Introduction: We sought to systematically review the association between meal glycemic index or glycemic load and sleep indicators.
Evidence acquisition: PubMed, Scopus, Web of Science, and Embase were searched up to March 2021. Both observational and clinical trials studies, with both male and female participants of all ages, were included.
Evidence synthesis: A total of 10 studies were included in this review; six with clinical trial and four with cross-sectional design. Among the six clinical trial, three studies indicated a significant effect of high glycemic index on sleep (two in young male athletes [N.=8 and N.=9] and one in adults [N.=8]), while three others failed to detect any significant effect (young males [N.=12], children [N.=8], toddlers [N.=56]). Among the cross-sectional studies, high glycemic index meals were associated with improved sleep duration or quality in two studies (594 toddlers and 1848 adults), however, contrastingly, were also associated with sleep disturbances (108 students and 53,069 postmenopausal women).
Conclusions: High glycemic index meals likely improve sleep onset latency in young males. For other indicators of sleep quality and other population groups, the results are equivocal. Most of the available studies were conducted in special population groups and were inadequately designed; whilst clinical trials were of short duration and small sample sizes. Therefore, further well-designed clinical trials are required before further definitive conclusions can be made.