Yue Leng

Sleep duration and risk of fatal and nonfatal stroke A prospective study and meta-analysis

Objective: To study the association between sleep duration and stroke incidence in a British population and to synthesize our findings with published results through a meta-analysis. Methods: The prospective study included 9,692 stroke-free participants aged 42–81 years from the European Prospective Investigation into Cancer–Norfolk cohort. Participants reported sleep duration in 1998–2000 and 2002–2004, and all stroke cases were recorded until March 31, 2009. For the meta-analysis, we searched Ovid Medline, EMBASE, and the Cochrane Library for prospective studies published until May 2014, and pooled effect estimates using a weighted random-effect model. Results: After 9.5 years of follow-up, 346 cases of stroke occurred. Long sleep was significantly associated with an increased risk of stroke (hazard ratio [HR] = 1.46 [95% confidence interval (CI) 1.08, 1.98]) after adjustment for all covariates. The association remained robust among those without preexisting diseases and those who reported sleeping well. The association for short sleep was smaller (and not statistically significant) (HR = 1.18 [95% CI 0.91, 1.53]). There was a higher stroke risk among those who reported persistently long sleep or a substantial increase in sleep duration over time, compared to those reporting persistently average sleep. These were compatible with the pooled HRs from an updated meta-analysis, which were 1.15 (1.07, 1.24) and 1.45 (1.30, 1.62) for short and long sleep duration, respectively. Conclusions: This prospective study and meta-analysis identified prolonged sleep as a potentially useful marker of increased future stroke risk in an apparently healthy aging population.

Daytime Napping and the Risk of All-Cause and Cause-Specific Mortality: A 13-Year Follow-up of a British Population

Epidemiologic studies have reported conflicting results on the relationship between daytime napping and mortality risk, and there are few data on the potential association in the British population. We investigated the associations between daytime napping and all-cause or cause-specific mortality in the European Prospective Investigation Into Cancer-Norfolk study, a British population-based cohort study. Among the 16,374 men and women who answered questions on napping habits between 1998 and 2000, a total of 3,251 died during the 13-year follow-up. Daytime napping was associated with an increased risk of all-cause mortality (for napping less than 1 hour per day on average, hazard ratio = 1.14, 95% confidence interval: 1.02, 1.27; for napping 1 hour or longer per day on average, hazard ratio = 1.32, 95% confidence interval: 1.04, 1.68), independent of age, sex, social class, educational level, marital status, employment status, body mass index, physical activity level, smoking status, alcohol intake, depression, self-reported general health, use of hypnotic drugs or other medications, time spent in bed at night, and presence of preexisting health conditions. This association was more pronounced for death from respiratory diseases (for napping less than 1 hour, hazard ratio = 1.40, 95% confidence interval: 0.95, 2.05; for napping 1 hour or more, hazard ratio = 2.56, 95% confidence interval: 1.34, 4.86) and in individuals 65 years of age or younger. Excessive daytime napping might be a useful marker of underlying health risk, particularly of respiratory problems, especially among those 65 years of age or younger. Further research is required to clarify the nature of the observed association.

Self-reported sleep patterns in a British population cohort

Highlights • Our study provides a subjective sleep profile of a large British population–based cohort.• The reported time in bed (TIB) was more than 1.5 h longer than sleep duration.• All sociodemographic factors varied with TIB and sleep duration.• Sleep proportion may be a useful indicator of sleep patterns in this population.

Daytime napping, sleep duration and serum C reactive protein: a population-based cohort study

Objectives To explore whether daytime napping and sleep duration are linked to serum C reactive protein (CRP), a pro-inflammatory marker, in an older aged British population. Design Cross-sectional study. Setting European Prospective Investigation into Cancer and Nutrition (EPIC)-Norfolk study. Participants A total of 5018 men and women aged 48–92 years reported their sleep habits and had serum CRP levels measured. Outcome and measures CRP was measured (mg/L) during 2006–2011 in fresh blood samples using high-sensitivity methods. Participants reported napping habits during 2002–2004, and reported sleep quantity during 2006–2007. Multivariable linear regression models were used to examine the association between napping and log-transformed CRP, and geometric mean CRP levels were calculated. Results After adjustment for age and sex, those who reported napping had 10% higher CRP levels compared with those not napping. The association was attenuated but remained borderline significant (β=0.05 (95% CI 0.00 to 0.10)) after further adjustment for social class, education, marital status, body mass index, physical activity, smoking, alcohol intake, self-reported health, pre-existing diseases, systolic blood pressure, hypnotic drug use, depression and in women-only hormone replacement therapy use. The geometric means (95% CI) of CRP levels were 2.38 (2.29 to 2.47) mg/L and 2.26 (2.21 to 2.32) mg/L for those who reported napping and no napping, respectively. A U-shaped association was observed between time spent in bed at night and CRP levels, and nighttime sleep duration was not associated with serum CRP levels. The association between napping and CRP was stronger for older participants, and among extremes of time spent in bed at night. Conclusions Daytime napping was associated with increased CRP levels in an older aged British population. Further studies are needed to determine whether daytime napping is a cause for systemic inflammation, or if it is a symptom or consequence of underlying health problems.

Association of Sleep-Disordered Breathing With Cognitive Function and Risk of Cognitive Impairment: A Systematic Review and Meta-analysis

Importance Growing evidence suggests an association between sleep-disordered breathing (SDB) and cognitive decline in elderly persons. However, results from population-based studies have been conflicting, possibly owing to different methods to assess SDB or cognitive domains, making it difficult to draw conclusions on this association. Objective To provide a quantitative synthesis of population-based studies on the relationship between SDB and risk of cognitive impairment. Data Sources PubMed, EMBASE, and PsychINFO were systematically searched to identify peer-reviewed articles published in English before January 2017 that reported on the association between SDB and cognitive function. Study Selection We included cross-sectional and prospective studies with at least 200 participants with a mean participant age of 40 years or older. Data Extraction and Synthesis Data were extracted independently by 2 investigators. We extracted and pooled adjusted risk ratios from prospective studies and standard mean differences from cross-sectional studies, using random-effect models. This meta-analysis followed the PRISMA guidelines and also adhered to the MOOSE guidelines. Main Outcomes and Measures Cognitive outcomes were based on standard tests or diagnosis of cognitive impairment. Sleep-disordered breathing was ascertained by apnea-hypopnea index or clinical diagnosis. Results We included 14 studies, 6 of which were prospective, covering a total of 4 288 419 men and women. Pooled analysis of the 6 prospective studies indicated that those with SDB were 26% (risk ratio, 1.26; 95% CI, 1.05-1.50) more likely to develop cognitive impairment, with no evidence of publication bias but significant heterogeneity between studies. After removing 1 study that introduced significant heterogeneity, the pooled risk ratio was 1.35 (95% CI, 1.11-1.65). Pooled analysis of the 7 cross-sectional studies suggested that those with SDB had slightly worse executive function (standard mean difference, −0.05; 95% CI, −0.09 to 0.00), with no evidence of heterogeneity or publication bias. Sleep-disordered breathing was not associated with global cognition or memory. Conclusions and Relevance Sleep-disordered breathing is associated with an increased risk of cognitive impairment and a small worsening in executive function. Further studies are required to determine the mechanisms linking these common conditions and whether treatment of SDB might reduce risk of cognitive impairment.

Daytime napping, sleep duration and increased 8-year risk of type 2 diabetes in a British population

Background and aims Few studies have prospectively examined the relationship between daytime napping and risk of type 2 diabetes. We aimed to study the effects of daytime napping and the joint effects of napping and sleep duration in predicting type 2 diabetes risk in a middle- to older-aged British population. Methods and results In 1998–2000, 13 465 individuals with no known diabetes participating in the European Prospective Investigation into Cancer-Norfolk study reported daytime napping habit and 24-h sleep duration. Incident type 2 diabetes cases were identified through multiple data sources until 31 July 2006. After adjustment for age and sex, daytime napping was associated with a 58% higher diabetes risk. Further adjustment for education, marital status, smoking, alcohol intake, physical activity, comorbidities and hypnotic drug use had little influence on the association, but additional adjustment for BMI and Waist Circumference attenuated the Odds ratio (OR) (95% CI) to 1.30 (1.01, 1.69). The adjusted ORs (95% CI) associated with short and long sleep duration were 1.46 (1.10, 1.90) and 1.64 (1.16, 2.32), respectively. When sleep duration and daytime napping were examined together, the risk of developing diabetes more than doubled for those who took day naps and had less than 6 h of sleep, compared to those who did not nap and had 6–8 h of sleep. Conclusion Daytime napping was associated with an increased risk of type 2 diabetes, particularly when combined with short sleep duration. Further physiological studies are needed to confirm the interaction between different domains of sleep in relation to diabetes risk.

Daytime napping and increased risk of incident respiratory diseases: symptom, marker, or risk factor?

Highlights • Daytime napping was associated with 32–54% increase in respiratory incidence risk.• The association was more pronounced for chronic lower respiratory diseases.• The association was independent of comorbidities and a proxy measure of sleep apnea.• Excessive daytime napping might be an early marker of incident respiratory diseases.• Further studies are needed to help understand potential mechanisms.

A population study of the association between sleep disturbance and suicidal behaviour in people with mental illness

Limited representative research has considered the relationship between sleep disturbance and suicidal behaviour among people with mental illness. We investigated the relationship between sleep disturbance and suicidal behaviour across Part II interview of the National Comorbidity Survey Replication (NCSR). The associations between sleep disturbance and suicidal behaviour (thoughts, plans and attempts) were investigated using logistic and multinomial logistic regressions and stratified across six mental disorder groups (depression, anxiety, substance use disorders (SUD), eating disorders (ED), bipolar disorders (BD) and early life disorders). From 5701 participants (mean age 43.4 years 58% women), people with any mental disorder experiencing sleep disturbance were at increased odds of suicidal thoughts (odds ratio (OR): 2.5; 95% CI: 1.7, 3.6) and suicidal plans and attempts (OR: 5.7; 95% CI: 2.7, 11.9) adjusting for age, sex and income. People with BD (OR: 8.9; 95 CI: 2.1, 38.1), early life disorders (OR 6.98, 95% ci 2.48, 19.67), depression (OR 1.88, 95% CI 1.14, 3.11), anxiety (OR 1.90, 95% CI 1.28, 2.85) and SUD (2.60, 95% CI 1.23, 5.49) but not ED, were at increased odds of suicidal thoughts in the presence of sleep disturbance. Adjusting for anti-depressant intake attenuated the effect sizes by up to 20% but the associations remained significant. In conclusion, sleep disturbance is a potential risk factor for suicidal behaviours in people with mental illness. Monitoring and management of sleep disturbance in clinical practice might be an important strategy to mitigate suicidal behaviours in people with mental illness.

Antidepressant Use and Cognitive Outcomes in Very Old Women

Background Antidepressant use is very common in the elderly, but the effects of antidepressants on cognition in the elderly are controversial with some studies suggesting harm and others protection. We aimed to investigate the association between different antidepressant use and change in cognition and risk of mild cognitive impairment (MCI) or dementia in very old women. Methods We examined 1,234 community-dwelling women (mean age 83.2 years) from the Study of Osteoporotic Fractures. Baseline antidepressant use was reported and verified by medication containers, and medications were coded with computerized dictionary. Cognitive status (normal, MCI, or dementia) was adjudicated by an expert clinical panel 5 years later. Change in a short-form Mini-Mental State Examination and Trails B were evaluated over 5 years. Results Eleven per cent of the women were taking antidepressants. Users of selective serotonin reuptake inhibitors (SSRIs) had the greatest cognitive decline over 5 years, after adjustment for demographics, medical comorbidities, benzodiazepine use, and baseline cognition. Multivariable logistic regression shows that the users of SSRIs were more than twice (OR = 2.69, 95% CI = 1.64-4.41) and trazodone users more than three times (3.48, 1.12-10.81) as likely to develop MCI or dementia compared with the nonusers. Further adjustment for baseline cognition or depressive symptoms did not appreciably alter the results, and the association remained after excluding women with high depressive symptoms. The use of tricyclic antidepressants or other antidepressants was not significantly associated with cognitive outcomes. Conclusions The use of antidepressants, especially SSRIs and trazodone, was associated with an increased risk of cognitive impairment 5 years later among the oldest old women.

Excessive daytime sleepiness, objective napping and 11-year risk of Parkinson’s disease in older men

Background It is unknown whether subjective daytime sleepiness or objective napping could precede the risk of Parkinsons disease (PD) in the long term. Methods We studied 2920 men (mean age 76 years) without a history of PD and followed them for 11 years. Excessive daytime sleepiness (EDS) was defined as having an Epworth Sleepiness Scale score >10. Objective naps were defined as ≥5 consecutive minutes of inactivity as measured by actigraphy, and napping duration was the accumulated time of naps outside the main sleep period. We used logistic regression to compare PD risk across four groups: no EDS& napping <1 h/day (N = 1739, 59.5%; referent group), EDS& napping <1 h/day (N = 215, 7.4%), no EDS& napping ≥ 1 h/day (N = 819, 28.1%) and EDS& napping ≥ 1 h/day (N = 147, 5.0%). Results We identified 106 incident PD cases over 11 years. After multivariable adjustment, men with napping  ≥  1h/day alone were twice as likely [odds ratio (OR) = 1.96, 95% confidence interval (CI) 1.25-3.08], and men with both EDS and napping  ≥ 1 h/day were almost three times as likely to develop PD (2.52, 1.21-5.27), compared with the referent group. Compared with those with naps for <30 min, men who napped for  ≥1 h/day had more than double the risk of PD. No association was found for EDS alone and PD risk. Further adjustment for chronotype and circadian stability, or excluding PD cases identified within 2 years after napping measurements, showed similar results. Conclusions Objective long napping rather than subjective EDS was prospectively associated with a higher risk of PD in older men. Objective measures of napping might be valuable as a preclinical marker for PD.