Long working hours in health professionals have been linked to sleep deprivation, dietary changes and burnout, with potential variation by sex and migration-related background. Evidence from large professional samples in Spain describing these patterns by sex and birthplace is limited.To assess the association between long working hours (>40 hours/week) and sociodemographic and health-related behaviours, exploring patterns by sex and birthplace (born in Spain vs outside Spain).Cross-sectional survey (2021) administered to professionals affiliated with the Medical Association of the Province of Barcelona. Data included sociodemographics (sex, age group, birthplace), health behaviours (physical activity; sleep duration <6 vs ≥6 hours; appetite changes; diet), burnout and substance use. We estimated the prevalence of long working hours and compared proportions by sex and birthplace using chi-square tests. We fitted binary logistic regression models to identify asociations with long working hours, including analyses stratified by sex and birthplace.Among 2,261 respondents, 38.5% reported working >40 hours/week. Long working hours were more common in men than women (43.2% vs 37.1%; p=0.0139) and did not differ by birthplace (40.0% born outside Spain vs 38.4% born in Spain; p=0.6739). Moderate-to-severe client-related burnout was higher among those born outside Spain (28.9% vs 19.5%; p=0.00094). In regression models, long working hours were associated with sleeping <6 hours, reporting a less healthy diet than usual and higher coffee consumption; older age showed a protective association. Some associations differed in magnitude across sex and birthplace strata.In this sample, long working hours affected over one third and were more prevalent among men. The co-occurrence of long working weeks with sleep and dietary disruption supports plausible pathways linking workload to health risk. Higher burnout among respondents born outside Spain highlights potential structural vulnerabilities warranting focused analyses.Long working hours were frequent among Barcelona health professionals and were linked to potentially modifiable behaviours, particularly sleep and diet. Occupational-health strategies addressing work-time demands should integrate sex- and birthplace-sensitive approaches.