Background The poor sleep quality is an important cause for psychiatric disorders as well as shift work affects the quantity and quality of sleep.

Objective To evaluate the association of sleep-related problems with minor psychiatric disorders (MPD) among shift workers in southern Brazil.

Methods Cross-sectional study carried out with 1202 workers (aged: 18 to 50 yrs). MPD was assessed using the Self-Reporting Questionnaire (SRQ-20) and sleep-related problems were evaluated by the four following characteristics: sleep restriction (5 hours or less per day), difficulty in falling asleep, waking up during sleeping hours and sleep medication use. Multivariable analyses were performed by Poisson regression and all analyses were stratified by gender.

Results The prevalence of MPD was 26.8% (95% CI: 24.3–29.3) among the total workers being more prevalent among females than males (30.2% vs. 20.4%; p < 0.001). The presence of one sleep problem in the sample was 37.5% (95% CI: 34.8–40.3) whereas 20.7% (95% CI: 18.5–23.1) was classified as having two or more sleep problems. Sleep problems were associated with increased age, lower schooling and work on the night shift for both genders. Nightshift workers exhibited a significant association with sleep-related problems. After adjusting for confounding factors, sleep-related problems showed a positive linear trend with MPD. The prevalence ratios for MDP were 1.38 (95% CI: 0.86–2.20) and 3.25 (95% CI: 2.07–5.11) in the males with one sleep problem and two or more sleep problems, respectively, compared with the reference category (absence of sleep problems). Similarly, among females, the prevalence ratios were 1.32 (95% CI: 0.99–1.77) and 2.28 (95% CI: 1.74–3.00), respectively.

Conclusion This study demonstrated a strong association between sleep-related problems and minor psychiatric disorders in shift workers. Furthermore, the prevalence of minor psychiatric disorders and sleep-related problems were higher among females than males; however, the strengths of the association were higher in males.