Circadian abnormalities in older adults.

This study examined the circadian phase adjustment of symptomatic elders ages 60-79 years in comparison with that of young, healthy adults ages 20-40 years. Seventy-two elders with complaints of insomnia or depression, and 30 young, healthy adults were assessed for 5-7 days at home. Sleep and illumination were recorded with Actillume wrist monitors and sleep diaries. Urine was collected over two 24-hr periods and assayed for 6-sulphatoxymelatonin (6-smt). The volunteers were then observed continuously for 5 nights and 4 days in the laboratory. In the laboratory, sleep periods were fixed at 8 hr with polysomnographic assessment of sleep, apnea-hypopnea, and nocturnal myoclonus. Circadian dispersion, defined as the mean variation of 6-smt acrophase from the median age-specific acrophase, was significantly greater in the older vs. young adults. Likewise, circadian malsynchronization, defined as the absolute number of hours (advance or delay) between the 6-smt acrophase and the middle of the sleep period, was significantly greater in the older vs. young volunteers. For the older volunteers, multiple regressions were calculated associating sleep with potential correlates of sleep disturbance. Nocturnal myoclonus and circadian malsynchronization were more strongly associated with sleep impairment than other factors (e.g., sleep apnea, depression). These observations suggest that circadian malsynchronization might be a common and significant cause of disturbed sleep among adults over age 60.

Short version of the CES-D (Burnam screen) for depression in reference to the structured psychiatric interview.

A new screen for depression was compared with clinician diagnoses based on the Structured Clinical Interview for DSM-IV (SCID) as the standard. Post-menopausal women (n=436) completed the Burnam screen, a short version of the Center for Epidemiologic Studies Depression Scale (CES-D). The Burnam screen had a sensitivity of 74% and a specificity of 87% for current major depression and dysthymia, but the positive predictive value was low (20%) and the overall error rate was 14%. For lifetime mood disorders, sensitivity was very low for detecting affected subjects, even though specificity and positive predictive value were higher than for current conditions. Substituting a more sensitive cutpoint slightly improved the screen's ability to detect subjects with lifetime mood disorders. Even algorithms that used coefficients optimized for these data gave little improvement in the psychometric properties of the Burnam screen. These results re-emphasize the difficulty of using a one-stage screen to detect accurately a depressive diagnosis.

Sleep duration, illumination, and activity patterns in a population sample: effects of gender and ethnicity.

BACKGROUND: Current knowledge of the population's sleep durations emanates primarily from questionnaires and laboratory studies. Using Actillumes, we investigated whether self-reported sleep durations were indicative of a population decline in sleep duration. We also explored illumination and activity patterns. METHODS: San Diego adults (n = 273, age range: 40-64) were recruited through random telephone calls and were monitored at home while engaging in usual daily routines. RESULTS: Volunteers slept an average of 6.22 hours and received an average of 554 lux (environmental illumination). The timing of sleep, illumination, and activity occurred at 2:44, 12:57, and 13:43, respectively. Irrespective of ethnicity, age, and time reference, men received greater illumination than did women, but this gender effect was not independent of work status. Women and men exhibited a similar circadian activity profile; however, women exhibited better sleep-wake patterns. Interactions between gender and ethnicity suggested worse sleep-wake patterns among minority men. An age-related decline in activity was found, but no age trend in sleep duration or illumination patterns was observed. CONCLUSIONS: This study showed an objective population decline in sleep duration. Sociodemographic effects should be considered in analyses of sleep-wake patterns and illumination exposures.

Circadian sleep, illumination, and activity patterns in women: influences of aging and time reference.

Patterns of sleep, illumination, and activity of women of different ages were continuously monitored in their natural environments with a wrist activity monitor. Partial correlation analyses were performed to determine relationships between age and sleep and several circadian rhythm measures including the amplitudes, mesors, and timings of sleep, of illumination, and of activity. We found no age-related decline in actigraphic sleep duration. Age was not a significant correlate of circadian rhythm parameters of sleep. Moreover, no age effects were found on daily illumination exposure or on the circadian timing of illumination and activity patterns. However, the level and amplitude of the circadian activity rhythm showed a gradual decline with aging, independent of the time reference (i.e., Daylight Saving Time versus Standard Time) when recordings were obtained. As expected, significant associations were observed between local time reference and the level and timing of peak of illumination patterns. However, changes in local time reference were not significantly and consistently associated with actigraphic sleep or activity measures.

The correlation between the severity of peripheral arterial disease and carotid occlusive disease.

Peripheral arterial disease (PAD) and carotid occlusive disease (COD) are both known to be specific manifestations of atherosclerosis. Because they both have a common cause, it is reasonable to hypothesize that they should correlate with each other to a certain extent, and previous studies have shown that there is a correlation between the prevalence of PAD and COD. The purpose of this study was to determine whether a correlation exists between the severity of PAD and the severity of COD by retrospectively looking at a group of 203 patients who underwent non-invasive testing for suspicion of PAD at the San Diego VA Hospital or UCSD Medical Center, and who also had a non-invasive duplex carotid scan. The severity of PAD was assessed by segmental blood pressure ratios (leg segment/arm ratio) in each leg taken at the toe, ankle, and below the knee, as well as the peak flow velocity of the posterior tibial artery. The severity of COD was assessed by duplex ultrasound scans of six distinct segments of the carotid artery system: the right and left common, internal, and external carotid arteries. Correlation analysis showed r=0.23 (p=0.001) when comparing a PAD aggregate standard score with the number of diseased carotid arteries (>50% stenosis), and r=0.23 (p=0.001) when comparing a PAD aggregate standard score with an average COD score. Because about 50% of the patients had undergone surgical intervention on their leg or carotid arteries, another correlation analysis restricted to patients with no surgical interventions (n = 97) was performed. The above correlations were slightly attenuated in this analysis, r=0.21 (p=0.043) and r=0.17 (p= 0.092), respectively. The results indicate that there is a modest but significant correlation between the severity of PAD and the severity of COD in a population with a high prevalence of both.

Quantitative and qualitative progression of peripheral arterial disease by non-invasive testing.

There is little information on the progression of peripheral arterial disease (PAD) over time. A series of 508 patients with a prior examination for PAD were contacted and brought in for follow-up to evaluate the natural history of PAD. A total of 85 patients were excluded because they had interventions in both limbs prior to their return visit. Progression was assessed in the remaining 423 patients for a total of 755 limbs, both quantitatively and qualitatively using six categories of PAD severity. There was a modest overall categorical progression of disease: 228 limbs (30.2%) displayed categorical progression, while 172 limbs (22.8%) improved over a 4.6-year average follow-up. Through analysis of quantitative change, it was determined that more quantitative progression occurred than was evident from categorical progression. Two of the three non-invasive tests employed, the ankle/brachial index (ABI) and posterior tibial peak forward flow velocity (peak PT), showed statistically significant progression during follow-up: mean ABI change = -0.019, 95% confidence interval (CI)= -0.031 to -0.007; mean peak PT change = -2.32 cm/s, 95% CI = -3.20 to -1.44. The toe/brachial index (TBI) also suggested progression: mean change= -0.013, but the 95% CI included no change. Standard scores (sum of the Z-scores for ABI, peak PT and TBI) were calculated. The standard score progressed approximately 0.34 units (standard deviations), p-value <0.001, over 4.6 years; or about 0.07 standard deviations per year. There were independent and statistically significant (p<0.05) associations between the rate of PAD progression (standard score change) and age, diabetes, classic ('Rose') intermittent claudication, moderate to severe PAD in the same limb, moderate to severe PAD in the contralateral limb and future therapeutic intervention. There were independent and suggestive associations (0.05

Hourly profiles of sleep and wakefulness in severely versus mild-moderately demented nursing home patients.

The purpose of the current study was to examine differences in hour-by-hour sleep/wakefulness profiles between severely and mild-moderately demented patients, and to assess how many elderly patients remain almost fully asleep or nearly fully awake in each hour of a 24-hour period. Sleep/wakefulness patterns of 67 demented nursing home residents (mean age = 85.7 years) were recorded using Actillume recorders. One 24-hour period was used, and numbers of minutes spent asleep or awake were computed for every hour. There were 46 severely demented patients, and 21 mild-moderately demented patients. The amount of sleep and wakefulness recorded for each hour was compared between the two groups. In addition, the frequencies of patients who remained asleep for more than 90% of each hour, and of those who sustained wakefulness for more than 90% of each hour were computed for every hour, and comparisons were again made between the two groups. Multivariate analysis of variance showed a significant effect of dementia group on the percent of sleep/wakefulness over 24 hours (p = 0.028). Subsequent t-tests performed separately for each hour revealed significant differences between the two dementia groups in 13 out of the 24 hours. Significant differences in the frequencies of patients asleep > 90% or awake > 90% of each hour were centered around the early night and early morning hours. Patients with mild-moderate dementia showed a disproportionate amount of wakefulness during the night, whereas, in addition, patients with severe dementia showed a disproportionate amount of sleepiness during the day. With the progression of dementia, both the capacity to maintain sleep and the capacity to maintain wakefulness are impaired, and result in complete fragmentation of sleep/wakefulness during the night and day.

Periodic leg movements during sleep and sleep disturbances in elders.

BACKGROUND: Periodic limb movements in sleep (PLMS) are an increasingly pervasive disturbance for aging adults. The aims of this experiment were: (a) to describe the index of periodic limb movements in sleep (myoclonus index [MI] in elderly subjects with complaints of poor sleep or depression (N = 22; 68 +/- 5.5 SD years); and (b) to correlate MI with sleep history, depression scores, and objective and subjective indices of sleep. METHOD: Sleep and leg movements were assessed for 5 consecutive nights. Between-subjects, nonparametric correlations were examined between mean MI and sleep history, depression scores, and objective and subjective sleep characteristics. Associations among within-subject night-to-night variabilities of MI, objective, and subjective variables were examined with repeated measures ANCOVA, entering MI as a covariate. RESULTS: A remarkably high level of MI was found (median 25.8 events per hour; 86% of subjects > 5). Nevertheless, no associations were found between MI and sleep disturbance measures. CONCLUSION: These results extend previous reports that PLMS are remarkably persuasive in elderly volunteers and support other reports questioning whether there is a distinct PLMS syndrome.

A multicenter trial on the efficacy of using tirilazad mesylate in cases of head injury.

OBJECT: The authors prospectively studied the efficacy of tirilazad mesylate, a novel aminosteroid, in humans with head injuries. METHODS: A cohort of 1120 head-injured patients received at least one dose of study medication (tirilazad or placebo). Eighty-five percent (957) of the patients had suffered a severe head injury (Glasgow Coma Scale [GCS] score 4-8) and 15% (163) had sustained a moderate head injury (GCS score 9-12). Six-month outcomes for the tirilazad- and placebo-treated groups for the Glasgow Outcome Scale categories of both good recovery and death showed no significant difference (good recovery in the tirilazad-treated group was 39% compared with the placebo group in which it was 42% [p=0.461]; death in the tirilazad-treated group occurred in 26% of patients compared with the placebo group, in which it occurred in 25% [p=0.750]). Subgroup analysis suggested that tirilazad mesylate may be effective in reducing mortality rates in males suffering from severe head injury with accompanying traumatic subarachnoid hemorrhage (death in the tirilazad-treated group occurred in 34% of patients; in the placebo group it occurred in 43% [p=0.026]). No significant differences in frequency or types of serious adverse events were shown between the treatment and placebo groups. CONCLUSIONS: Striking problems with imbalance concerning basic prognostic variables were observed in spite of the large population studied. These imbalances concerned pretreatment hypotension, pretreatment hypoxia, and the incidence of epidural hematomas. In future trials of pharmacological therapy for severe head injury, serious consideration must be given to alternative randomization strategies. Given the heterogeneous nature of head injury and the identification of populations that do relatively well with standard therapy, target populations with a higher risk for mortality and morbidity may be more suitable for clinical trials of such agents.

Neurogenic hypotension in patients with severe head injuries.

OBJECTIVE: To examine the occurrence of hypotensive episodes in patients with severe traumatic brain injuries that are not of hypovolemic origin and to investigate possible neurogenic or iatrogenic causes of such episodes. METHODS: We reviewed Traumatic Coma Data Bank (TCDB) records of the 248 patients with early hypotension. We attempted to eliminate episodes related to hemorrhagic hypovolemia by excluding patients with (1) extracranial injuries of Abbreviated Injury Scale scores > 3 (n = 99, 40%); (2) postresuscitation hematocrit levels < 35% (n = 76, 30.6%); (3) hematocrit levels decreasing to < 35% during the first 24 hours after injury (n = 47, 19%); and (4) patients with conflicting data (n = 5, 2%). This left 21 patients (8.5%) without discernible extracranial causes for their hypotension. RESULTS: Of these 21 patients, 4 had no extracranial injuries and 4 had only a single injury with Abbreviated Injury Scale score = 1. Hypotensive episodes were not associated with terminal or unsalvageable status. Mortality was 43%. Of the multiple factors investigated, the only two that were strongly associated with these "unexplained" hypotensive episodes were the presence of a diffuse injury pattern on computed tomography (n = 15, 71%) and the early use of mannitol or furosemide (n = 16, 76%) (It was policy at TCDB centers that hypotensive patients not receive diuretics until they were resuscitated.) CONCLUSIONS: (1) Some episodes of severe traumatic brain injury-related hypotension may be of neurogenic origin. (2) The risk/benefit ratio of early diuretic use in patients with severe traumatic brain injuries may be too high to support liberal use. These data strongly support the need for a study involving prospective collection of data describing the early blood pressure courses in such patients.

Mortality hazard associated with prescription hypnotics.

BACKGROUND: The American Cancer Society's Cancer Prevention Study II was a large survey designed primarily to examine cancer risks such as cigarette smoking. From the same survey and methods, data on usage of "prescription sleeping pills" in 1982 were examined. METHODS: Standardized mortality ratios were computed. Because sleeping pill use could be a proxy for other risk factors, cox proportional hazards models were computed to control for possible confounding factors as extensively as the data permitted. RESULTS: Men and women who reported taking prescription sleeping pills 30+ times in the past month had standardized mortality ratios of 3.18 and 2.82, respectively; controlling for 10-year age groups (p < 0.001). The standardized mortality ratios for usage 1-29 times/month were 1.8 and 1.48, respectively (p < 0.001). In proportional hazards models that controlled for 30 other risk factors and comorbidities simultaneously, the excess mortality risk associated with usage 30+ times per month remained significant, but hazard ratios were reduced to 1.35 for men and 1.22 for women. CONCLUSIONS: Use of hypnotics was associated with excess mortality. This methodology could not determine if hypnotic compounds caused the risks associated with their use, nor could the risks of individual compounds be determined. Since millions of Americans are currently taking hypnotics, long-term controlled trials are urgently needed to further guide both patients and physicians.

Blunted phase-shift responses to morning bright light in premenstrual dysphoric disorder.

Patients with premenstrual dysphoric disorder (PMDD) respond therapeutically to sleep deprivation and light therapy. They have blunted circadian rhythms of melatonin. The authors sought to test the hypothesis that these disturbances are a reflection of a disturbance in the underlying circadian pacemaker or, alternatively, that they reflect a disturbance in the input pathways to the clock. To test these hypotheses, after a 2-month diagnostic evaluation, 8 patients who met DSM-IV criteria for PMDD and 5 normal control (NC) subjects underwent two studies to determine whether PMDD subjects showed (1) altered melatonin sensitivity to light suppression (Study 1) and (2) altered phase-shift responses to morning light as a measure of the functional capacity of the underlying pacemaker (Study 2). In both studies, measurements were made during asymptomatic follicular and symptomatic luteal menstrual cycle phases in PMDD patients. The results of Study 1 showed no significant effect of group or menstrual cycle phase on the amount or percentage of suppression of melatonin by light. The results of Study 2 showed that with respect to the variable of offset time, PMDD subjects, when symptomatic, showed a reduced and directionally altered melatonin phase-shift response to a morning bright light stimulus; in 4 of 5 NC subjects, melatonin offset was advanced by bright morning light, whereas in PMDD subjects, it was delayed (3 subjects) or not shifted (5 subjects) (group effect, p = .045). Study 2 also revealed that area under the curve also changed differentially in PMDD versus NC subjects. In summary, the primary findings from this pilot study suggest that in PMDD there is a maladaptive (directionally altered and blunted) response to light in the symptomatic luteal phase. Because the suppressive effects of light were similar in PMDD and NC subjects, the previously observed low melatonin levels in this disorder do not likely represent a disturbance in pineal reactivity to suprachiasmatic nucleus efferents. Instead, the findings support a possible disturbance in PMDD in the clock itself or its coupling mechanisms.

A controlled trial of selegiline, alpha-tocopherol, or both as treatment for Alzheimer's disease. The Alzheimer's Disease Cooperative Study.

BACKGROUND: There is evidence that medications or vitamins that increase the levels of brain catecholamines and protect against oxidative damage may reduce the neuronal damage and slow the progression of Alzheimer's disease. METHODS: We conducted a double-blind, placebo-controlled, randomized, multicenter trial in patients with Alzheimer's disease of moderate severity. A total of 341 patients received the selective monoamine oxidase inhibitor selegiline (10 mg a day), alpha-tocopherol (vitamin E, 2000 IU a day), both selegiline and alpha-tocopherol, or placebo for two years. The primary outcome was the time to the occurrence of any of the following: death, institutionalization, loss of the ability to perform basic activities of daily living, or severe dementia (defined as a Clinical Dementia Rating of 3). RESULTS: Despite random assignment, the baseline score on the Mini-Mental State Examination was higher in the placebo group than in the other three groups, and this variable was highly predictive of the primary outcome (P<0.001). In the unadjusted analyses, there was no statistically significant difference in the outcomes among the four groups. In analyses that included the base-line score on the Mini-Mental State Examination as a covariate, there were significant delays in the time to the primary outcome for the patients treated with selegiline (median time, 655 days; P=0.012), alpha-tocopherol (670 days, P=0.001) or combination therapy (585 days, P=0.049), as compared with the placebo group (440 days). CONCLUSIONS: In patients with moderately severe impairment from Alzheimer's disease, treatment with selegiline or alpha-tocopherol slows the progression of disease.

Plasma melatonin circadian rhythms during the menstrual cycle and after light therapy in premenstrual dysphoric disorder and normal control subjects.

The aim of this study was to replicate and extend previous work in which the authors observed lower, shorter, and advanced nocturnal melatonin secretion patterns in premenstrually depressed patients compared to those in healthy control women. The authors also sought to test the hypothesis that the therapeutic effect of bright light in patients was associated with corrective effects on the phase, duration, and amplitude of melatonin rhythms. In 21 subjects with premenstrual dysphoric disorder (PMDD) and 11 normal control (NC) subjects, the authors measured the circadian profile of melatonin during follicular and luteal menstrual cycle phases and after 1 week of light therapy administered daily, in a randomized crossover design. During three separate luteal phases, the treatments were either (1) bright (> 2,500 lux) white morning (AM; 06:30 to 08:30 h), (2) bright white evening (PM; 19:00 to 21:00 h), or (3) dim (< 10 lux) red evening light (RED). In PMDD subjects, during the luteal phase compared to the follicular menstrual cycle phase, melatonin onset time was delayed, duration was compressed, and area under the curve, amplitude, and mean levels were decreased. In NC subjects, melatonin rhythms did not change significantly during the menstrual cycle. After AM light in PMDD subjects, onset and offset times were advanced and both duration and midpoint concentration were decreased as compared to RED light. After PM light in PMDD subjects, onset and offset times were delayed, midpoint concentration was increased, and duration was decreased as compared to RED light. By contrast, after light therapy in NC subjects, duration did not change; onset, offset, and midpoint concentration changed as they did in PMDD subjects. When the magnitude of advance and delay phase shifts in onset versus offset time with AM, PM, or RED light were compared, the authors found that in PMDD subjects light shifted offset time more than onset time and that AM light had a greater effect on shifting melatonin offset time (measured the following night in RED light), whereas PM light had a greater effect in shifting melatonin onset time. These findings replicate the authors' previous observation that nocturnal melatonin concentrations are decreased in women with PMDD and suggest specific effects of light therapy on melatonin circadian rhythms that are associated with mood changes in patient versus control groups. The differential changes in onset and offset times during the menstrual cycle, and in response to AM and PM bright light compared with RED light, support a two-oscillator (complex) model of melatonin regulation in humans.

Variations in circadian rhythms of activity, sleep, and light exposure related to dementia in nursing-home patients.

We measured 24-hour circadian-rhythm patterns of activity and sleep/wake activity in a group of nursing-home patients (58 women and 19 men with a mean age of 85.7 years). Severely demented patients were contrasted with a composite group of moderate y, mild, or not-demented patients. Sleep/wake activity and light exposure were recorded with the Actillume recorder. Cosinor analyses were computed to determine the mesor, amplitude, acrophase, and circadian quotient of the activity rhythms. The diagnosis of dementia was based on the Mini Mental Examination and on examination of medical records. Sleep was extremely fragmented in both groups of nursing-home patients. Severely demented patients slept more both at night and during the day, but there were no significant differences in the number of awakenings during the night or in the number of naps during the day when compared to the composite group of moderate, mild, or no-dementia patients. The severely demented group had lower activity mesor, more blunted amplitude, and were more phase delayed (i.e. had later acrophases) than the other group. In addition, the severely demented patients spent less time exposed to bright light. These results confirm that circadian rhythms in nursing-home patients are disturbed with more disturbance in the severely demented. Much of the disturbance may be related not just to age but to mental status.

Use of wrist activity for monitoring sleep/wake in demented nursing-home patients.

Actigraphy is applicable for studying sleep in populations who are unable to tolerate traditional sleep-recording techniques, such as nursing-home patients who are infirm and demented. This study examined whether actigraphy can accurately reflect sleep/wake activity in this population by testing the reliability of a wrist-activity monitor, the Actillume, against traditional sleep measurements and against observations of nursing-home patients. Data from the Actillume are presented as two variables, the sum (total of all activity movements within the prescribed epoch) and the maximum activity (the largest or maximum movement recorded during the prescribed epoch), and by electroencephalogram (EEG). One difficulty in making comparisons was that the EEG records showed diffuse slowing, making it extremely difficult to score sleep/wake activity and making it difficult to use the EEG as a "gold standard". Nevertheless, the correlation for total sleep time from EEG and Actillume was r = 0.91 (p < 0.001) for sum activity and r = 0.81 for maximum activity (p < 0.005). Correlations for percent sleep were r = 0.78 (p < 0.01) for maximum activity and r = 0.61 for sum activity. The comparison of sleep/wake determined by the Actillume vs. observations resulted in a sensitivity of 87% and specificity of 90%. We conclude that the Actillume is the most feasible technique for studying sleep and wake activity in demented nursing-home patients.

Prevalence of sleep-disordered breathing in ages 40-64 years: a population-based survey.

Previous research has offered widely varying prevalence estimates for sleep apnea in the population, leaving uncertain which breathing patterns are abnormal. To explore the distribution of sleep apnea in the population and its co-morbidities, random telephone dialing was used between 1990 and 1994 to recruit subjects for a prevalence survey of sleep-disordered breathing in San Diego adults. Events from which blood oxygen desaturations > or = 4% resulted were monitored with home recording instruments, usually for three consecutive nights. Among 190 women ages 40-64 years, a median of 4.3 desaturation events per hour of sleep were observed. A higher median of 6.7 events per hour was observed among 165 men. Frequencies were much higher among members of minority groups, leading to a standard estimate that 16.3% of U.S. Hispanics and racial minorities have > or = 20 events/hour as compared to 4.9% of non-Hispanic Whites ages 40-64. Obesity indicated by body-mass index was the most important demographic predictor of sleep-disordered breathing, followed by age, male gender, and ethnicity. Quality of well-being was not significantly impaired in subjects with more respiratory events; however, there was some increase in blood pressure and wake-within-sleep associated with sleep-disordered breathing. This survey indicates that sleep-disordered breathing is more common, especially among minorities, than had been previously believed, but less co-morbidity may be associated.

Nocturnal light effects on menstrual cycle length.

OBJECTIVES: In previous University of California, San Diego (UCSD) studies, nocturnal illumination shortened menstrual cycles that were longer than 33 days. The studies reported here extend the previous findings, confining the illumination to the sleep period. DESIGN: Two light levels (235 to 250 lux and less than 1 lux) and 2 modes of light delivery (lighted sleep mask and bedside lamp) were tested. RESULTS: 235 to 250 lux treatment cycle lengths were significantly shorter than baseline, but not significantly shorter than the less than 1 lux treatment cycle lengths. Subjective reports of sleep disturbance were greater with the 235 to 250 lux treatment, but there was no significant difference in overall quality of sleep between the two light levels. CONCLUSIONS: The current data alone do not exclude spontaneous remission or suggestion, but our previous studies demonstrated significant contrasts between 235 to 250 lux and less than 1 lux light levels. This study suggests that treatment may be effective when confined to the sleep period, and that light masks, which do not disturb bed partners, may be used in place of bedside lamps.

Morbidity, mortality and sleep-disordered breathing in community dwelling elderly.

A population-based probability sample of elderly individuals (n = 426), who were originally studied between 1981 and 1986 (mean age at initial study was 72.5 years), were followed for mortality. Those with > or = 30 respiratory disturbances per hour of sleep had significantly shorter survival (p = 0.0034), but the respiratory disturbance index (RDI) was not an independent predictor of death. When Cox proportional hazards analysis was done, only age (the strongest predictor), cardiovascular disease and pulmonary disease were independent predictors of death. It may be that factors that are secondary to or associated with sleep-disordered breathing (SDB), such as cardiovascular or pulmonary disease, predispose these elderly to death.