Is it nutrients, food items, diet quality or eating behaviours that are responsible for the association of children's diet with sleep?

Both diet quality and sleep duration of children have declined in the past decades. Several studies have suggested that diet and sleep are associated; however, it is not established which aspects of the diet are responsible for this association. Is it nutrients, food items, diet quality or eating behaviours? We surveyed 2261 grade 5 children on their dietary intake and eating behaviours, and their parents on their sleep duration and sleep quality. We performed factor analysis to identify and quantify the essential factors among 57 nutrients, 132 food items and 19 eating behaviours. We considered these essential factors along with a diet quality score in multivariate regression analyses to assess their independent associations with sleep. Nutrients, food items and diet quality did not exhibit independent associations with sleep, whereas two groupings of eating behaviours did. 'Unhealthy eating habits and environments' was independently associated with sleep. For each standard deviation increase in their factor score, children had 6 min less sleep and were 12% less likely to have sleep of good quality. 'Snacking between meals and after supper' was independently associated with sleep quality. For each standard deviation increase in its factor score, children were 7% less likely to have good quality sleep. This study demonstrates that eating behaviours are responsible for the associations of diet with sleep among children. Health promotion programmes aiming to improve sleep should therefore focus on discouraging eating behaviours such as eating alone or in front of the TV, and snacking between meals and after supper.