revealed between older age and poorer global sleep quality; (b) there was no association between age and perceived sleep quality or daily disturbances before or after controlling for relevant covariates; and (c) depression, gender, and SDB risk were significant predictors of poorer sleep quality across the indexes but, in general, did not have a marked impact on the relation between age and sleep quality. In conclusion, results suggest that sleep problems are common across the lifespan, and that there were modest age-related differences in self-reported sleep quality, which were not due to depressed mood, gender, or risk of SDB.

Sleep disorders and acute nocturnal delirium in the elderly: a comorbidity not to be overlooked

Delirium is a disturbance of consciousness and cognition that results in a confusional state. It tends to fluctuate in intensity and is often observed in older patients. Sleep is a window of vulnerability for the occurrence of delirium and sleep disorders can play a role in its appearance. In particular, delirious episodes have been associated with obstructive sleep apnoea syndrome, which is reported to be frequent in the elderly. Hereby, we present a case-report documenting the sudden onset of a confusional state triggered by obstructive sleep apnoea-induced arousal, together with a review of the literature on the topic. We emphasise that, among the many pathogenic factors implicated in delirium, it is worth considering the possible link between nocturnal delirium and the occurrence of impaired arousals. Indeed, the complex confusional manifestations of delirium could be due, in part, to persistence of dysfunctional sleep activity resulting in an inability to sustain full arousal during behavioural wakefulness. Arousals can be triggered by sleep disturbances or other medical conditions. Clinicians should be aware that older patients may present disordered sleep patterns, and make investigation of sleep patterns and disorders potentially affecting sleep continuity a key part of their clinical workup, especially in the presence of cognitive comorbidities. Correct diagnosis and optimal treatment of sleep disorders and disrupted sleep can have a significant impact in the elderly, improving sleep quality and reducing the occurrence of abnormal sleep-related behaviours.

Aged rats are hypo-responsive to acute restraint: implications for psychosocial stress in aging

Cognitive processes associated with prefrontal cortex and hippocampus decline with age and are vulnerable to disruption by stress. The stress/stress hormone/allostatic load hypotheses of brain aging posit that brain aging, at least in part, is the manifestation of life-long stress exposure. In addition, as humans age, there is a profound increase in the incidence of new onset stressors, many of which are psychosocial (e.g., loss of job, death of spouse, social isolation), and aged humans are well-understood to be more vulnerable to the negative consequences of such new-onset chronic psychosocial stress events. However, the mechanistic underpinnings of this age-related shift in chronic psychosocial stress response, or the initial acute phase of that chronic response, have been less well-studied. Here, we separated young (3 month) and aged (21 month) male F344 rats into control and acute restraint (an animal model of psychosocial stress) groups (n = 9–12/group). We then assessed hippocampus-associated behavioral, electrophysiological, and transcriptional outcomes, as well as blood glucocorticoid and sleep architecture changes. Aged rats showed characteristic water maze, deep sleep, transcriptome, and synaptic sensitivity changes compared to young. Young and aged rats showed similar levels of distress during the 3 h restraint, as well as highly significant increases in blood glucocorticoid levels 21 h after restraint. However, young, but not aged, animals responded to stress exposure with water maze deficits, loss of deep sleep and hyperthermia. These results demonstrate that aged subjects are hypo-responsive to new-onset acute psychosocial stress, which may have negative consequences for long-term stress adaptation and suggest that age itself may act as a stressor occluding the influence of new onset stressors.

The influence of sex and age on the relationship between sleep duration and metabolic syndrome in Korean adults

AIMS

To investigate the influence of sex and age on the relationship between sleep duration and metabolic syndrome in a nationally representative population.

METHODS

We used data from the Korea National Health and Nutrition Examination Survey (2001-2010) and enrolled 24,511 participants aged 20-79 years. Sleep duration was categorized into five groups: ≤5, 6, 7 (referent), 8, and ≥9h/day. Age was categorized into three groups: younger (20-39y), middle-aged (40-59y), and older (60-79y). The association between sleep duration and metabolic syndrome was assessed in the total, separately in men and women, then in six groups based on sex and age.

RESULTS

The prevalence of metabolic syndrome by sleep category demonstrated a U-shaped pattern in the total population. However, after adjusting for age, education, occupation, exercise, smoking, alcohol, and body mass index, the prevalence of metabolic syndrome increased in long sleepers (OR 1.31; 95% CI 1.14-1.51) but not in short sleepers (OR 1.00; 95% CI 0.89-1.11). The relationship between sleep duration and metabolic syndrome varied by sex and age-long sleep (≥9h/day) was positively associated with metabolic syndrome only in younger (OR 2.13; 95% CI 1.38-3.28) and middle-aged (OR 1.63; 95% CI 1.21-2.21) women. Short sleep (≤5h/day) was not associated with metabolic syndrome in any sex and age groups. However, extremely short sleep (≤4h/day) was associated with metabolic syndrome in middle-aged men (OR 1.76, 95% CI 1.05-2.96).

CONCLUSION

These data suggest that sex and age significantly modify the relationship between sleep duration and metabolic syndrome.

Sleep disorders in older adults

Sleep pattern changes are considered normal as individuals age. However, changes in sleep patterns can ultimately affect the quality of life of many older adults. In addition, many sleep conditions are associated with an increase in morbidity and mortality. It is essential for clinicians to recognize sleep changes to lead to appropriate treatment. This article will focus on the assessment and interventions of sleep disorders in older adults.

Accelerated long-term forgetting in aging and intra-sleep awakenings

The architecture of sleep and the functional neuroanatomical networks subtending memory consolidation processes are both modified with aging, possibly leading to accelerated forgetting in long-term memory. We investigated associative learning and declarative memory consolidation processes in 16 young (18–30 years) and 16 older (65–75 years) healthy adults. Performance was tested using a cued recall procedure at the end of learning (immediate recall), and 30 min and 7 days later. A delayed recognition test was also administered on day 7. Daily sleep diaries were completed during the entire experiment. Results revealed a similar percentage of correct responses at immediate and 30-min recall in young and older participants. However, recall was significantly decreased 7 days later, with an increased forgetting in older participants. Additionally, intra-sleep awakenings were more frequent in older participants than young adults during the seven nights, and were negatively correlated with delayed recall performance on day 7 in the older group. Altogether, our results suggest a decline in verbal declarative memory consolidation processes with aging, eventually leading to accelerated long-term forgetting indicating that increased sleep fragmentation due to more frequent intra-sleep awakenings in older participants contribute to the reported age-related decline in long-term memory retrieval. Our results highlight the sensitivity of long-term forgetting measures to evidence consolidation deficits in healthy aging.

Polysomnographic and subjective sleep markers of mild cognitive impairment

STUDY OBJECTIVES

Growing evidence suggests that sleep disturbances precede by years the clinical onset of Alzheimer disease (AD). The goal of the current study is to determine whether changes in polysomnographic (PSG) sleep patterns accompany subjective sleep complaints in patients with mild cognitive impairment (MCI). We further examine whether meaningful changes in objective sleep physiology are predicted by self-reported sleep measures in MCI patients, and whether incipient neurodegeneration contributes to exacerbate sleep misperception.

DESIGN SETTING AND PARTICIPANTS

Overnight PSG recordings and self-reported sleep measures were obtained from 25 healthy elderly (HE) subjects and 25 patients with MCI at the sleep laboratory.

RESULTS

Both PSG and self-reported sleep measures confirmed that sleep is altered in patients with MCI. Whereas subjective sleep responses predicted fragmentation of slow wave sleep (SWS) in HE individuals, this relationship was not evident in MCI patients. Furthermore, patients with MCI showed significant discrepancies in the estimation of sleep onset latency when compared with HE subjects.

CONCLUSIONS

Sleep is significantly impaired in patients with mild cognitive impairment at both the objective and subjective level, which may be used as a surrogate marker of preclinical Alzheimer disease. Taken together, these findings aid in the development of novel therapeutic strategies devoted to improve sleep in the elderly population at risk of developing Alzheimer disease.

Age-dependent and gender-dependent regulation of hypothalamic-adrenocorticotropic-adrenal axis

Tightly regulated output of glucocorticoids is critical to maintaining immune competence, the structure of neurons, muscle, and bone, blood pressure, glucose homeostasis, work capacity, and vitality in the human and experimental animal. Age, sex steroids, gender, stress, body composition, and disease govern glucocorticoid availability through incompletely understood mechanisms. According to an ensemble concept of neuroendocrine regulation, successful stress adaptations require repeated incremental signaling adjustments among hypothalamic corticotropin-releasing hormone and arginine vasopressin, pituitary adrenocorticotropic hormone, and adrenal corticosteroids. Signals are transduced via (positive) feedforward and (negative) feedback effects. Age and gonadal steroids strongly modulate stress-adaptive glucocorticoid secretion by such interlinked pathways.

Cognitive training improves sleep quality and cognitive function among older adults with insomnia

Study Objectives

To investigate the effect of an eight-week, home-based, personalized, computerized cognitive training program on sleep quality and cognitive performance among older adults with insomnia.

Design

Participants (n = 51) were randomly allocated to a cognitive training group (n = 34) or to an active control group (n = 17). The participants in the cognitive training group completed an eight-week, home-based, personalized, computerized cognitive training program, while the participants in the active control group completed an eight-week, home-based program involving computerized tasks that do not engage high-level cognitive functioning. Before and after training, all participants' sleep was monitored for one week by an actigraph and their cognitive performance was evaluated.

Setting

Community setting: residential sleep/performance testing facility.

Participants

Fifty-one older adults with insomnia (aged 65–85).

Interventions

Eight weeks of computerized cognitive training for older adults with insomnia.

Results

Mixed models for repeated measures analysis showed between-group improvements for the cognitive training group on both sleep quality (sleep onset latency and sleep efficiency) and cognitive performance (avoiding distractions, working memory, visual memory, general memory and naming). Hierarchical linear regressions analysis in the cognitive training group indicated that improved visual scanning is associated with earlier advent of sleep, while improved naming is associated with the reduction in wake after sleep onset and with the reduction in number of awakenings. Likewise the results indicate that improved “avoiding distractions” is associated with an increase in the duration of sleep. Moreover, the results indicate that in the active control group cognitive decline observed in working memory is associated with an increase in the time required to fall asleep.

Conclusions

New learning is instrumental in promoting initiation and maintenance of sleep in older adults with insomnia. Lasting and personalized cognitive training is particularly indicated to generate the type of learning necessary for combined cognitive and sleep enhancements in this population.

Trial Registration

ClinicalTrials.gov NCT00901641

Sleep and immune function: glial contributions and consequences of aging

The reciprocal interactions between sleep and immune function are well-studied. Insufficient sleep induces innate immune responses as evidenced by increased expression of pro-inflammatory mediators in the brain and periphery. Conversely, immune challenges upregulate immunomodulator expression, which alters central nervous system-mediated processes and behaviors, including sleep. Recent studies indicate that glial cells, namely microglia and astrocytes, are active contributors to sleep and immune system interactions. Evidence suggests glial regulation of these interactions is mediated, in part, by adenosine and adenosine 5'-triphosphate actions at purinergic type 1 and type 2 receptors. Furthermore, microglia and astrocytes may modulate declines in sleep-wake behavior and immunity observed in aging.

Effect of chronic sleep restriction and aging on calcium signaling and apoptosis in the hippocampus of young and aged animals

Aging leads to progressive deterioration of physiological function and diminished responses to environmental stress. Organic and functional alterations are frequently observed in elderly subjects. Although chronic sleep loss is observed during senescence, little is known about the impact of insufficient sleep on cellular function in aging neurons. Disruption of neuronal calcium (Ca²⁺) signaling is related to impaired neuronal function and cell death. It has been hypothesized that sleep deprivation may compromise neuronal stability and induce cell death in young neurons; however, it is necessary to evaluate the impact of aging on this process. Therefore, the aim of this study was to evaluate the effects of chronic sleep restriction (CSR) on Ca²⁺ signaling and cell death in the hippocampus of young and aged animals. We found that glutamate and carbonyl cyanide-p-trifluoromethoxyphenylhydrazone (FCCP) induced a greater elevation in cytosolic Ca²⁺ ([Ca²⁺](c)) in hippocampal slices from aged rats subjected to CSR compared to age-matched controls. Interestingly, aged-matched controls showed a reduced Ca²⁺ response to glutamate and FCCP, relative to both CSR and control young animals. Apoptotic nuclei were observed in aged rats from both treatment groups; however, the profile of apoptotic nuclei in aged CSR rats was highly variable. Bax and Bcl-2 protein expression did not change with aging in the CSR groups. Our study indicates that aging promotes changes in Ca²⁺ signaling, which may also be affected by CSR. These age-dependent changes in Ca²⁺ signaling may increase cellular vulnerability during CSR and contribute to Ca²⁺ signaling dysregulation, which may ultimately induce cell death.

Age-related decline in controlled retrieval: the role of the PFC and sleep

Age-related cognitive impairments often include difficulty retrieving memories, particularly those that rely on executive control. In this paper we discuss the influence of the prefrontal cortex on memory retrieval, and the specific memory processes associated with the prefrontal cortex that decline in late adulthood. We conclude that preretrieval processes associated with preparation to make a memory judgment are impaired, leading to greater reliance on postretrieval processes. This is consistent with the view that impairments in executive control significantly contribute to deficits in controlled retrieval. Finally, we discuss age-related changes in sleep as a potential mechanism that contributes to deficiencies in executive control that are important for efficient retrieval. The sleep literature points to the importance of slow-wave sleep in restoration of prefrontal cortex function. Given that slow-wave sleep significantly declines with age, we hypothesize that age-related changes in slow-wave sleep could mediate age-related decline in executive control, manifesting a robust deficit in controlled memory retrieval processes. Interventions, like physical activity, that improve sleep could be effective methods to enhance controlled memory processes in late life.

Sleep duration and its correlates in middle-aged and elderly Chinese women: the Shanghai Women's Health Study

BACKGROUND

Abnormal sleep duration, either long or short, is associated with disease risk and mortality. Little information is available on sleep duration and its correlates among Chinese women.

METHODS

Using information collected from 68,832 women who participated in the Shanghai Women's Health Study (SWHS), we evaluated sleep duration and its correlations with sociodemographic and lifestyle factors, health status, and anthropometric measurements and their indexes using polynomial logistic regression.

RESULTS

The mean age of the study population was 59.6 years (SD=9.0; range: 44.6-79.9 years) at time of sleep duration assessment. Approximately 80% of women reported sleeping 6-8 h/day, 11.5% slept 5h or less, and 8.7% slept 9h or more. As expected, age was the strongest predictor for sleep duration and was negatively correlated with sleep duration. In general, sleep duration was positively associated with energy intake, intakes of total meat and fruits, body mass index (BMI), waist-hip ratio (WHR), and waist circumference (WC) after adjustment for age and other factors. Both short and long sleep duration were negatively associated with education level, family income, and leisure-time physical activity and positively associated with number of live births, history of night shift work, and certain chronic diseases, compared to sleep duration around 7 h/day (6.5-7.4h/day). Short sleep duration was related to tea consumption and passive smoking. Long sleep duration was related to menopausal status and marital status.

CONCLUSIONS

In this large, population-based study, we found that sleep duration among middle-aged and elderly Chinese women was associated with several sociodemographic and lifestyle factors and with disease status. The main limitation of the study is the cross-sectional design that does not allow us to draw any causal inference. However, this study provides information for future investigation into the nature of these associations so that recommendations can be developed to reduce sleep problems in middle-aged and elderly Chinese women. It also provides important information on potential confounders for investigation of sleep duration on health outcomes in this population.

Hippocampal CA1 transcriptional profile of sleep deprivation: relation to aging and stress

Background

Many aging changes seem similar to those elicited by sleep-deprivation and psychosocial stress. Further, sleep architecture changes with age suggest an age-related loss of sleep. Here, we hypothesized that sleep deprivation in young subjects would elicit both stress and aging-like transcriptional responses.

Methodology/Principal Findings

F344 rats were divided into control and sleep deprivation groups. Body weight, adrenal weight, corticosterone level and hippocampal CA1 transcriptional profiles were measured. A second group of animals was exposed to novel environment stress (NES), and their hippocampal transcriptional profiles measured. A third cohort exposed to control or SD was used to validate transcriptional results with Western blots. Microarray results were statistically contrasted with prior transcriptional studies. Microarray results pointed to sleep pressure signaling and macromolecular synthesis disruptions in the hippocampal CA1 region. Animals exposed to NES recapitulated nearly one third of the SD transcriptional profile. However, the SD -aging relationship was more complex. Compared to aging, SD profiles influenced a significant subset of genes. mRNA associated with neurogenesis and energy pathways showed agreement between aging and SD, while immune, glial, and macromolecular synthesis pathways showed SD profiles that opposed those seen in aging.

Conclusions/Significance

We conclude that although NES and SD exert similar transcriptional changes, selective presynaptic release machinery and Homer1 expression changes are seen in SD. Among other changes, the marked decrease in Homer1 expression with age may represent an important divergence between young and aged brain response to SD. Based on this, it seems reasonable to conclude that therapeutic strategies designed to promote sleep in young subjects may have off-target effects in the aged. Finally, this work identifies presynaptic vesicular release and intercellular adhesion molecular signatures as novel therapeutic targets to counter effects of SD in young subjects.

A closed literature-based discovery technique finds a mechanistic link between hypogonadism and diminished sleep quality in aging men

STUDY OBJECTIVES

Sleep quality commonly diminishes with age, and, further, aging men often exhibit a wider range of sleep pathologies than women. We used a freely available, web-based discovery technique (Semantic MEDLINE) supported by semantic relationships to automatically extract information from MEDLINE titles and abstracts.

DESIGN

We assumed that testosterone is associated with sleep (the A-C relationship in the paradigm) and looked for a mechanism to explain this association (B explanatory link) as a potential or partial mechanism underpinning the etiology of eroded sleep quality in aging men.

MEASUREMENTS AND RESULTS

Review of full-text papers in critical nodes discovered in this manner resulted in the proposal that testosterone enhances sleep by inhibiting cortisol. Using this discovery method, we posit, and could confirm as a novel hypothesis, cortisol as part of a mechanistic link elucidating the observed correlation between decreased testosterone in aging men and diminished sleep quality.

CONCLUSIONS

This approach is publically available and useful not only in this manner but also to generate from the literature alternative explanatory models for observed experimental results.

Sleep disturbances are related to decreased transmission of blue light to the retina caused by lens yellowing

STUDY OBJECTIVES

Sleep pattern and circadian rhythms are regulated via the retinohypothalamic tract in response to stimulation of a subset of retinal ganglion cells, predominantly by blue light (450-490 nm). With age, the transmission of blue light to the retina is reduced because of the aging process of the human lens, and this may impair the photoentrainment of circadian rhythm leading to sleep disorders. The aim of the study was to examine the association between lens aging and sleep disorders.

DESIGN

Cross-sectional population based study.

SETTING

The study was performed at the Research Center for Prevention and Health, Glostrup Hospital, Denmark and at the Department of Ophthalmology, Herlev Hospital, Denmark.

PARTICIPANTS

An age- and sex-stratified sample of 970 persons aged 30 to 60 years of age drawn from a sample randomly selected from the background population.

INTERVENTIONS

Not applicable.

MEASUREMENTS AND RESULTS

Sleep disturbances were evaluated by a combination of questionnaire and the use of prescription sleeping medication. Lens aging (transmission and yellowing) was measured objectively by lens autofluorometry. The risk of sleep disturbances was significantly increased when the transmission of blue light to the retina was low, even after correction for the effect of age and other confounding factors such as smoking habits, diabetes mellitus, gender, and the risk of ischemic heart disease (P < 0.0001).

CONCLUSIONS

Filtration of blue light by the aging lens was significantly associated with an increased risk of sleep disturbances. We propose that this is a result of disturbance of photoentrainment of circadian rhythms.

Persistence of sleep-associated decrease in GnRH pulse frequency in the absence of gonadal steroids

CONTEXT

There is dramatic slowing of GnRH pulse frequency during sleep in the early follicular phase of the menstrual cycle, but it is unknown whether this represents a primary effect of sleep or is dependent upon the sex steroid environment.

OBJECTIVES

Our objective was to determine 1) whether sleep affects GnRH pulse frequency in postmenopausal women (PMW) in whom gonadal hormones are low and 2) whether this relationship changes with aging.

DESIGN AND SETTING

Studies were performed in the Clinical Research Center of an academic medical center.

SUBJECTS

Subjects included healthy PMW, 45-55 (n = 8) and 70-80 (n = 6) years old.

INTERVENTIONS

Subjects were studied during one night of polysomnographic-recorded sleep and one night of monitored wake during which blood was sampled every 5 min for 8 h.

MAIN OUTCOME MEASURES

Pulsatile secretion of free α-subunit (FAS), a marker of GnRH secretion, was assessed.

RESULTS

There were no differences in sleep macroarchitecture or sleep efficiency [75 ± 12% (mean ± sd)] between older and younger PMW. The FAS interpulse interval was longer during sleep than nighttime wake in all women (60.5 ± 4.3 vs. 52.0 ± 2.8 min, P = 0.03) with a similar effect in the two groups. FAS pulse amplitude did not differ between sleep and wake periods (474.8 ± 36.7 vs. 478.2 ± 36.5 ng/liter, P = 0.9).

CONCLUSIONS

Sleep is associated with a significant decline in GnRH pulse frequency in both older and younger PMW. Its persistence in PMW reinforces the important connection between sleep and GnRH secretion.

Deep sleep and parietal cortex gene expression changes are related to cognitive deficits with age

BACKGROUND

Age-related cognitive deficits negatively affect quality of life and can presage serious neurodegenerative disorders. Despite sleep disruption's well-recognized negative influence on cognition, and its prevalence with age, surprisingly few studies have tested sleep's relationship to cognitive aging.

METHODOLOGY

We measured sleep stages in young adult and aged F344 rats during inactive (enhanced sleep) and active (enhanced wake) periods. Animals were behaviorally characterized on the Morris water maze and gene expression profiles of their parietal cortices were taken.

PRINCIPAL FINDINGS

Water maze performance was impaired, and inactive period deep sleep was decreased with age. However, increased deep sleep during the active period was most strongly correlated to maze performance. Transcriptional profiles were strongly associated with behavior and age, and were validated against prior studies. Bioinformatic analysis revealed increased translation and decreased myelin/neuronal pathways.

CONCLUSIONS

The F344 rat appears to serve as a reasonable model for some common sleep architecture and cognitive changes seen with age in humans, including the cognitively disrupting influence of active period deep sleep. Microarray analysis suggests that the processes engaged by this sleep are consistent with its function. Thus, active period deep sleep appears temporally misaligned but mechanistically intact, leading to the following: first, aged brain tissue appears capable of generating the slow waves necessary for deep sleep, albeit at a weaker intensity than in young. Second, this activity, presented during the active period, seems disruptive rather than beneficial to cognition. Third, this active period deep sleep may be a cognitively pathologic attempt to recover age-related loss of inactive period deep sleep. Finally, therapeutic strategies aimed at reducing active period deep sleep (e.g., by promoting active period wakefulness and/or inactive period deep sleep) may be highly relevant to cognitive function in the aging community.

Wake-promoting agent modafinil worsened attentional performance following REM sleep deprivation in a young-adult rat model of 5-choice serial reaction time task

RATIONALE

Individuals who experience sleep loss may exhibit certain physiological abnormalities. Central stimulant drugs have been studied in sleep-loss conditions, and some of them might be therapeutically beneficial. Modafinil (diphenyl-methyl-sulfinyl-2-acetamide, MOD) has been increasingly employed for elevating alertness and vigilance in recent years, yet the underlying mechanism of actions for MOD is not fully understood.

OBJECTIVES

To examine the behavioral effect of MOD following rapid eye movement sleep deprivation (REMD) in rats. A five-choice serial reaction time task (5-CSRTT) was employed to investigate animals' attentional performance and impulsive reactivity.

MATERIALS AND METHODS

Rats of different ages were trained to learn the 5-CSRTT. REMD with the water platform method was applied for 96 h. The impacts of REMD on 5-CSRTT in middle-age (32-weeks-old) and young-adult (12-week-old) rats were compared with baseline or a condition with shorter visual stimulus duration.

RESULTS

The results revealed that following REMD, young-adult but not middle-age rats were liable to be affected in their performances of the 5-CSRTT. In young-adult rats, while MOD had no contributions to the effect of REMD, it worsened rats' performance following REMD when the stimulus duration was shortened, as shown by the reduced number of correct responses and prolonged magazine latency.

CONCLUSIONS

These results suggest that aging might be a crucial factor for the physiological impact following REMD. MOD should be used cautiously, particularly, in conditions that require REM sleep.

Systemic and cellular reflections on ageing and the circadian oscillator: a mini-review

From circulation to digestion to excretion, a circadian clock synchronizes most aspects of mammalian physiology with the solar day. During normal ageing, this daily coordination gradually erodes, and during pathological ageing such erosion is exacerbated. Recent experiments suggest that therapies aimed at sustaining circadian function increase quality of life in elderly patients. Hence, a better understanding of the interactions between the circadian clock and ageing - at both cellular and systemic levels - could lead to direct benefits for aged individuals.

Sleep and metabolism: role of hypothalamic neuronal circuitry

Sleep and metabolism are intertwined physiologically and behaviorally, but the neural systems underlying their coordination are still poorly understood. The hypothalamus is likely to play a major role in the regulation sleep, metabolism, and their interaction. And increasing evidence suggests that hypocretin cells in the lateral hypothalamus may provide particularly important contributions. Here we review: 1) direct interactions between biological arousal and metabolic systems in the hypothalamus, and 2) indirect interactions between these two systems mediated by stress or reward, emphasizing the role of hypocretins. An increased understanding of the mechanisms underlying these interactions may provide novel approaches for the treatment of patients with sleep disorders and obesity, as well as suggest new therapeutic strategies for symptoms of aging, stress, or addiction.

Living alongside railway tracks: Long-term effects of nocturnal noise on sleep and cardiovascular reactivity as a function of age

Very few studies were devoted to permanent effects of nocturnal railway noise on sleep and cardiovascular reactivity. We investigated the effects of nocturnal railway noise on sleep and cardiovascular response in young and middle-aged adults living for many years either near a railway track or in a quiet area. Forty subjects (50% males) divided into two age groups (juniors: 26.2+/-3.6 and seniors: 56.2+/-4.2) participated in this experiment. Half of them lived near a railway track (RW group: 2.6 to 19 years) and the other half in a quiet environment (QE group: 8.1 to 14.2 years). After an adaptation night, all subjects underwent two nights in the laboratory: one control night and one noisy night (30 by-passes of a freight train). Sleep and cardiovascular modifications were assessed in response to noise. Sleep fragmentation indices were lower in RW subjects compared to QE whatever their age. In response to noise, there was a higher cardiovascular response rate to noise in RW juniors and a lower cardiovascular response rate in RW seniors compared to their age-paired QE counterparts. In conclusion, permanent exposure to nocturnal railway noise leads to decreased sleep fragmentation and to cardiovascular habituation. It is suggested that during the initial period experienced by residents living near railway tracks, nocturnal railway noise could induce a sensitization process on the autonomic response to noise reflecting a startle/defense reflex due to its functional significance, which progressively turns to habituation in the long-term if no adverse effect is experienced.

Medication adherence in older renal transplant recipients

This project examined patterns, predictors, and outcomes of medication adherence in a convenience sample of 37 renal transplant recipients aged 55 years or older in a Mid-Southern U.S. facility using an exploratory, descriptive, longitudinal design. Electronic monitoring was conducted for 12 months using the Medication Event Monitoring System. An alarming 86% of the participants were nonadherent with medications. Four clusters of medication taking and timing patterns were identified with evening doses presenting particular challenges. Depression, self-efficacy, social support, and medication side effects did not predict medication adherence. There was no significant difference in medication adherence scores between those with and without infections. Medication adherence pattern data from electronic monitoring provides an opportunity for health care professionals to move away from blaming the patient by attempting to identify predictors for medication nonadherence. Medication dose taking and timing patterns could be explored with patients so that medication adherence interventions could target specific patient patterns.

Sleep in psychiatric disorders: where are we now?

Although the precise function of sleep is unknown, decades of research strongly implicate that sleep has a vital role in central nervous system (CNS) restoration, memory consolidation, and affect regulation. Slow-wave sleep (SWS) and rapid eye movement (REM) sleep have been of significant interest to psychiatrists; SWS because of its putative role in CNS energy recuperation and cognitive function, and REM sleep because of its suggested involvement in memory, mood regulation, and possible emotional adaptation. With the advent of the polysomnogram, researchers are now beginning to understand some of the consequences of disrupted sleep and sleep deprivation in psychiatric disorders. The same neurochemistry that controls the sleep-wake cycle has also been implicated in the pathophysiology of numerous psychiatric disorders. Thus it is no surprise that several psychiatric disorders have prominent sleep symptoms. This review will summarize normal sleep architecture, and then examine sleep abnormalities and comorbid sleep disorders seen in schizophrenia, as well as anxiety, cognitive, and substance abuse disorders.

Aging effects on cardiac and respiratory dynamics in healthy subjects across sleep stages

STUDY OBJECTIVES

Respiratory and heart rate variability exhibit fractal scaling behavior on certain time scales. We studied the short-term and long-term correlation properties of heartbeat and breathing-interval data from disease-free subjects focusing on the age-dependent fractal organization. We also studied differences across sleep stages and night-time wake and investigated quasi-periodic variations associated with cardiac risk.

DESIGN

Full-night polysomnograms were recorded during 2 nights, including electrocardiogram and oronasal airflow.

SETTING

Data were collected in 7 laboratories in 5 European countries.

PARTICIPANTS

180 subjects without health complaints (85 males, 95 females) aged from 20 to 89 years.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

Short-term correlations in heartbeat intervals measured by the detrended fluctuation analysis (DFA) exponent alpha1 show characteristic age dependence with a maximum around 50-60 years disregarding the dependence on sleep and wake states. Long-term correlations measured by alpha2 differ in NREM sleep when compared with REM sleep and wake, besides weak age dependence. Results for respiratory intervals are similar to those for alpha2 of heartbeat intervals. Deceleration capacity (DC) decreases with age; it is lower during REM and deep sleep (compared with light sleep and wake).

CONCLUSION

The age dependence of alpha1 should be considered when using this value for diagnostic purposes in post-infarction patients. Pronounced long-term correlations (larger alpha2) for heartbeat and respiration during REM sleep and wake indicate an enhanced control of higher brain regions, which is absent during NREM sleep. Reduced DC possibly indicates an increased cardiovascular risk with aging and during REM and deep sleep.

Differences in Sleep Complaints in Adults With Varying Levels of Bed Days Residing in Extended Care Facilities for Chronic Disease Management

This cohort study examined differences in perceived insomnia and daytime sleepiness in 67 adults residing in extended care facilities for chronic disease management who had varying levels of bed days. One bed day was defined as spending 24 hours in bed. Planned pairwise comparisons, using Bonferroni adjustment, were made between participants who spent 0 ( n = 21), 2 to 4 ( n = 23), and 5 to 7 ( n = 23) days in bed during 1 week of monitoring. Participants who spent 5 to 7 days in bed had significantly greater insomnia than those who spent 2 to 4 days in bed. No group differences were found in daytime sleepiness. Based on the findings, nurses may assess subjective insomnia and explore sleep hygiene strategies, such as increasing time out of bed with patients who have high levels of 5 to 7 bed days.

Self-reported sleep duration and sleep disturbance are independently associated with cortisol secretion in the Whitehall II study

CONTEXT

The association of short sleep duration with cortisol secretion has not been thoroughly examined in large community dwelling populations and the relative importance of short sleep duration and sleep disturbance is unclear.

OBJECTIVE

The objective of the study was to assess the relationships between self-reported sleep duration, sleep disturbance, and salivary cortisol secretion.

DESIGN

This was a cross-sectional analysis using data from phase 7 (2002-2004) of the Whitehall II study. Sleep disturbances were assessed using a modified version of the Jenkins Scale.

SETTING

The occupational cohort was originally recruited in 1985-1989.

PARTICIPANTS

Analyses included 2751 participants with complete cortisol measures and who collected their first sample within 15 min of waking, were not on medication affecting cortisol secretion, and had complete information for all covariates.

OUTCOME MEASURE

Six saliva samples were taken on waking, waking + 0.5, 2.5, 8, and 12 h and bedtime for the assessment of the cortisol awakening response and the slope in cortisol secretion across the day.

RESULTS

In mutually adjusted analyses, both sleep duration and disturbances were independently associated with a flatter diurnal slope in cortisol secretion, such that evening cortisol secretion was raised in those reporting short sleep duration and high sleep disturbance. Short sleep duration was also associated with the cortisol awakening response. These effects were independent of a number of covariates, including waking time on day of sampling and stress on the day of cortisol assessment.

CONCLUSION

Short sleep duration and increased sleep disturbances are independently associated with diurnal slope in cortisol secretion of a large community-based cohort of middle-aged men and women.

The wake-promoting effects of hypocretin-1 are attenuated in old rats

Disruption of sleep is a frequent complaint among elderly humans and is also evident in aged laboratory rodents. The neurobiological bases of age-related sleep/wake disruption are unknown. Given the critical role of the hypocretins in sleep/wake regulation, we sought to determine whether the wake-promoting effect of hypocretin changes with age in Wistar rats, a strain in which age-related changes in both sleep and hypocretin signaling have been reported. Intracerebroventricular infusions of hypocretin-1 (10 and 30 μg) significantly increased wake time relative to vehicle in both young (3 mos) and old (25 mos) Wistar rats. However, the magnitude and duration of the wake-promoting effects were attenuated with age. An increase of parameters associated with homeostatic sleep recovery after sleep deprivation, including non-rapid eye movement (NR) sleep time, NR delta power, the ratio of NR to rapid eye movement (REM) sleep, and NR consolidation, occurred subsequent to Hcrt-induced waking in young but not old rats. ICV infusions of hypocretin-2 (10 and 30 μg) produced fewer effects in both young and old rats. These data demonstrate that activation of a major sleep/wake regulatory pathway is attenuated in old rats.

Sleep disturbances in older adults with mild cognitive impairment

BACKGROUND

Normal aging and dementia are characterized by increased prevalence of sleep disorders and alterations of both sleep continuity and architecture. However, little is still known about the nature of sleep in mild cognitive impairment (MCI), which is presumably situated on the continuum from healthy aging to dementia. This unsystematic review summarizes the current literature on the prevalence and severity of sleep disturbances in MCI.

METHODS

Eighteen studies addressing sleep/night-time disturbances among other neuropsychiatric symptoms in individuals with MCI were identified through a search of databases and an examination of reference lists of selected papers. Fifteen of those studies reported data on prevalence or severity of sleep/night-time disturbances.

RESULTS

Results indicated that 14-59% of patients with MCI had sleep disturbances. These disturbances were often identified as one of the four most prevalent neuropsychiatric symptoms of MCI and were considered as clinically significant in some studies. In addition, there was some evidence that the prevalence of sleep disturbances in MCI is intermediate between that of normal aging and dementia. Longitudinal data suggest that sleep problems are associated with both incident MCI and dementia.

CONCLUSIONS

These findings support the hypothesis that sleep disturbances are one of the core non-cognitive symptoms of MCI. It remains to be known whether sleep problems could help to identify those individuals with MCI who will eventually develop dementia. Studies characterizing sleep more systematically are needed to verify this proposition and to clarify the associations between sleep disturbances and other neuropsychiatric symptoms of MCI.

Fat circadian biology

While adipose tissue has long been recognized for its major role in metabolism, it is now appreciated as an endocrine organ. A growing body of literature has emerged that identifies circadian mechanisms as a critical regulator of adipose tissue differentiation, metabolism, and adipokine secretory function in both health and disease. This concise review focuses on recent data from murine and human models that highlights the interplay between the core circadian regulatory proteins and adipose tissue in the context of energy, fat, and glucose metabolism. It will be important to integrate circadian mechanisms and networks into future descriptions of adipose tissue physiology.

Sleep quality in women with and without postpartum depression

OBJECTIVE

To compare and measure the effects of sleep quality in women with and without postpartum depression.

DESIGN

A case-control repeated measures matched pairs design.

SETTING

Home and obstetric office.

PARTICIPANTS

Forty-six women who were 6 to 26 weeks postpartum. Two participants were dropped from the final analysis because they were outliers.

METHODS

Participants underwent wrist actigraphy at home for 7 consecutive days to measure sleep quality. The Postpartum Depression Screening Scale measured depression severity. Psychosocial variables were collected during a screening interview. A structured clinical interview was used to diagnose postpartum depression. Correlations, t tests, and hierarchical multiple regressions were run to analyze data.

RESULTS

With the exception of wake episodes, sleep latency (B=1.80, SE=0.73, p<.05), wake after sleep onset (B=6.85, SE=2.85, p<.05), and thus sleep efficiency (B=-6.31, SE=3.13, p<.05) predicted postpartum depression symptom severity.

CONCLUSIONS

Women with postpartum depression experienced poorer sleep quality than women without postpartum depression, and sleep quality worsened with increasing postpartum depression symptom severity. Clinicians need to address measures to improve sleep quality in depressed mothers to decrease symptom severity, and researchers need to develop interventions to facilitate better sleep quality in women with postpartum depression.