Sleep Architecture, Cognitive Function, and Quality of Life During Early Recovery From Substance Use Disorder

This prospective cohort study investigates how sleep disturbances affect cognitive recovery and quality of life during early recovery from substance use disorder (SUD). Chronic substance use frequently alters normal sleep architecture, which may impair attention, memory, and everyday functioning. The primary aim is to characterize baseline sleep patterns in adults with SUD compared to healthy control participants and determine whether baseline sleep disruptions predict cognitive and functional recovery over three months of monitored abstinence. The study includes two groups of participants aged 18 to 45 years: adults diagnosed with a primary substance use disorder undergoing treatment and monitored abstinence, and a comparison group of healthy volunteers matched for age, sex, education, work schedule, and caffeine or nicotine use. At the beginning of the study, all participants complete: * Structured diagnostic interviews and clinical assessments for mood, anxiety, and attention. * Questionnaires evaluating subjective sleep quality (Pittsburgh Sleep Quality Index) and quality of life (WHOQOL-BREF). * A global cognitive screening test (Montreal Cognitive Assessment) and a computerized attention test (Continuous Performance Task). * An overnight sleep study (polysomnography) conducted in a sleep laboratory following an initial adaptation night to objectively record brain waves, sleep stages, oxygen levels, and sleep continuity. Participants in the substance use disorder group undergo supervised abstinence monitoring via periodic clinical check-ins and random urine drug screens. At 1 month and 3 months post-baseline, participants repeat the cognitive tests, quality-of-life questionnaires, and mood/sleep assessments to track recovery trajectories over time (no repeat overnight sleep studies are performed).

Inclusion Criteria: Substance Use Disorder (SUD) Cohort: * Age between 18 and 45 years. * Fulfillment of DSM-5 diagnostic criteria for a primary Substance Use Disorder. * Admitted to inpatient wards or followed in outpatient neuropsychiatry services. * Resolution of acute intoxication and clinically significant withdrawal prior to sleep assessment. * Availability and willingness to complete baseline evaluations and prospective 1-month and 3-month follow-up assessments. Matched Control Cohort: * Age between 18 and 45 years. * Absence of current or lifetime Substance Use Disorder. * Matched to the SUD cohort by age, sex, education level, shift-work status, and caffeine/nicotine use. * Availability and willingness to complete baseline and follow-up assessments. Exclusion Criteria: * Primary major independent psychiatric disorders predating the onset of substance use (e.g., schizophrenia, bipolar disorder). * Pre-existing primary sleep disorders independent of substance use (e.g., previously diagnosed severe obstructive sleep apnea, narcolepsy). * Current intake of prescription medications known to severely alter sleep architecture or cognitive function (e.g., chronic benzodiazepines, high-dose antipsychotics, antiepileptics). * History of severe traumatic brain injury, neurological illness, or structural brain lesions. * Acute psychiatric instability requiring urgent emergency clinical intervention. * Impaired capacity to provide informed consent or conditions preventing valid completion of sleep studies or cognitive testing. * Refusal to participate or withdrawal of consent.