An overwhelming amount of evidence supports diet as an integral factor for determining health and wellbeing. In particular, diet quality overall appears to largely influence health, with the consumption of a healthy diet, often characterised as a Mediterranean-style diet, increasingly associated with positive health outcomes, whereas an unhealthy diet, usually described as a Western-style diet, generally associated with adverse health outcomes. Research now recognises diet as highly influential on mood and behaviour, as well as mental illnesses such as depression. In fact, evidence supports a healthy diet for reducing the odds and risk of depression, as well as dietary change as a potential preventative and therapeutic strategy.
However, whilst the answer appears simple – let’s all just eat healthy! – an overwhelmingly large number of people continue to eat energy-dense, nutrient-poor foods, consume excessive quantities of sugar-sweetened beverages, and over-indulge on snack foods. So, if we know the answer, why aren’t we changing our behaviours to prevent ill-health? Well, unfortunately as humans we are in fact MORE than what we eat, with a myriad of factors influencing what, when, where and how we eat. Therefore, when looking to assist people with dietary change, these factors cannot be overlooked, and also need to be modified to ensure dietary change can and will be maintained.
One of these factors is sleep, an essential part of life that we often take for granted, and who’s influence on health is often greatly over-looked. For example, people who experience regular disruptions to their sleep cycles or body clocks (circadian rhythm), such as chronic shift workers, are at an increased risk of developing pathological conditions such as obesity, diabetes, cancer and cardiovascular disease, and are more prone to infection. But what does sleep have to do with what we eat?
Research has found inadequate sleep to be associated with increased caloric consumption, poor dietary habits and obesity, as well as an increased amount of snacking. Inadequate sleep has also been associated with the consumption of more meals per day, and that the associated excess energy intake was more likely driven by eating for pleasure, rather than the need for energy. In particular, associations between sleep and diet have been found in children and adolescents. For example, a study of Portuguese children found that children who slept longer were more likely to have a diet consisting of fruits and vegetables, whereas those who slept less were more likely to consume a diet rich in fats and sugars. A cross-sectional study of adolescents found that those sleeping less than eight hours consumed more calories from fat and less from carbohydrate, and an increase in calories from consuming snacks. Interestingly, research also suggests that the association between sleep and diet is bidirectional, with the foods we ingest influencing how we sleep.
But, just like the answer to improving health by improving diet appears simple, improving sleep quality and duration comes with its own challenges. Inadequate sleep can largely be attributed to the increased usage of electronic devices in all age groups, particularly among adolescents, with 70% of Australian adolescents reported to have at least TWO electronic devices in their bedroom at night. Staring at stimulating screens, such as scrolling through social media, video gaming or watching Netflix, can affect sleep in a negative way, causing people to go to bed later, take longer to fall asleep, experience sleep disturbances and have less sleep overall. Furthermore, shorter sleep duration and sleeping difficulties associated with the use of electronic devices in bed before sleep have been associated with depressive symptoms.
So, what does this tell us? When looking at dietary research, sleep is an extremely important factor that should be taken into account in almost all diet-related studies. When educating the community, in particular young people, about the importance of nutrition and health, the influence of adequate, restful sleep on dietary patterns, and the importance of healthy media and device usage, should be integrated into the discussion. By looking at the entire picture, and addressing all aspects of health and lifestyle, researchers are more likely to assist people to make effective, long-term dietary changes to improve health and wellbeing.
Amelia McGuinness is an Australian Rotary Health Scholarship Holder and PhD candidate with the Food and Mood Centre leading the MICRO’SCOPE project.