This study, which aimed to examine the relationship between sleep quality and diet quality in adults, was conducted on 50 adults residing in Bursa province and known not to use sleeping pills. The researchers via face-to-face interviews completed a questionnaire, querying the personal characteristics, sleep duration and sleep quality of the participants. The daily food consumption data of the participants were recorded using the retrospective recall method. Diet quality and sleep quality were measured using the Healthy Eating Index-2015 (HEI-2015) and Pittsburgh Sleep Quality Index (PSQI), respectively. Most of the participants were female (62%) and aged 25-44 years (68%). The groups with good and poor sleep quality significantly differed for caffeine intake (p < 0.05). No statistically significant correlation was observed between sleep quality and other nutrients including vitamin A, calcium and iron (p > 0.05). While no statistically significant correlation was determined between sleep quality and the HEI overall diet quality score (p > 0.05), the HEI components, the wholegrain score displayed a statistically significant negative correlation with the overall sleep quality score (p < 0.05). In this study, no statistically significant correlation was determined between overall diet quality and sleep quality, but caffeine intake and wholegrain consumption were ascertained to significantly affect sleep quality.