- Title
- An exploration of the relationship between sleep health and dietary intake in adults, and the implications for weight management
- Creator
- Fenton, Sasha
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2020
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Background: The high prevalence of overweight and obesity is one of the greatest public health challenges facing the world today, exposing many individuals to the development of non-communicable chronic diseases. Prevention and management of overweight and obesity is complex in an ‘obesogenic’ environment saturated with energy-dense foods in combination with low levels of physical activity and high levels of sedentary behaviour. Lifestyle interventions, which routinely target improvements in physical activity and dietary intake are moderately effective in adults in the short- to medium-term (≤18 months). However, longer-term weight loss and weight maintenance can be challenging for many individuals; weight regain is frequently reported. Reduced adherence to physical activity and diet prescriptions may be one reason for this. Accumulating evidence suggests that insufficient sleep is a novel risk factor for the development of overweight and obesity. Research indicates that increased energy intake due to insufficient sleep mediates the relationship between sleep and overweight and obesity, attributed in part to higher frequency of food consumption, especially at night. However, sleep health, as a construct, is multidimensional, comprising duration, quality, efficiency, timing, and daytime alertness. Currently, the relationship between indicators of sleep health beyond sleep duration, and dietary intake, and the implications these relationships may have on weight management is unclear. It is also unclear whether targeting and improving indicators of sleep health in a weight loss intervention may produce greater improvements in dietary intake, which could subsequently assist with longer-term successful weight management. Objectives: (1) To systematically review and quantify the effect of the multiple dimensions of sleep health on dietary intake in adults in intervention studies; (2) To compare the relative efficacy of a physical activity, diet, and sleep behaviour-change weight loss intervention, with a physical activity and diet behaviour-change weight loss intervention on dietary intake in adults with overweight and obesity; and, (3) To examine how changes in physical activity, diet, and sleep behaviours mediate reduced daily energy intake in adults with overweight and obesity during a behaviour-change weight loss intervention. Methods and results: Objective 1 (Chapter Three): Five electronic databases were searched using predefined keywords to identify studies published between 1970 and 2019 that modified sleep and reported dietary outcomes. Fifty-four full texts were assessed and 24 publications were included. Following risk of bias appraisal, data were narratively summarised and a sub-group of studies (n=15) was meta-analysed to determine the effect of short sleep duration on dietary intake. One intervention modified sleep timing and 23 modified sleep duration. In the interventions, sleep duration was partially restricted (≤5.5 h per night) (n= 16), totally restricted (n= 4), partially and totally restricted (n= 1), and extended (n= 2). Dietary outcomes were energy intake (n= 24), carbohydrate, fat, protein intake (n= 20), single nutrient intake (n= 5), diet quality (n= 1) and food types (n= 1). Meta-analysis indicated partial sleep restriction results in higher energy intake in intervention compared with control (SMD= 0.37; 95% CI= 0.21, 0.52; p <0.001), with a mean difference of 204 kcal (95% CI= 112, 295; p <0.001) in daily energy intake, and a higher percentage of energy from fat, protein, and carbohydrate. Objective 2 (Chapter Five): This objective was investigated in a 3-arm randomised controlled trial (RCT), the Move, Eat & Sleep study, in a sample of 116 adults with overweight and obesity. Participants were randomised to either: traditional physical activity and diet intervention; enhanced physical activity, diet, and sleep intervention; or wait-list control. The traditional intervention, with a six month primary endpoint and follow-up at 12 months provided education, feedback, and tools to set goals and self-monitor dietary and physical activity behaviours. The enhanced intervention provided the same components, with an additional sleep intervention that promoted good sleep health and operationalised sleep hygiene practices and components of Cognitive Behaviour Therapy for insomnia (CBT-i). To examine between-group differences, intervention groups were pooled and compared with the control. The two intervention groups were then compared. At six and 12 months there were no significant differences reported in sleep quality scores or sleep duration between the pooled intervention and control groups, and the enhanced and traditional groups. At six months, the pooled intervention group consumed 1,011 fewer kilojoules per day (95% CI -1922, -101), less sodium (-313.2 mg/day; 95% CI -591.3, -35.0), and higher percentage of energy intake (%EI) from fruit (+2.1 %EI; 95% CI 0.1, 4.1) than the control group. There were no differences in dietary intake between the enhanced and traditional groups at six months. At 12 months, the pooled intervention and control groups reported no significant differences in dietary intake. However, compared to the traditional group, at 12 months the enhanced group reported higher %EI from protein (+2.4%EI; 95% CI 0.1, 4.6) and nutrient-dense foods (+7.4%EI; 95% CI 1.3, 13.5), and reduced %EI from energy-dense nutrient-poor foods (-7.4 %EI; 95% CI -13.5, -1.3; p= 0.017). Objective 3 (Chapter Six): Using data from the Move, Eat & Sleep study, this objective was investigated in a mediation analysis. For this study the two intervention groups were pooled and compared with the control. Structural equation modelling was used to estimate the mediated effects of the intervention on energy intake. A range of hypothesised physical activity, diet, and sleep mediators were modelled separately as potential mediators. The mediated intervention effects were estimated using a product of coefficients approach, and bias-corrected bootstrapped confidence intervals were calculated and used for the interpretation of results. The significant intervention effect on energy intake at six months (-1011 kJ/day; SE= 464; 95% CI -1922, -101; d= 0.55) was partially mediated by reduced fat (total) intake (AB= -761.12; 95% CI -1564.25, -53.74) and reduced consumption of energy-dense, nutrient-poor foods (AB= -576.19; 95% CI -1189.23, -97.26). These mediators explained 78.6% and 53.9% of the intervention effect, respectively. Conclusion: This thesis presents evidence that short sleep duration increases energy intake in adults, which may have significant implications in both the prevention and treatment of overweight and obesity, and for the risk of the development of some non-communicable chronic diseases. The findings suggest that improving sleep may provide additional benefit to dietary intake and weight management, and provide new evidence for clinical practice and future research. However, the efficacy of including a dedicated sleep intervention in a multiple behaviour-change weight loss intervention to elicit greater improvements in dietary intake remains unclear and warrants further research. This research also identified that experimental studies have predominantly examined the effect of restricted sleep duration on energy intake, with minimal consideration given to the effect of other dimensions of sleep health on dietary intake, such as sleep quality and sleep timing. As an emerging area of research there has also been minimal consideration given thus far to the impact that improvement in sleep health may have on dietary intake. These relationships are important to understand as they may have implications for weight management and chronic disease risk, particularly in the significant proportion of the adult population that experiences sleep problems.
- Subject
- sleep health; dietary intake; physical activity; weight loss; RCT; mHealth; thesis by publication
- Identifier
- http://hdl.handle.net/1959.13/1495147
- Identifier
- uon:53972
- Rights
- Copyright 2020 Sasha Fenton
- Language
- eng
- Full Text
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