The article reviews the reciprocal relationship between sleep, circadian rhythms, and mental health, highlighting how disruptions in sleep quality, continuity, and timing can exacerbate or precipitate psychiatric symptoms, and vice versa. It emphasizes the need for a cohesive approach that integrates the dynamic interactions between psychiatric disorders and sleep and circadian processes. The review focuses on adolescent and young adults, who are at high risk of developing mental disorders, and discusses the importance of early detection and intervention. Key points include: 1. **Sleep-Circadian Dysfunction as a Transdiagnostic Contributor**: Sleep and circadian disturbances are common across various psychiatric disorders, including mood, anxiety, and psychotic disorders. These disturbances can lead to relapse and worsen symptoms. 2. **Biological Mechanisms**: The article explores the biological mechanisms underlying sleep-circadian dysfunction, such as the role of clock genes, light exposure, and circadian misalignment. It also discusses the impact of sleep on neuroplasticity and emotional regulation. 3. **Intervention Studies**: Intervention studies have shown that targeting sleep-circadian disturbances can improve comorbid psychiatric symptoms. However, these interventions are not yet widely adopted in clinical practice. 4. **Future Directions**: The review calls for a coordinated research agenda to better understand the differential expression of sleep-circadian dysfunction in different psychiatric phenotypes and to identify critical windows of vulnerability for preventative interventions. 5. **Technological Advancements**: The use of remote sleep-sensing technologies and improved automated sleep scoring algorithms is highlighted as a promising tool for real-time sleep analysis and closed-loop neurostimulation paradigms. Overall, the article underscores the importance of integrating sleep and circadian science into psychiatry to improve the understanding and treatment of mental disorders.The article reviews the reciprocal relationship between sleep, circadian rhythms, and mental health, highlighting how disruptions in sleep quality, continuity, and timing can exacerbate or precipitate psychiatric symptoms, and vice versa. It emphasizes the need for a cohesive approach that integrates the dynamic interactions between psychiatric disorders and sleep and circadian processes. The review focuses on adolescent and young adults, who are at high risk of developing mental disorders, and discusses the importance of early detection and intervention. Key points include: 1. **Sleep-Circadian Dysfunction as a Transdiagnostic Contributor**: Sleep and circadian disturbances are common across various psychiatric disorders, including mood, anxiety, and psychotic disorders. These disturbances can lead to relapse and worsen symptoms. 2. **Biological Mechanisms**: The article explores the biological mechanisms underlying sleep-circadian dysfunction, such as the role of clock genes, light exposure, and circadian misalignment. It also discusses the impact of sleep on neuroplasticity and emotional regulation. 3. **Intervention Studies**: Intervention studies have shown that targeting sleep-circadian disturbances can improve comorbid psychiatric symptoms. However, these interventions are not yet widely adopted in clinical practice. 4. **Future Directions**: The review calls for a coordinated research agenda to better understand the differential expression of sleep-circadian dysfunction in different psychiatric phenotypes and to identify critical windows of vulnerability for preventative interventions. 5. **Technological Advancements**: The use of remote sleep-sensing technologies and improved automated sleep scoring algorithms is highlighted as a promising tool for real-time sleep analysis and closed-loop neurostimulation paradigms. Overall, the article underscores the importance of integrating sleep and circadian science into psychiatry to improve the understanding and treatment of mental disorders.