Dietary inflammatory index (DII) and sleep quality, duration, and timing: A systematic review

Sleep has strong inflammatory underpinnings and diet is one of the primary determinants of systemic inflammation. A systematic literature review was conducted to synthesize current research associating dietary inflammatory potential, as measured by the dietary inflammatory index (DII®) or the energy-adjusted DII (E-DII™) and sleep quality and duration. The National Library of Medicine (Medline), Web of Science, and PsycInfo databases were searched through March 2023. Studies must have used the DII/E-DII as the independent variable and sleep outcomes as dependent variables. Study characteristics, based on STROBE guidelines, were scored based on the presence of the recommendation. Out of the initial 14 studies identified, a total of 12 studies were included for data synthesis. In all 12 studies, more anti-inflammatory diets (i.e., low DII/E-DII scores) were associated with better sleep in at least one sleep domain (most often sleep efficiency and wake-after-sleep-onset). Among those studies with more rigorous diet and sleep measurements, such as dietary recalls and actigraphy, associations between DII/E-DII and sleep outcomes were stronger and more consistent compared to studies using primarily subjective assessments. More rigorous measurement of diet and sleep, especially those relating to sleep stage structure, should be considered in future studies with prospective designs.