The relationship between chronic sleep restriction, poor sleep quality and obesity in adults

This thesis consists of two literature reviews followed by three empirical chapters that examined the relationship between chronic sleep restriction and obesity. Chapter 2 reviewed available research data and presented a theoretical model linking chronic sleep restriction to obesity. This model hypothesises that chronic sleep restriction contributes to obesity by altering energy regulatory hormones such as ghrelin and leptin. It was also argued that factors such as poor mental health, medication use and long work hours contribute to chronic sleep restriction at a population level, and could have implications for improving sleep. This model provides a sound theoretical framework, which was used to guide the subsequent empirical chapters. In chapter 3, the key methodological limitations of previous studies examining the relationship between chronic sleep restriction and obesity were outlined. Methodological recommendations for future research were then provided to facilitate a more complete understanding of how chronic sleep restriction and obesity are linked in the general population. Chapter 4 tested a path model linking chronic sleep restriction to obesity in 325 adults aged 18 to 87 years, based on the theoretical framework provided in chapter 2 and the methodological recommendations listed in chapter 3. The results indicated that short sleep durations and age were associated with obesity, whilst age, uncomfortable sleep environments, irregular sleep/wake cycles and poor mental health were associated with short sleep durations. However, the results also identified potential environmental, behavioural and psychological determinants of chronic sleep restriction that could be targeted in the future treatment and prevention of obesity. Chapter 5 examined the relationship between three dimensions of sleep quality as assessed by the Pittsburgh Sleep Quality Index and obesity in 262 adults aged 18 to 35 years. Short sleep durations and increased levels of daytime dysfunction (e.g., sleepiness) were associated with obesity, whilst irregular bedtimes, noisy environments, discomfort and depression were the major factors associated with poor sleep quality. These factors could play a role in obesity interventions that target sleeping patterns and need to be further investigated. Finally, chapter 6 examined the effects of two nights of seep restriction on energy expenditure and neuroendocrine hormones involved in energy balance regulation in ten healthy male adults. The results indicated that sleep restriction led to an increase in ghrelin and a reduction in PYY, which corresponded with increased hunger and reduced satiety. The results also suggested that energy expenditure declined with sleep restriction. These results suggest that sleep restriction could contribute to obesity by altering energy expenditure and the hormonal regulation of food intake. The findings from this thesis therefore suggest that chronic sleep restriction contributes to the development of obesity by altering key pathways identified in chapter 2. The identification of possible determinants of chronic sleep restriction has potential applications for the treatment and prevention of obesity. For example, the factors identified in chapters 4 and 5 could be targeted as a way to promote healthy sleep durations, and could be effective in improving the efficacy of existing interventions for obesity

The Progress in Wireless Data Transport and its Role in the Evolving Internet

The progress of wireless technology through the past 105 years is quantitatively reviewed in this paper. Spectral efficiency and coverage density are both found to increase in a relatively continuous exponential fashion over the entire period with spectral efficiency increasing at about 15% per year and coverage density at about 33% per year. Throughput by wireless technology was not found to follow a single exponential but instead followed an exponential with annual increase of only 5% up to the late 70s and since then (and the introduction of the cellular concept) has followed an exponential with annual increases of greater than 50%. These high rates of progress in the functional performance of wireless technology are an essential enabler for wireless interfaces to become the dominant mode for connecting to the Internet

Parental employment and child behaviors: Do parenting practices underlie these relationships?

This study examined whether hours of parental employment were associated with child behaviors via parenting practices. The sample included 2,271 Australian children aged 4-5 years at baseline. Two-wave panel mediation models tested whether parenting practices that were warm, hostile, or characterized by inductive reasoning linked parent\u27s hours of paid employment with their child\u27s behavior at age 6-7 years. There were significant indirect effects linking mother employment to child behavior. No paid employment and full-time work hours were associated with more behavioral problems in children through less-warm parenting practices; few hours or long hours were associated with improved behavioral outcomes through less-hostile parenting practices. These findings may have implications for developing policies to enable parents to balance work and family demands

Measuring older patients’ attitudes to general practice registrars: Exploratory factor analysis of a survey instrument

Introduction: Training general practice registrars (GPRs) to meet the challenges of an ageing population is hampered by their relatively reduced contact with older patients and a paucity of suitable research to inform training models. This paper describes an exploratory factor analysis of a survey instrument assessing the attitudes of older patients to GPRs, as part of a project to address these concerns. Methods: The instrument was developed on the basis of a qualitative study and a literature review and distributed to 500 patients aged 60 years and over from 10 training practices in regional Australia. Responses to 22 of the survey’s Likert scale items were examined, including inter-item correlations and internal consistency (Cronbach’s alpha). Exploratory factor analysis was performed to identify domains of patients’ attitudes. Results: The response rate was 39.2% (n=196). None of the items were redundant and the scale had appropriate levels of internal consistency (Cronbach’s alpha = 0.76). The exploratory factor analysis identified three factors. Factor one, labelled ‘interpersonal trust’, explained 26.2% of the variance. Factor two accounted for 11.4% of the variance and was labelled ‘system trust’. Factor three, labelled ‘interpersonal continuity’, explained 7.5% of the variance. Conclusion: The instrument demonstrated acceptable psychometric properties and three distinct factors reflecting older patients’ attitudes toward GPRs, with trust appearing to be particularly important. The instrument appears effective in obtaining valid data, which should assist in developing improved training models. These findings warrant confirmation with a larger sample and exploration of adaptations of the instrument to be used in other contexts. Keywords: general practice registrar; post-graduate training; patient attitude

Chasing the thrill or just passing the time? Trialing a new mixed methods approach to understanding heterogeneity amongst recreational fishers based on motivations

Human dimensions researchers and fisheries managers have long recognized the value of exploring the heterogeneity that exists amongst recreational fishers. Understanding the differences between fishers has the potential to assist managers in developing targeted communication strategies, direct resources to active management more efficiently and improve understanding of how fishers will respond to changes in regulations or new management interventions. Human dimensions research has traditionally explored fisher heterogeneity through research into the different reasons why people choose to fish, as well as attempts to categorize or segment fishers using variable based approaches. These studies have, to date, relied primarily on large scale, quantitative survey techniques with a particular focus on fisher avidity and commitment. They are therefore limited in their ability to explain how different fishing motivations might interact within an individual, why particular motivations are prioritized, and how this might influence fisher behavior and attitudes. This study trialed a mixed methods approach to understanding fisher heterogeneity based primarily on motivations using a case study in NSW, Australia. This trial involved utilizing a person-centered approach known as Latent Class Analysis (LCA), followed by qualitative, in depth focus group discussions. This revealed five distinct fisher classes; Social fishers, Trophy Fishers, Outdoor Enthusiasts, Generalists and Hunter-Gatherers, each with distinct and significantly different combinations of catch and non-catch-related motivations. The qualitative analysis sought to explore the intersection of motivations and attitudes towards management within and across the different fisher classes. The results highlighted the importance of more detailed examination of the intersection between motivations and attitudes in future LCA, with a particular focus on the potential influence of mastery (or challenge/experience) motivations on fisher attitudes to wards marine and fisheries management approaches

Is the Australian smoking population hardening?

Background The hardening hypothesis proposes that as smoking rates decline, the remaining smokers will become hardcore and resistant to quitting. This group of highly resistant quitters will potentially require more individualistic approaches to cessation and harm reduction. The harm reduction approach (specifically e-cigarettes) has been proposed as an option to address hardened Australian smokers. We tested the hardening hypothesis by analysing the rates of hardcore smoking in the Australian smoking population between 2010-2016. Methods Data were drawn from three waves of the National Drug Strategy Household Survey (NDSHS) in 2010, 2013 and 2016. Two different definitions were used to assess hardcore smoking to arrive at an upper and lower rate. Logistic regression assessed hardcore smoker characteristics for both definitions of hardcore smoker. Results The most inclusive definition of hardcore smoking (i.e., a smoker with no plan to quit) showed a significant decline in hardcore smoking between 2010 and 2016 (5.49% - 4.85%) In contrast, the prevalence of hardcore smoking using the most stringent definition (i.e., a current daily smoker of at least 15 cigarettes per day, aged 26 years or over, with no intention to quit, a lifetime consumption of at least 100 cigarettes, and no quit attempt in the past 12 months) did not change significantly between 2010 and 2016. Conclusion The observed trends in the prevalence of hardcore smokers (i.e., either stable or declining depending on the definition) suggest that the Australian smoking population is not hardening. These results do not support claims that remaining smokers are becoming hardcore

Examining the Pathways Linking Chronic Sleep Restriction to Obesity

A growing number of studies have identified chronic sleep restriction as a potential risk factor for obesity. This could have important implications for how obesity is prevented and managed, but current understanding of the processes linking chronic sleep restriction to obesity is incomplete. In this paper, we examined some of the pathways that could underlie the relationship between chronic sleep restriction and obesity. This involved exploring some of the potential environmental, health, behavioral, and sociodemographic determinants of chronic sleep restriction, which require further investigation in this context. Three pathways that could potentially link chronic sleep restriction to obesity were then examined: (1) altered neuroendocrine and metabolic function, (2) impaired glucose regulation, and (3) waking behavior. The selected pathways linking chronic sleep restriction to obesity reviewed in this paper are presented in a schematic representation; this may be used to guide future research in this area. This area of research is important because it may lead to more effective interventions and strategies to combat the present obesity epidemic

Short sleep duration is associated with risk of future diabetes but not cardiovascular disease: a prospective study and meta-analysis

Epidemiologic studies have observed association between short sleep duration and both cardiovascular disease (CVD) and type 2 diabetes, although these results may reflect confounding by pre-existing illness. This study aimed to determine whether short sleep duration predicts future CVD or type 2 diabetes after accounting for baseline health. Baseline data for 241,949 adults were collected through the 45 and Up Study, an Australian prospective cohort study, with health outcomes identified via electronic database linkage. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals. Compared to 7h sleep, <6h sleep was associated with incident CVD in participants reporting ill-health at baseline (HR=1.38 [95% CI: 1.12-1.70]), but not after excluding those with baseline illness and adjusting for baseline health status (1.03 [0.88-1.21]). In contrast, the risk of incident type 2 diabetes was significantly increased in those with <6h versus 7h sleep, even after excluding those with baseline illness and adjusting for baseline health (HR=1.29 [1.08-1.53], P=0.004). This suggests the association is valid and does not simply reflect confounding or reverse causation. Meta-analysis of ten prospective studies including 447,124 participants also confirmed an association between short sleep and incident diabetes (1.33 [1.20-1.48]). Obtaining less than 6 hours of sleep each night (compared to 7 hours) may increase type 2 diabetes risk by approximately 30%.The Sax Institute; Cancer Council New South Wales; the National Heart Foundation of Australia (New South Wales Division); The New South Wales Ministry of Health; Beyondblue: the National Depression Initiative; Ageing, Disability and Home Care, New South Wales Family and Community Services; the Australian Red Cross Blood Service; Uniting Care Ageing; the Australian National Health and Medical Research Council

Failure of interpolation in the intuitionistic logic of constant domains

This paper shows that the interpolation theorem fails in the intuitionistic logic of constant domains. This result refutes two previously published claims that the interpolation property holds.Comment: 13 pages, 0 figures. Overlaps with arXiv 1202.1195 removed, the text thouroughly reworked in terms of notation and style, historical notes as well as some other minor details adde

Area level socioeconomic disadvantage and diabetes control in the SIMLR Study cohort: Implications for health service planning

Abstract of a poster presentation at the 2015 PHC Research Conference, Adelaide, 29-31 July, 2015