To investigate the association between symptoms of long-term effects of coronavirus disease 2019 (long COVID) and sleep problems in a sample population from southern Brazil. This cross-sectional study used data from the SULcovid-19 survey, developed in the municipality of Rio Grande, RS, Brazil. The outcome, long COVID, was investigated through the presence of 18 symptoms, and the exposure variable was sleep problems. Poisson regression with robust adjustment for variance was used to estimate crude and adjusted prevalence ratios for the outcome-exposure relationship. Odds ratio was calculated through multinomial regression of the relationship between the number of symptoms of long COVID and sleep problems. Analyses were adjusted for sex, age, marital status, income, body mass index, smoking status, comorbidities, and hospital admission. A total of 2919 adults and older adults were interviewed. The prevalence of long COVID was 48.3% (95% confidence interval [CI] 46.5-50.1%) and sleep problems were reported by 41.2% of the sample (95% CI 39.4-43.0%). Individuals with sleep problems were more likely to exhibit altered sensitivity (prevalence ratio [PR] 3.27
95% CI 1.96-5.45), nasal congestion (PR 2.75
95% CI 1.53-4.94), musculoskeletal symptoms (PR 1.75
95% CI 1.48-2.06), respiratory issues (PR 1.58
95% CI 1.24-2.01), and one or more symptom of long COVID (PR 1.27
95% CI 1.15-1.39). Approximately one-half of the population analysed had long COVID, and four of 10 reported experiencing sleep problems. In addition, the sample tended to have experienced a greater number of symptoms compared with those who reported to sleep well.