Healthy carbohydrates are associated with better sleep
Our guest:
Associate Professor Marie-Pierre St-Onge
I recently wrote a post about how what we eat can affect how we sleep and referred to some interesting research by Marie-Pierre St-Onge, Associate Professor of Nutritional Medicine and Director of the Sleep Center of Excellence, at Columbia University Irving Medical Center, New York. Lately, I have noticed a great interest in so called low carb diets such as the Keto diet and the early version of the Atkins diet. One of the desired effects of low carb diets is to reduce our blood sugar levels, the result being that the body starts to burn fat which in turn facilitates weight loss. However, from a holistic point of view, which means taking into consideration the whole body and mind and their functions, diets that exclude or restrict large groups of nutrients can have undesirable side effects. Modern research shows that carbohydrates may play an important role in our sleep, but unfortunately many people who choose low carb diets are unaware of these findings. To bring more clarity around the issue, I have the pleasure of interviewing one of the top experts in the field, Associate Professor Marie-Pierre St-Onge.
Can a low-carb diet affect our sleep negatively?
At the moment, there has not been a study specifically examining the impact of a low-carbohydrate diet on sleep. There is one study that I know of that examined sleep quality in participants undergoing a very low calorie ketogenic diet but that study is confounded by changes in body weight and did not have a control group. In short, they showed improvements in sleep quality in the reduced ketosis phase of the diet but this was also the time of maximal weight loss. Of note is that sleep quality rebounded somewhat when ketosis was no longer present but remained better than baseline. So there could be an interact of change in weight and ketosis on sleep. But again, there was no control group. We have a better idea of the influence of carbohydrate quality on sleep. Studies show that diets with higher carbohydrate quality, higher in whole grains, fiber, and low glycemic index foods, are associated with better sleep and lower risk of insomnia. In our research, consumption of higher fiber and less refined carbohydrates was associated with deeper sleep and less arousals at night.
What are the mechanisms behind this effect?
It is possible that high intakes of simple sugars, particularly in the evening, delays circadian rhythms of core body temperature and reduces melatonin concentrations, which would support our findings of higher arousals. This could also be due to high blood glucose levels after a meal triggering higher secretion of insulin that can cause precipitous reduction in blood glucose resulting in arousals. Higher GI foods also stimulate inflammation and compromise gut microbiome which have also been implicated in sleep homeostasis.
Is the effect of carbohydrates immediate or long-lasting?
In our study, the effects were observed after a single day. Population studies track dietary and sleep patterns over a longer period of time. In our work related to high glycemic index foods and insomnia, participants (all women in that study) were followed for 3 years. So I would say the effects are immediate and long-lasting.
Should we be careful to include healthy carbohydrates in our last meal of the day?
I would recommend eating healthy carbohydrates throughout the day! But, of course, those high sugar foods close to bedtime would not help one’s sleep.
What is your main take-home message when it comes to food and sleep?
I like to take a holistic approach and focus on high quality of all 3 macronutrients but beyond macronutrients, include nutritious foods. On a macronutrient level, this means more fiber/less refined carbohydrates, more unsaturated fats relative to saturated fats (the latter we’ve found being related to less deep sleep), and plant-based proteins and proteins rich in tryptophan (the building block for serotonin and melatonin). On a food level, this means focusing on whole grains, fruits and vegetables, legumes, nuts & seeds, and liquid oils. Many plant foods also provide exogenous sources of melatonin that could benefit sleep. Choosing more of those foods (for example tart cherries, tomatoes, salmon, yogurt, nuts, oats contain melatonin; fish, seeds, tofu, whole grains, turkey, lamb contain tryptophan) can contribute to healthier sleep at night.
Ketosis – A metabolic process that occurs when the body does not have enough glucose for energy. Stored fat is burnt and so-called ketone bodies are created. These are used for energy instead of glucose.
Macronutrients – The three macronutrients are protein, carbohydrates and fat. They are needed in large amounts for the body to work properly.
Exogenous source – Coming from outside of the body, e.g. food.
