OBJECTIVES: to investigate the association between the adherence to the 2018 World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) recommendations and the prevalence of parameters of sleep quality and quantity in people with metabolic syndrome (MS). DESIGN: cross-sectional study. SETTING AND PARTICIPANTS: 126 people with MS included in a randomized controlled trial of Mediterranean diet and metformin for the primary prevention of age-related chronic diseases (Me.Me.Me. study) wore for one week an actigraph called Actiwatch to assess restful sleep parameters (sleep efficiency – SE, actual sleep time – AST, immobile time – IT) and fragmented sleep parameters (moving time – MT, movement and fragmentation index – MFI, sleep latency – SL). At the baseline visit, each participants completed a 24-hour food frequency diary listing what he/she ate the previous day, and the International Physical Activity Questionnaire. These questionnaires were used to build up a score for adherence to seven relevant 2018 WCRF/AICR recommendations. MAIN OUTCOME MEASURES: the prevalence ratios (PRs) and 95% confidence intervals (CIs) of sleep parameters associated with each recommendation and with the number of met recommendations were calculated using a binomial regression model. RESULTS: the PRs for SE>=85% and IT>=84% increased with the number of met recommendations. Meeting 5-7 recommendations compared to 0-2 was associated with a better SE (PR 3.24 for SE>=85%; p=0.03) and IT (PR 1.68 for IT>=84%; p=0.04). The PRs for MFI>=34.5 and SL>=18 minutes decreased with the number of met recommendations. Meeting 5-7 recommendations compared to 0-2 was associated with a 46% lower prevalence of MFI (p=0.02) and 40% lower prevalence of SL (p=0.04). CONCLUSIONS: the findings of this paper suggest that the prevalence of better sleep quality in people with MS might be associated with closer adherence to 2018 WCRF/AICR recommendations.