We all know that feeling. Waking up sleep deprived and reaching for a caffeinated beverage, sugary snack or a carb hit to make it through the day. But just how much does our sleep shape what we eat and vice versa?
There are actually several theories about how and why sleep length and quality can influence what and how much you eat.
Some are psychological theories; that we seek reward and comfort from food when we feel poorly as we do after an interrupted night’s sleep. Or that sleep deprivation means there are simply more hours in the day to consume extra food and drink. Or that our taste perceptions change and we seek out hyper palatable foods for a quick energy hit. There have been randomised trials showing that after sleep restriction our brain reward regions light up on functional MRIs at being shown unhealthy foods.
There is also evidence that sleep length and quality influences key hormones that are important to dietary intake. Leptin, for example, reduces appetite, regulates energy intake and can influence weight. Ghrelin on the other hand, increases appetite, hunger and our desire for hyper palatable foods.
Poor sleep can mess with the balance of these hormones – leptin decreases and ghrelin increases. This results in us feeling more hungry throughout the day, and less full from our meals. This hormonal imbalance resulting from poor sleep can also influence our energy expenditure. For example, we may be less inclined to be physically active after a bad night’s sleep. But because hormonal factors like how much fat tissue you carry can influence this balance and our eating behaviours, it is not a straight forward relationship.  That’s why we see health behaviours like sleep, physical activity, nutrition and substance use cluster; they are so intricately linked.
What is good sleep?
Sleep length and quality can determine a good sleep. Good quality sleep is that which makes us wake up feeling well rested, replenished and refreshed. The Sleep Foundation has recommendations for different age groups regarding sleep length.
Just like poor quality sleep can affect dietary choices, good sleep can promote better food choices. Good quality sleep means you may be less likely to experience those physiological and psychological barriers that can lead to us seeking out hyper palatable foods. There is also some evidence that those who sleep better report higher self efficacy (self belief) that drives better nutrition and lifestyle behaviours. You can understand why this might be the case as you may be more likely to meal plan, cook home made meals and the like if you feel replenished after a good night’s sleep.
If you would like tips on how to improve your sleep, check out our resource page.
To listen to a discussion on how sleep is related to your mental health, hear Professor O’Neil on 774 ABC Radio’s Conversation Hour where we discuss this in more detail.
Professor Adrienne O’Neil is a behavioural scientist at the Food & Mood Centre who specialises in promoting the use and quality of evidence-based lifestyle medicine and rehabilitation in mental health and cardiac settings.