Diet and sleep in Australian middle aged and elder men

Abstract

Optimal sleep duration and quality sleep are an important cornerstone for good health. Poor sleep can lead to a series of adverse consequences in metabolic and immune systems, as well as in mortality. Research into the effects of diet on sleep have mainly focused on single macronutrients and laboratory studies. Not yet explored are the complex interactions between dietary intake and chronic disease, psychosocial and lifestyle factors in relation to sleep at the population level. This thesis aims to investigate the complexity of the association between dietary factors and sleep outcome (objective and subjective measures) middle aged and elderly Australian men. Data used in the thesis were from the Men Androgen Inflammation Lifestyle Environment and Stress (MAILES) study, established to determine the explanatory variables, and help with treatment and preventive measures, for the development of chronic diseases in men. The studies undertaken in this thesis firstly examined the association between macronutrients intake and the risk of sleep apnoea and self-reported sleep symptoms in men aged 35-80 years old. This study found that compared with the lowest quartile of fat intake, the highest quartile was associated with increased risks of daytime sleepiness and sleep apnoea events during the night. No associations were observed between carbohydrate and protein and sleep parameters. The studies undertaken secondly determined dietary patterns in the same population, and explored the association between these dietary patterns and sleep parameters. Three dietary patterns were identified: the prudent pattern that is characterized by fruits, vegetables and legumes and the western pattern that is characterized by processed meat, snacks, red meat and take-away foods, and the mixed pattern that is a combination of these two patterns. The prudent pattern is associated with faster sleep onset, but no other associations were found between dietary patterns and sleep outcomes. Dietary effects on inflammation have been widely studied, but no studies have linked dietary inflammation with sleep disorders. The final study examined the association between nutrient patterns and inflammation, as well as the interactions between nutrient patterns and obstructive sleep apnoea (OSA), lifestyle factors, and chronic diseases. An animal-sourced pattern (characterized by animal protein, cobalamin, cholesterol and omega-6) was positively associated with inflammation, while a plant-sourced pattern (characterized by beta-carotene, vitamin A, lutein and zeaxanthin) was inversely associated with inflammation. The association between the plant-sourced pattern and CRP was stronger in participants with sedentary lifestyle, high level of OSA, but without diabetes or dyslipidaemia. No associations were found between the vitamin B and folate pattern (characterized by total folate, thiamine, riboflavin and niacin) and inflammatory markers. These studies confirmed the associations between dietary factors and sleep parameters at the population level. A general low fat and plant-based diet may improve sleep. In addition, a comprehensive understanding among diet, sleep disorders and inflammation and chronic diseases is highlighted. These findings have significant implications in public health and clinical management of chronic inflammation.