Sleep and Circadian Rhythms in Patients with Physical and Mental Disorders

Sleep and circadian rhythm disruptions are increasingly seen not just as secondary symptoms, but as active biological drivers and consequences of many physical and mental health conditions. This Special Issue consolidates current knowledge across sleep medicine, chronobiology, behavioral medicine, and clinical psychiatry to bridge theoretical gaps and map sleep dysregulation as a transdiagnostic mechanism. It synthesizes eight papers. A thorough description of the clinical profile of Long COVID insomnia was provided, demonstrating that this is a chronic, functionally significant condition that calls for proactive treatment rather than cautious waiting. The design of workplace mental health programs will be directly impacted by the discovery that occupational insomnia in healthcare workers is not just a result of workload but rather of a psychosocial cascade involving anger, cynicism, nightmare distress, burnout, and depression. Also, by taking into account both the intervention's content and its delivery context, we were able to advance our understanding of how digital CBT-I might be optimized, while the direct clinical discussion of thermoregulatory physiology and sleep disorders revealed a therapeutic dimension that is still largely unexplored in standard practice. The limited evidence supporting non-pharmacological treatment of narcolepsy was highlighted, while bruxism-related parasomnia was placed within a broader context related to sleep health. Furthermore, eating disorder susceptibility was added to the scope of circadian medicine, proving that chronotype has psychological effects that go far beyond mood and sleep.