There is already scientific evidence demonstrating a strong relationship between sleep quality and mental disorders. Firefighters are professionals who are more susceptible to these disturbances due to the nature of their work and shift schedules. This study aims to assess the subjective sleep quality and the levels of anxiety, depression, and stress in a sample of Portuguese volunteer firefighters. The Pittsburgh Sleep Quality Index (PSQI), validated for the Portuguese population, and the Anxiety, Depression, and Stress Scale (ADSS) were applied to a sample of 66 Portuguese volunteer firefighters. The results showed that 24 individuals have poor sleep quality and high levels of anxiety and stress. A strong correlation between anxiety levels and poor sleep quality is confirmed (p-value 0.02; ρ=0.31). However, it is known that years of experience as a firefighter are not related to the decrease in sleep quality and the levels of anxiety, depression, and stress. Given the high-risk nature of the activity and potential exposure to different psychological traumas, the adoption of psychological support measures for volunteer firefighters is necessary.