BackgroundMedical trainees’ work schedule is designed to cover duties without consideration of differences in circadian rhythms during a 24-hour period (chronotype).ObjectiveTo explore chronotype variation among medical trainees and understand its association with burn-out and schedule satisfaction.MethodsIn a multicentre observational study, we conducted two surveys between 1 October 2018 and 1 April 2019. Trainees from nine centres across the USA participated. We measured burn-out using Maslach Burnout Inventory (MBI), and trainee chronotype using the Morningness-Eveningness Questionnaire (MEQ).Results324 (32%) out of 1012 responded to our survey. Participants were 51% female and had a mean age of 30.8 years. Most participants had an intermediate MEQ type (65%). A large proportion of participants had burn-out on at least one of three tested MBI scales (62%); 5% of participants had burn-out on all three MBI scales. More participants with evening MEQ type had burn-out (66%) compared with morning MEQ type (55%), however, the results were not statically significant (p=0.294). Overall satisfaction with work shifts was 6.5 (95% CI 6.3 to 6.7), with higher satisfaction with day shift 7.7 (95% CI 7.5 to 7.9) and lowest satisfaction with overnight 24-hour call 3.5 (95% CI 3.2 to 3.9). Satisfaction was lower in trainees with burn-out 6.0 (95% CI 5.7 to 6.4), (p<0.001). In the follow-up survey, burn-out was present in at least one scale in 64% compared with 60% of respondents in the initial survey.ConclusionBurn-out is prevalent among medical trainees. Improving alignment between trainee preferences may improve performance, reduce human errors and burn-out.