BACKGROUND: Survivors of critical illness endure long-lasting physical and mental challenges. Despite the persistence of poor sleep quality in a considerable proportion of patients at the 12-month follow-up, studies with assessments exceeding this period are limited. We aimed to investigate the trajectory of sleep over the 24 months following critical illness. METHODS: Observational, prospective study. Patients diagnosed with SARS-CoV-2 infection were recruited during the intensive care unit stay. Evaluations of sleep (Pittsburgh Sleep Quality Index [PSQI]), mental health (Hospital Anxiety and Depression Scale [HADS]), quality of life (12-item Short Form Survey [SF-12]), and other factors were performed in the short-term, and at 12 and 24 months after hospital discharge. Good sleep quality was defined as a PSQI score of ≤ 5. Minimal clinically important improvement (MCII) was defined as a decrease of ≥ 4 points in the PSQI score between the short-term assessment and the 24-month follow-up. RESULTS: The cohort included 196 patients (69.9% males), with a median [p CONCLUSIONS: Our findings reveal that a subset of critical illness survivors requires up to 24 months after the acute phase to fully restore their sleep quality, while a significant proportion does not experience a clinically significant improvement in sleep quality over this period. These distinct sleep trajectories are strongly correlated with mental health status, highlighting the importance of addressing sleep alongside mental health within the framework of post-intensive care syndrome.