Donald L. Bliwise

Prevalence of self-reported poor sleep in a healthy population aged 50-65

Many population-based surveys have reported that the prevalence of poor sleep increases with age. Despite the uniformity of findings, it remains unclear to what extent age-related declines in overall physical health are related to those results. One approach to this problem has been to adjust for such confounding variables multivariately. Some prior studies using this approach have not shown the expected age-related increases in the prevalence of poor sleep. Another approach has been the study of sleep in carefully screened, healthy populations. The current study reports the prevalence of disturbed sleep in a population, ages 50-65, carefully screened for physical health as part of an ongoing study of exercise and cardiovascular function. The prevalence of self-reported trouble falling asleep every night or almost every night (1.1% M, 2.6% F), trouble awakening and returning back to sleep (4.4% M, 3.3% F), and use of hypnotic medication at least twice a week (1.6% M, 2.6% F) were consistently lower than in nearly all previous population-based studies of individuals of comparable age. This implies that when overall physical health factors are taken into account a decline in sleep quality is not necessarily an inevitable component of aging per se. As has been shown in other studies, there were small but statistically significant relationships between self-reported depression and poor sleep. Despite the low prevalence of poor sleep, about a third of the population reported feeling not well-rested and/or not getting the sleep they required. The individuals in this study also reported obtaining significantly less sleep relative to normative data from 30 years ago.(ABSTRACT TRUNCATED AT 250 WORDS)

REM latency in Alzheimer's disease

Latency to the first episode of rapid eye movement sleep (REML) has been proposed as a potential biomarker for Alzheimers disease (AD). In this study, we compared REML values from 28 AD patients and 28 age- and sex-matched controls. We employed multiple definitions of REML and multiple cutoffs to classify patients and controls. Results indicated that the best REML definition and optimal cutoff criterion resulted in only 65% correct classifications. We discuss the longer REML in AD patients relative to controls in terms of both overall sleep disturbance and selective deterioration of the REM-cholinergic system. As REML may be relatively short in other forms of psychopathology (e.g., affective disorders), REML may still hold promise in the differential diagnosis of dementia and pseudodementia.

Nightly variation of periodic leg movements in sleep in middle aged and elderly individuals

This study investigated night-to-night variation in periodic leg movements in sleep (PLMS). PLMS are common in the elderly, but their mechanism and significance are not understood. Forty-five aged individuals (means = 69.7 years) were studied polysomnographically for 2 or 3 nights with surface electrodes placed above the anterior tibialis. Results indicated that PLMS varied considerably from night to night within individuals, though there was not a significant difference between nights for the entire group. Some evidence indicated that individuals with less severe sleep complaints showed greater nightly variation. The nightly variation in PLMS was over four times as large as the nightly variation in breathing disturbance in sleep, another condition common in the sleep of the aged. These data suggest that studies relating PLMS to other key variables (e.g. symptoms of disturbed sleep) should rely on multiple nights of data or, if single night data are used, be particularly careful to replicate findings across samples.

Habitual sleep durations and health in a 50–65 year old population

Several studies have suggested that individuals with long or short sleep durations are at greater risk for adverse outcomes relative to individuals sleeping 7-8 hours a night. The mechanisms leading to these results have never been fully explained, but individual differences in how long an individual sleeps are usually considered to reflect lifestyle rather than disease. Alternatively, individuals may sleep a particular amount because of characteristics of their sleep physiology. In this study, we examined population-based data on the associations between sleep duration and several symptoms of sleep-related disease, reported snoring and daytime sleepiness. Results from 1877 independently living individuals between the ages of 50 and 65 years suggested that long, but not short, sleep durations were related to greater reported snoring. Higher levels of reported snoring and daytime sleepiness, but not habitual sleep duration, were related to measures of disease and lower psychosocial function. We suggest that future epidemiologic studies use such additional items as potential indicators of sleep-related disease.

Sleep apnea in Alzheimer's disease

Mental deterioration accompanying sleep apnea has been noted frequently. Because sleep apnea increases with age, such deficits raise the possibility that dementia in the elderly could be related to sleep apnea. In this study we investigated this possibility cross-sectionally by comparing respiration during sleep in 28 patients with Alzheimers disease (AD) and 25 nondemented controls. We hypothesized that higher levels of sleep apnea would be present in AD patients. Our results indicated no significant differences between AD patients and controls but those few AD patients who desaturated during sleep experienced morning confusion. The findings imply that AD and sleep apnea are two separate conditions which may still interact in the aged.

Systematic 24-hr behavioral observations of sleep and wakefulness in a skilled-care nursing facility.

Sleep patterns of aged, infirm, demented, chronically institutionalized residents of a skilled-care nursing facility were studied. The purpose of this naturalistic study was to describe sleep and wakefulness (S/W) within the limits afforded by brief behavioral observations and to examine homeostasis and diurnal rhythmicity of S/W as a function of psychoactive drug intake. Observers noted S/W every 15 min, 24 hr a day for 10 days in 24 Ss. Results indicated substantial individual variation in daytime hours. Daily and weekly variation within Ss was minimal. Sleep was least likely near sunset. Ss on psychoactive drugs showed dampened diurnal variation in S/W rhythms. In Ss not on such drugs, there was a suggestion of homeostasis of S/W between sleep during the morning and evening hours. Results are discussed methodologically (viability of approach), theoretically (age-related change in sleep), and practically (potential treatments).

Prediction of outcome in behaviorally based insomnia treatments

Factors related to successful behavioral intervention for individuals with insomnia are not well understood. In this study we employed the Neuroticism, Extraversion and Openness (NEO) Personality Inventory, to predict successful treatment outcome. Two behavioral treatments for insomnia, sleep restriction therapy (SRT) and relaxation training (RT) were employed in 32 elderly insomniacs. Following two baseline weeks, subjects underwent four weeks of individual treatment. Daily telephone call-ins generated data on sleep times and sleep latency. Follow-up occurred three months after the end of treatment. Results indicated that subjects showing the greatest improvement in total sleep time with both treatments were more traditional, conventional and rigid. Improvement in sleep onset latency was unrelated to NEO Scores. SRT appeared to be more effective for increasing total sleep time in these older subjects.

Periodic leg movements during sleep in the elderly

Periodic leg movements in sleep (PLMS) occur frequently in the sleep of elderly persons but their significance is unknown. In this study, 63 elderly persons with symptoms of insomnia but without history of renal disease were evaluated polysomnographically. All received laboratory evaluations for blood urea nitrogen (BUN) and creatinine and completed a questionnaire on sleep complaints. Results indicated a positive relationship between PLMS and urea nitrogen in elderly women. In addition, symptoms of leg twitching and prolonged sleep latency could distinguish arbitrarily formed high and low PLMS groups. These results suggest that PLMS could be a window on the age-related decline in renal function and that these movements are related to several highly specific symptoms of geriatric insomnia.

MSLT-defined sleepiness and neuropsychological test performance do not correlate in the elderly

This study investigated whether a sensitive, physiological measure of alertness/sleepiness, the Multiple Sleep Latency Test (MSLT), was related to neuropsychological test performance in elderly individuals. We hypothesized that the greater likelihood of falling asleep during the daytime on the MSLT would be related to relatively poorer performances on a variety of neuropsychological tests. Results from a homogeneous sample of 35 relatively well-educated, high functioning, elderly community volunteers confirmed the presence of characteristic levels of daytime alertness which were stable within individuals (r = .70 to .73) and showed large variation across individuals (coefficients of variation: 54-84%). Despite this wide intersubject variability, MSLT-defined alertness/sleepiness was unrelated to neuropsychological test results. We discuss these results in terms of the performance deficits known to accompany sleepiness in experimental studies of sleep deprivation and in terms of the behavioral slowing known to occur in normal aging.

Sleep disturbance produced by electrical stimulation of the locus coeruleus in a human subject.

A 25-year-old man with a chronically implanted stimulating electrode placed in the region of the locus coeruleus (LC) was monitored for 5 nights in a sleep laboratory to study the role of the LC in sleep. Sleep patterns were compared between the 2 nights in which the stimulation was applied periodically every 90 min and the 2 nights in which no stimulation was applied. In contrast to the normal sleep patterns that occurred during the 2 nonstimulation nights, electrical stimulation of the LC produced a profound disruption of sleep and significant reductions in the total amounts of NREM sleep, REM sleep, REM sleep as a percent of total sleep (NREM + REM sleep), and total sleep. Results suggest that the LC has a role in maintaining normal sleep patterns.