Sleep lengthening in late adulthood signals increased risk of mortality

Association between sleep duration from midlife to late life and the risk of depressive symptoms: the Singapore Chinese Health Study

BACKGROUND

The prospective association between sleep duration and the development of late-life depressive symptomology is unclear.

AIMS

To investigate sleep duration from midlife to late life in relation to risk of depressive symptoms in late life.

METHOD

A total of 14 361 participants from the Singapore Chinese Health Study were included in the present study. Daily sleep duration was self-reported at baseline (mean age of 52.4 years; 1993-98), follow-up 2 (mean age of 65.2 years; 2006-10) and follow-up 3 (mean age of 72.5 years; 2014-16) interviews. Depressive symptoms were evaluated using the Geriatric Depression Scale at follow-up 3 interviews. Modified Poisson regression models were performed to estimate relative risks and 95% confidence intervals of late-life depressive symptoms in relation to sleep duration at baseline and the two follow-up interviews.

RESULTS

Compared with sleeping 7 h per day, a short sleep duration of ≤5 h per day at baseline (i.e. midlife) was related to a higher risk of depressive symptoms (relative risk 1.10, 95% CI 1.06-1.15), and this risk was not affected by subsequent prolongation of sleep. Conversely, a long sleep duration of ≥9 h per day at baseline was not related to risk of depressive symptoms. At follow-up 3 (i.e. late life), both short sleep (relative risk 1.20, 95% CI 1.16-1.25) and long sleep (relative risk 1.12, 95% CI 1.07-1.18) duration were cross-sectionally associated with depressive symptoms.

CONCLUSION

Short sleep duration in midlife, regardless of subsequent prolongation, is associated with an increased risk of depression in late life. Contrariwise, both short and long sleep duration in late life co-occur with depressive symptoms.

The Effect of Acute Sleep Extension on Blood Pressure Is Dependent on the Change in Sleep Efficiency

The present study investigated the effect of acute sleep extension on blood pressure and microvascular vasodilation. Sleep and daily physical activity were objectively measured at home for two weeks using wrist actigraphy in 22 adults (60 ± 15 y). Vascular measurements were made in the morning on the 8th and 15th day. Participants spent at least 10 h in bed on the night prior to one of these testing days to extend sleep. Mean arterial blood pressure (MAP) and peak reactive hyperemia in the forearm were measured on each testing day. Reactive hyperemia and MAP were unaltered (p > 0.05) by sleep extension in the total sample. However, adults who experienced improved sleep efficiency with sleep extension (n = 10, 4.2 ± 1.4%) exhibited reduced MAP (-5.5 ± 4.6 mm Hg, p = 0.005) while adults who had little change or decreased sleep efficiency (n = 12, -1.7 ± 2.9%) showed no change in MAP. The reduction in MAP was significantly different between sleep efficiency groups (p = 0.005, Hedges' g = 1.21) after adjustment for sex and moderate-to-vigorous physical activity. The results of this study suggest that sleep extension has the potential to reduce blood pressure in midlife to older adults when the additional sleep time improves the quality of sleep.

Sleep Behaviors and Progression of Multimorbidity in Middle-Aged and Older Adults: A Prospective Cohort Study From China

BACKGROUND

Sleep behavior (eg, sleep duration, sleep quality, and nap) is closely related to many chronic conditions. However, less is known about its association with multiple chronic conditions (multimorbidity), particularly evidence from cohort studies.

METHODS

Data were collected from a cohort of 8 937 individuals aged 45 and older from the China Health and Retirement Longitudinal Study (2011-2018). Sleep duration, sleep quality, and nap duration were collected in 2011 and 2013. Progression of multimorbidity was defined as the first report of 2 or more chronic conditions for participants without multimorbidity or the new report of 1 or more conditions for those with multimorbidity. Cox regression models were performed to calculate the hazard ratios and 95% confidence intervals (CIs) of the associations between sleep behaviors and the progression of multimorbidity.

RESULTS

Short sleep duration and poor sleep quality were associated with the progression of multimorbidity independently and jointly, especially in those less than 65 years and females. The U-shaped dose-response relationships were observed between nighttime and total sleep duration and the progression of multimorbidity. Persistent short and unsteadily changed sleep behaviors increased the risk of multimorbidity progression. Individuals sleeping ≤5 h/night with 5-7 restless days/week had 1.53 times higher risk of multimorbidity progression (95% CI: 1.37-1.71), compared to those sleeping 7-8 h/night with <1 restless day/week.

CONCLUSIONS

Short sleep duration and poor sleep quality were independently and jointly associated with a higher risk of multimorbidity progression in a mid-to-older population. Optimal sleep duration and sleep quality should be emphasized in multimorbidity prevention and control.

Sleep duration trajectories and all-cause mortality among Chinese elderly: A community-based cohort study

BACKGROUND

China is among the largest and fastest aging countries. The elderly population is more vulnerable, with higher proportion of inappropriate sleep duration and risk of mortality, compared with young and middle-aged adults. Single-measured sleep duration has been associated with mortality, but the health effects of long-term sleep duration trajectories remain unknown. This study aimed to explore the prospective associations between sleep duration trajectories and all-cause mortality among Chinese elderly.

METHODS

Participants (n = 3,895; median age: 82 years; females: 53.3%) who reported sleep duration in all three surveys (2005, 2008, and 2011) from the community-based Chinese Longitudinal Healthy Longevity Survey (CLHLS) were followed up until 2019 (about 8 years). We identified sleep duration trajectories by latent class mixed model and explored their association with all-cause mortality using Cox hazard proportional regression and Laplace regression models. Further, stratified analysis by demographic characteristics and lifestyles and sensitivity analysis by lag effect, health-related factors, and inverse probability weighting were used to verify the robustness of the association. In addition, we explored the threshold effect of baseline sleep duration on the risk of all-cause mortality.

RESULTS

We documented 1,881 all-cause deaths during 16,689 person-years of follow-up. Five sleep duration trajectories were identified: moderately increased trajectory (28.1%), rapidly increased trajectory (7.2%), persistent sleep trajectory of 7 h (33.7%), moderately decreased trajectory (21.3%), and rapidly decreased trajectory (9.7%). Compared with the persistent sleep trajectory of 7 h, the multivariable-adjusted HRs (95%CI) for moderately increased trajectory, rapidly increased trajectory, moderately decreased trajectory, and rapidly decreased trajectory were 1.21 (1.08, 1.36), 1.21 (1.01, 1.44), 0.95 (0.82, 1.10), and 0.93 (0.78, 1.11), respectively; and the corresponding difference in median survival time (95%CI) were -0.53 (-1.01, -0.05), -0.43 (0.16, -1.02), 0.26 (-0.34, 0.86), and 0.25 (-0.51, 1.02), respectively. Stratified and sensitivity analyses showed consistent results. Threshold analysis indicated a sharply increased risk of mortality in participants whose sleep exceeds 9 h (HR = 1.20, 95%CI: 1.11, 1.30).

CONCLUSION

Compared with the persistent sleep trajectory of 7 h, moderately and rapidly increased sleep duration trajectories were associated with higher subsequent mortality in Chinese elderly. Those who report sleep exceeding 9 h may be at high risk for all-cause mortality.

Prospective associations between change in sleep duration and cognitive impairment: Findings from the Singapore Chinese Health Study

BACKGROUND

The relation of changes in sleep duration with risk of cognitive impairment are inconclusive. This study evaluated the prospective relationships of changes in sleep duration with risk of cognitive impairment in Singapore Chinese.

METHODS

We used data from 16,948 Chinese men and women who were aged 45-74 years at baseline (1993-1998) during recruitment into the Singapore Chinese Health Study cohort. Daily sleep duration was assessed at baseline, follow-up 2 (2006 to 2010) and follow-up 3 interviews (2014-2016). Cognitive function was evaluated with a Singapore-Modified Mini-Mental State Examination at follow-up 3 interviews when participants were 61-96 years old. Multivariable logistic regression models were used to calculate odd ratios (ORs) and 95% confidence intervals (95% CIs) for cognitive impairment.

RESULTS

Of the 16,948 participants, 14.4% were defined to have cognitive impairment. Compared with 7 h/day sleep at both baseline and follow-up 2, the OR (95% CI) for cognitive impairment was 1.50 (1.04-2.16) for those who maintained long sleep duration (≥9 h/day), 2.18 (1.37-3.45) for those who prolonged sleep from short duration (≤5 h/day) to long duration (≥9 h/day), and 1.55 (1.20-2.02) for those who prolonged sleep from recommended duration (7 h/day) to long duration. The highest risk was observed in those who shortened sleep from long to short duration (2.93, 1.35-6.34).

LIMITATIONS

Measures of sleep were self-reported.

CONCLUSIONS

Substantial changes in sleep duration over time were associated with higher risks of cognitive impairment. The findings underscore the importance of maintaining optimal sleep duration for the prevention of cognitive impairment.

Sleep duration and all-cause mortality in the elderly in China: a population-based cohort study

Background

Although a U-shaped association between sleep duration and all-cause mortality has been found in general population, its association in the elderly adults, especially in the oldest-old, is rarely explored.

Methods

In present cohort study, we prospectively explore the association between sleep duration and all-cause mortality among 15,092 participants enrolled in the Chinese Longitudinal Healthy Longevity Survey (CLHLS) from 2005 to 2019. Sleep duration and death information was collected by using structured questionnaires. Cox regression model with sleep duration as a time-varying exposure was performed to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs). The dose-response association between them was explored via a restricted cubic spline function.

Results

During an average follow-up of 4.51 (standard deviation, SD: 3.62) years, 10,768 participants died during the follow-up period. The mean (SD) age of the participants was 89.26 (11.56) years old. Compared to individuals with moderate sleep duration (7–8 hours), individuals with long sleep duration (> 8 hours) had a significantly higher risk of all-cause mortality (HR: 1.13, 95%CI: 1.09–1.18), but not among individuals with short sleep duration (≤ 6 hours) (HR: 1.02, 95%CI: 0.96–1.09). Similar results were observed in subgroup analyses based on age and gender. In the dose-response analysis, a J-shaped association was observed.

Conclusions

Sleep duration was associated with all-cause mortality in a J-shaped pattern in the elderly population in China.

Delayed sleep-onset and biological age: late sleep-onset is associated with shorter telomere length

STUDY OBJECTIVES

We evaluated the relationship between leukocyte telomere length (LTL) and sleep duration, insomnia symptoms, and circadian rhythm, to test whether sleep and chronobiological dysregulations are associated with cellular aging.

METHODS

Data from the Netherlands Study of Depression and Anxiety (N = 2,936) were used at two waves 6 years apart, to measure LTL. Telomeres shorten during the life span and are important biomarkers for cellular aging. LTL was assessed by qualitative polymerase chain reaction and converted into base pair number. Sleep parameters were: sleep duration and insomnia symptoms from the Insomnia Rating Scale. Circadian rhythm variables were: indication of Delayed Sleep Phase Syndrome (DSPS), mid-sleep corrected for sleep debt on free days (MSFsc), sleep-onset time, and self-reported chronotype, from the Munich Chronotype Questionnaire. Generalized estimating equations analyzed the associations between LTL, sleep, and chronobiological factors, adjusted for baseline age, sex, North European ancestry, and additionally for current smoking, depression severity, obesity, and childhood trauma.

RESULTS

Indicators of delayed circadian rhythm showed a strong and consistent effect on LTL, after adjustment for sociodemographic and health indicators. Late MSFsc (B = -49.9, p = .004), late sleep-onset time (B = -32.4, p = .001), indication of DSPS (B = -73.8, p = .036), and moderately late chronotype in adulthood (B = -71.6, p = .003) were associated with significantly shorter LTL across both waves; whereas sleep duration and insomnia symptoms were not. Extremely early chronotype showed significantly less LTL shortening than intermediate chronotype (B = 161.40, p = .037). No predictors showed accelerated LTL attrition over 6 years.

CONCLUSIONS

Individuals with delayed circadian rhythm have significantly shorter LTL, but not faster LTL attrition rates.

The Role of Cognitive Impairment, Physical Disability, and Chronic Conditions in the Association of Sleep Duration With All-Cause Mortality Among Very Old Adults

OBJECTIVE

This study aimed to examine the relationship between sleep duration and all-cause mortality, and to assess the role of cognitive impairment, physical disability, and chronic conditions on this association among very old adults.

DESIGN

A prospective cohort study.

SETTING AND PARTICIPANTS

Within the Chinese Longitudinal Healthy Longevity Surveys, 17,637 oldest-old aged 80-105 years were followed up to 10 years (2005- 2014).

MEASURES

Data on sleep duration at baseline were based on self-report and were categorized as short (<7 hour), moderate (7-9 hours), and long sleep (>9 hours). Information on cognitive function using the Mini-Mental State Examination (MMSE), physical disability using Activities of Daily Living (ADL), and chronic conditions including diabetes, heart disease, stroke, asthma, and cancer were collected at baseline based on a structured questionnaire. Information about vital status was ascertained and confirmed by a close family member or village doctor of the participant during the follow-up. Data were analyzed using Cox proportional hazards models, with adjustment for potential confounders.

RESULTS

During the follow-up of 10 years, 11,067 (62.7%) participants died. The multivariate-adjusted hazard ratios (HRs) with 95% confidence interval (CI) for mortality were 1.03 (0.98-1.09) for short sleep and 1.13 (1.08-1.18) for long sleep compared with moderate sleep duration. In stratified analysis by cognitive impairment, physical disability, and chronic conditions, the risk of morality was present only among people with MMSE scores ≤24 but did not differ much when stratified by physical disability and chronic conditions. There was a statistically significant interaction between long sleep and cognitive impairment on mortality (P for interaction = .002).

CONCLUSIONS AND IMPLICATIONS

Long sleep duration is associated with higher risk of mortality in very old adults independently of health conditions. Cognitive impairment may enhance this association. These findings suggest that health practitioners and families should be aware of the potential adverse prognosis associated with long sleep.

Association between total sleep time and all cancer mortality: non-linear dose-response meta-analysis of cohort studies

OBJECTIVE

Appropriate total sleep time is reported to be associated with several important health outcomes. However, the relationship between total sleep time and all cancer mortality is not well defined because of inconsistent results from published studies, and no dose-response meta-analysis was performed to evaluate the exact dose-response relationship.

METHODS

We conducted a literature search of PubMed and Web of Science to identify all relevant epidemiological studies published before August 9, 2018. We performed categorical and non-linear dose-response meta-analyses to quantify the association between total sleep time and all cancer mortality.

RESULTS

Finally, we included 14 cohort studies in the present meta-analyses enrolling 866,877 participants with 43,021 cancer deaths. We found that total sleep time less than seven hours was not significantly associated with increased risk of all cancer mortality [relative risk (RR) = 1.02; 95% confidence interval (CI) = 0.99-1.05]. However, four to five hours total sleep time was related to an 8% increased risk of all cancer mortality (RR = 1.08; 95% CI = 1.02-1.13) in dose-response meta-analysis. Furthermore, long total sleep time (≥8 hours) was weakly associated with all cancer mortality (RR = 1.05; 95% CI = 1.02-1.08). However, the increment in total sleep time longer than nine hours was notably associated with an increased risk of cancer mortality.

CONCLUSION

The current meta-analysis provides evidence of a positive association between total sleep time of four to five hours and total sleep time longer than eight hours with the risk of all cancer mortality among the general population. Additional studies are needed to establish causality.

The association between sleep duration and cancer-specific mortality: a systematic review and meta-analysis

PURPOSE

In this systematic review and meta-analysis, we aimed to estimate cancer-specific mortality and all-cause mortality among cancer survivors associated with both short (typically 5 or 6 h/night) and long (typically 9 or 10 h/night) sleep duration (versus recommendations), separately by sex, cancer site, and sampling frame.

METHODS

We completed a systematic literature search in five databases and captured relevant literature published through December 2018. Two reviewers independently screened 9,823 records and 32 studies were included representing over 73,000 deaths in cancer survivors. Estimates for short and long sleep duration compared to 'recommended' were pooled using random-effects models.

RESULTS

Pooled hazards ratios for short and long sleep duration for all-cancer-specific mortality were 1.03 (95% CI 1.00-1.06) and 1.09 (95% CI 1.04-1.13), respectively. In subgroup analyses by cancer site, statistically significant increased risks were found for both short and long sleep durations for lung cancer-specific mortality. These associations were maintained when stratified by sex and sampling frame. There were no statistically significant associations found between either short or long sleep duration and breast, colorectal, ovarian, or prostate cancer-specific mortality. Statistically significant increases in all-cause mortality were observed with long sleep duration in breast cancer survivors (1.38; 95% CI 1.16-1.64) with no significant associations found for colorectal or liver/pancreatic cancers.

CONCLUSIONS

We observed that long sleep duration increases cancer-specific mortality for all-cancers and lung cancers, while all-cause mortality is increased for breast cancer survivors. Limitations were found within the existing literature that need to be addressed in future studies in order to improve the understanding regarding the exact magnitude of the effect between sleep duration and site-specific mortality.

Sleep duration and risk of end-stage renal disease: the Singapore Chinese Health Study

OBJECTIVES

Although epidemiological evidence suggests that short sleep duration may affect renal function, the influence of long sleep and risk of end-stage renal disease (ESRD) is unclear. We examined the association between sleep duration and risk of ESRD.

METHODS

We investigated sleep duration and ESRD risk in the Singapore Chinese Health Study, a prospective population-based cohort of 63,257 Chinese in Singapore, who were aged 45-74 years at recruitment (1993-1998). Information on daily sleep duration (including naps), diet, medical history and other lifestyle factors was collected at recruitment from in-person interviews. ESRD cases were identified via linkage with the nationwide Singapore Renal Registry through year 2014. We used the Cox proportional hazards regression method to estimate hazard ratio (HR) and 95% confidence interval (CI) of ESRD in relation to sleep duration.

RESULTS

After an average 16.8 years of follow-up, 1143 (1.81%) ESRD cases were documented. Sleep duration had a U-shaped association with risk of ESRD (P for quadratic trend < 0.001). Compared with participants with 7 h/day of sleep, the multivariable adjusted HR (95% CI) of ESRD was 1.43 (1.18-1.74) for short sleep (≤5 h/day) and 1.28 (1.03-1.60) for long sleep duration (≥9 h/day). The increased risk was stronger in participants with more than 10 years of follow-up compared to those with shorter follow-up time, especially for long sleep (P for interaction = 0.003).

CONCLUSIONS

Our findings demonstrated that both short and long sleep durations were associated with a higher risk of ESRD in this Asian population.