OBJECTIVES: Chronic use of benzodiazepines and z-drugs (BZD/Zs), the most commonly used symptomatic treatment for sleep problems, is discouraged because of the unproven long-term effectiveness. In this study, we evaluated 1-year evolution of subjective sleep quality of chronic BZD/Z users compared with nonusers. METHODS: All cognitively competent residents from ten Belgian nursing homes were screened and compiled in a group of chronic BZD/Z users or nonusers, based on the medication chart. We collected demographic, functional and psychometric characteristics (depressive symptoms with the 8-item Geriatric Depression Scale), sleep parameters (with the Pittsburgh Sleep Quality Index-PSQI) and medication use. We analysed evolution of sleep quality with nonparametric statistics. Associations with worsening of sleep quality were analysed with linear regression. RESULTS: We collected data of 131 BZD/Z users and 95 nonusers. The mean age in both groups was 85 years and 77 % was female. Over a period of 1 year, the PSQI score evolved from 5.2 to 5.8 (p = 0.035) in the BZD/Z users, and from 4.3 to 4.7 (p = 0.078) in the nonusers. Though the mean deterioration in 1 year did not differ significantly between both groups, the BZD/Z users had a significantly worse sleep quality compared with nonusers at both time points. Depressive symptoms were significantly associated with worsening sleep quality (β = -0.243, p < 0.001). CONCLUSION: Sleep quality in chronic BZD/Z users significantly decreased over 1 year and was significantly worse than in nonusers at the end of this period. This study suggests that using BZD/Zs chronically does not maintain or improve sleep quality. Depressive symptoms are an important factor in the deterioration of sleep quality.