Nathaniel S. Marshall

Continuous positive airway pressure reduces daytime sleepiness in mild to moderate obstructive sleep apnoea: a meta-analysis

Background: Obstructive sleep apnoea syndrome (OSAS) affects an estimated 2–4% of the middle aged population. Meta-analyses of randomised controlled trials have shown that the severe presentation of the syndrome (apnoea hypopnoea index (AHI) >30/hour) is effectively treated with continuous positive airway pressure (CPAP). Until recently there have been insufficient data to determine whether CPAP improves sleepiness in the larger subgroup with mild to moderate OSAS (AHI 5–30/hour). Methods: A systematic search of Medline and a hand search identified seven randomised controlled trials where CPAP was compared with either a placebo or with conservative management in the treatment of mild to moderate OSAS (AHI 5–30/hour). All trials used the Epworth Sleepiness Scale (ESS), four used the Multiple Sleep Latency Test (MSLT), and three used the Maintenance of Wakefulness Test (MWT) to measure sleepiness. Results: Meta-analyses indicated that CPAP significantly reduced subjective daytime sleepiness (ESS) by 1.2 points (95% CI 0.5 to 1.9, p = 0.001), improved objective daytime wakefulness (MWT) by 2.1 minutes (95% CI 0.5 to 3.7, p = 0.011), but did not affect objective daytime sleepiness (MSLT, mean benefit −0.2 minutes, 95% CI −1.0 to 0.6, p = 0.6). The two significant effects were small (effect size <0.30). Conclusions: CPAP elicits small improvements in subjective sleepiness and objective wakefulness in people with mild to moderate OSAS. However, the effects on sleepiness are of limited clinical significance.

Sleep Apnea and 20-Year Follow-Up for All-Cause Mortality, Stroke, and Cancer Incidence and Mortality in the Busselton Health Study Cohort

OBJECTIVE To ascertain whether objectively measured obstructive sleep apnea (OSA) independently increases the risk of all cause death, cardiovascular disease (CVD), coronary heart disease (CHD), stroke or cancer. DESIGN Community-based cohort. SETTING AND PARTICIPANTS 400 residents of the Western Australian town of Busselton. MEASURES OSA severity was quantified via the respiratory disturbance index (RDI) as measured by a single night recording in November-December 1990 using the MESAM IV device, along with a range of other risk factors. Follow-up for deaths and hospitalizations was ascertained via record linkage to the end of 2010. RESULTS We had follow-up data in 397 people and then removed those with a previous stroke (n = 4) from the mortality/ CVD/CHD/stroke analyses and those with cancer history from the cancer analyses (n = 7). There were 77 deaths, 103 cardiovascular events (31 strokes, 59 CHD) and 125 incident cases of cancer (39 cancer fatalities) during 20 years follow-up. In fully adjusted models, moderate-severe OSA was significantly associated with all-cause mortality (HR = 4.2; 95% CI 1.9, 9.2), cancer mortality (3.4; 1.1, 10.2), incident cancer (2.5; 1.2, 5.0), and stroke (3.7; 1.2, 11.8), but not significantly with CVD (1.9; 0.75, 4.6) or CHD incidence (1.1; 0.24, 4.6). Mild sleep apnea was associated with a halving in mortality (0.5; 0.27, 0.99), but no other outcome, after control for leading risk factors. CONCLUSIONS Moderate-to-severe sleep apnea is independently associated with a large increased risk of all-cause mortality, incident stroke, and cancer incidence and mortality in this community-based sample.

Secular trends in adult sleep duration: A systematic review

OBJECTIVES Little evidence exists to support the common assertion that adult sleep duration has declined. We investigated secular trends in sleep duration over the past 40 years through a systematic review. METHODS Systematic search of 5 electronic databases was conducted to identify repeat cross-sectional studies of sleep duration in community-dwelling adults using comparable sampling frames and measures over time. We also attempted to access unpublished or semi-published data sources in the form of government reports, theses and conference proceedings. No studies were excluded based on language or publication date. The search identified 278 potential reports, from which twelve relevant studies were identified for review. RESULTS The 12 studies described data from 15 countries from the 1960s until the 2000s. Self-reported average sleep duration of adults had increased in 7 countries: Bulgaria, Poland, Canada, France, Britain, Korea and the Netherlands (range: 0.1-1.7 min per night each year) and had decreased in 6 countries: Japan, Russia, Finland, Germany, Belgium and Austria (range: 0.1-0.6 min per night each year). Inconsistent results were found for the United States and Sweden. CONCLUSIONS There has not been a consistent decrease in the self-reported sleep duration of adults from the 1960s to 2000s. However, it is unclear whether the proportions of very short and very long sleepers have increased over the same period, which may be of greater relevance for public health.

Continuous Positive Airway Pressure Reduces Postprandial Lipidemia in Obstructive Sleep Apnea A Randomized, Placebo-Controlled Crossover Trial

RATIONALE Dyslipidemia is common in Obstructive Sleep Apnea (OSA). Postprandial lipidemia (PPL) is a strong marker of cardiovascular risk. Evidence that OSA treatment improves PPL is lacking. OBJECTIVES To investigate the effect of continuous positive airway pressure (CPAP) treatment on postprandial lipidemia (PPL) in patients with obstructive sleep apnea (OSA) in the upper moderate or severe range. METHODS In this randomized, placebo-controlled crossover trial, we compared the effects of 2 months each of therapeutic and placebo CPAP on PPL. MEASUREMENTS AND MAIN RESULTS PPL was determined from the area under the 24-hour triglyceride concentration curve (TAG-AUC(24)) using seven blood samples drawn across both the wake and sleep periods. Secondary outcomes were the difference in other 24-hour lipid profiles. Thirty-eight eligible patients were randomly assigned to a treatment order and 29 patients completed the trial. CPAP reduced PPL compared with placebo with a mean TAG-AUC(24) difference of -357 mmol/L/d (95% confidence interval [CI], -687.3 to -26.8; P = 0.035). During both the CPAP and placebo studies, TAG levels peaked during both wakefulness (2:00 p.m.) and sleep (3:00 a.m.). Both peaks were lower during CPAP than placebo: 2:00 p.m., -0.49 mmol/L (95% CI, -0.74 to -0.24; P < 0.0005) and 3:00 a.m., -0.40 mmol/L (95% CI, -0.65 to -0.15; P = 0.002). Moreover, mean 24-hour total cholesterol was -0.19 mmol/L lower on CPAP (95% CI, -0.27 to -0.11; P < 0.00001). CONCLUSIONS This randomized trial demonstrated that treatment of severe OSA with CPAP improves postprandial TAG and total cholesterol levels. These effects may reduce the risk for cardiovascular events. The results imply that the association between OSA and cardiovascular disease may, in part, be caused by direct effects on dyslipidemia. Clinical trial registered with the Australian and New Zealand Clinical Trials Registry at www.anzctr.org.au (ACTRN 12605000066684).

SLEEP AND METABOLIC CONTROL: WAKING TO A PROBLEM?

1 The aim of the present review is to outline: (i) the association between sleep and metabolism; (ii) how sleep duration influences the development of disease; and (iii) how sex differences, ageing and obesity may potentially influence the relationship between sleep, metabolic control and subsequent disease. 2 Sleep is associated with a number of endocrine changes, including a change in insulin action in healthy young individuals. Sleep duration shows a prospective U‐shaped relationship with all‐cause mortality, cardiovascular disease and Type 2 diabetes. 3 Chronic sleep restriction is becoming more common. Experimental sleep restriction impedes daytime glucose control and increases appetite. 4 The sex hormones oestrogen and testosterone influence sleep duration and quality and may account for sex differences in the prevalence of sleep‐related disorders. 5 Ageing is associated with a decreased sleep duration, decreased muscle mass and impaired insulin action. 6 Obesity impairs insulin action and is associated with the incidence and severity of obstructive sleep apnoea. 7 Sleep plays an integral role in metabolic control. Consequently, insufficient sleep may represent a modifiable risk factor for the development of Type 2 diabetes. The challenge ahead is to identify how sex differences, ageing and obesity could potentially influence the relationship between sleep and metabolism.

Randomised controlled crossover trial of humidified continuous positive airway pressure in mild obstructive sleep apnoea

Background: It is unclear whether continuous positive airway pressure (CPAP), the treatment of choice for severe obstructive sleep apnoea (OSA), is effective at improving outcomes in mild OSA. Methods: To help define the role of humidified CPAP in mild OSA, a randomised crossover study was undertaken of patients with an apnoea hypopnoea index (AHI) of 5–30/hour. Subjective sleepiness, objective wakefulness, mood, reaction time, and quality of life were measured at baseline, after 3 weeks treatment with humidified CPAP and 3 weeks sham CPAP (2 week washout). Results: Twenty nine of 31 enrolled patients (age 25–67 years, seven women, mean (SD) body mass index 31.5 (6) kg/m2) completed the protocol. Humidified CPAP improved polysomnographic indices of OSA and Epworth Sleepiness Scale (2.4 points (95% CI 0.6 to 4.2)). Objective wakefulness (modified maintenance of wakefulness test) showed a trend towards improvement (5.2 minutes (95% CI −0.6 to 11)). Mood (Hospital Anxiety and Depression Scale), quality of life (SF 36, Functional Outcomes of Sleep Questionnaire), and reaction times (Psychomotor Vigilance Task) were not improved more than sham CPAP. Compliance with humidified and sham CPAP both averaged 4.9 hours/night. Placebo effects were evident in many outcomes and there was no clear treatment preference. Conclusions: Humidified CPAP improves subjective sleepiness and possibly objective wakefulness but not reaction times, quality of life, or mood. These results do not support the routine use of CPAP in all patients with mild OSA, but offers some support for the trialling of CPAP in those with severe sleepiness.

Sleep health New South Wales: chronic sleep restriction and daytime sleepiness

Aims: The aim of this study was to provide the first population‐based descriptions of typical sleep duration and the prevalence of chronic sleep restriction and chronic sleepiness in community‐dwelling Australian adults.

Sleeping at the Limits: The Changing Prevalence of Short and Long Sleep Durations in 10 Countries

Short (≤6 hours) and long (>9 hours) sleep durations are risk factors for mortality and morbidity. To investigate whether the prevalences of short and long sleep durations have increased from the 1970s to the 2000s, we analyzed data from repeated cross-sectional surveys of 10 industrialized countries (38 nationally representative time-use surveys; n = 328,018 adults). Logistic regression models for each country were used to determine changes in the prevalence of short and long sleep durations over time, controlling for sampling differences in gender, age, number of weekend days included, and season of data collection. Over the periods covered by data, the prevalence of short sleep duration increased in Italy (adjusted odds ratio = 2.64, 95% confidence interval (CI): 2.41, 2.89) and Norway (adjusted odds ratio = 2.33, 95% CI: 1.77, 3.08) but decreased in Sweden, the United Kingdom, and the United States. The prevalence of long sleep duration increased in Australia (adjusted odds ratio = 1.14, 95% CI: 1.05, 1.25), Finland (adjusted odds ratio = 1.30, 95% CI: 1.14, 1.48), Sweden (adjusted odds ratio = 1.51, 95% CI: 1.35, 1.69), the United Kingdom (adjusted odds ratio = 2.03, 95% CI: 1.68, 2.46), and the United States (adjusted odds ratio = 1.50, 95% CI: 1.36, 1.65) but decreased in Canada and Italy. No changes were observed in Germany or the Netherlands. Limited increases in short sleep duration challenge the claim of increasingly sleep-deprived societies. Long sleep duration is more widespread than is short sleep duration. It has become more prevalent and thus should not be overlooked as a potential contributor to ill health.

Sleep, sleepiness and motor vehicle accidents: a national survey

Objective:

Adolescent Sleep Patterns and Night-Time Technology Use: Results of the Australian Broadcasting Corporation's Big Sleep Survey

Introduction Electronic devices in the bedroom are broadly linked with poor sleep in adolescents. This study investigated whether there is a dose-response relationship between use of electronic devices (computers, cellphones, televisions and radios) in bed prior to sleep and adolescent sleep patterns. Methods Adolescents aged 11–17 yrs (n = 1,184; 67.6% female) completed an Australia-wide internet survey that examined sleep patterns, sleepiness, sleep disorders, the presence of electronic devices in the bedroom and frequency of use in bed at night. Results Over 70% of adolescents reported 2 or more electronic devices in their bedroom at night. Use of devices in bed a few nights per week or more was 46.8% cellphone, 38.5% computer, 23.2% TV, and 15.8% radio. Device use had dose-dependent associations with later sleep onset on weekdays (highest-dose computer adjOR  = 3.75: 99% CI  = 2.17–6.46; cellphone 2.29: 1.22–4.30) and weekends (computer 3.68: 2.14–6.32; cellphone 3.24: 1.70–6.19; TV 2.32: 1.30–4.14), and later waking on weekdays (computer 2.08: 1.25–3.44; TV 2.31: 1.33–4.02) and weekends (computer 1.99: 1.21–3.26; cellphone 2.33: 1.33–4.08; TV 2.04: 1.18–3.55). Only ‘almost every night’ computer use (: 2.43: 1.45–4.08) was associated with short weekday sleep duration, and only ‘almost every night’ cellphone use (2.23: 1.26–3.94) was associated with wake lag (waking later on weekends). Conclusions Use of computers, cell-phones and televisions at higher doses was associated with delayed sleep/wake schedules and wake lag, potentially impairing health and educational outcomes.