Runners are in the thick of holiday party season which means that their sugar intake is probably at an annual high (aside from maybe birthdays or halloween). A new study from The American Journal of Clinical Nutrition suggests that sugar intake, or other foods with a high glycemic index, could be responsible for insomnia.
The 2019 study looked at the association between intake of specific types of carbs and their effect on poor sleep. They found that participants with higher glycemic diets showed more likelihood of incidental or prevalent insomnia. Glycemic index is a ranking of carbohydrates according to how they affect blood-sugar levels. High glycemic foods includes alcohol, candy and white bread. Low glycemic foods include whole wheat bread, oatmeal and fruits and vegetables.
Earlier studies have also found that poor quality of sleep is linked with poor dietary habits, which creates a vicious cycle. Runners sleep poorly, so they eat poorly which leads them to continue sleeping poorly. In 2017 a group of researchers from King’s College in London found that people who sleep longer are less likely to reach for carb-heavy, calorie dense comfort foods or the classic mid-afternoon sugary snack. Racking up more zzz’s during the night meant that people made better food choices through their day.
While a few days of holiday indulgence is totally normal, a continued cycle of poor nutrition choices could have negative effects on sleep longterm. And for runners in particular, consistent, high quality sleep is arguably the cheapest and most effective training tool. Canadian W50 marathon record holder Denise Robson says that sleep was her biggest asset in the build to her record-breaking race. “I have three biological children and four foster children. Now that my foster children are gone, there are more hours in the day. I was able to come home after a Sunday long run, shower, eat and take a two- to three-hour nap. That made a huge difference in training.”