Sleep disorders represent multifaceted pathophysiological conditions beyond simple sleep duration or quality disruptions. They are frequently associated with neuropsychiatric symptoms, cognitive decline, and systemic health deterioration. Among them, insomnia and obstructive sleep apnea (OSA) are highly prevalent and chronic, with established links to reduced quality of life and an increased risk of neurodegenerative diseases. This review summarized recent findings from neuroimaging studies that used quantitative cerebral blood flow (CBF) techniques, including arterial spin labeling (ASL) and single-photon emission computed tomography (SPECT), to examine functional brain changes associated with these disorders. Both insomnia and OSA consistently showed perfusion abnormalities in regions such as the prefrontal cortex, cingulate cortex, and hippocampus—areas that are critical for the sleep-arousal cycle, emotional regulation, and cognitive control. These alterations may reflect underlying mechanisms that include hemodynamic dysregulation, impaired metabolic regulation, and reduced connectivity in large-scale brain networks.Collectively, the evidence suggested that sleep disorders should be understood not merely as disturbances of sleep architecture, but as conditions involving cerebral hemodynamic dysregulation. Brain perfusion metrics thus hold clinical promise as sensitive biomarkers for early diagnosis, risk stratification, and treatment monitoring in sleep disorders and support the development of precision-guided interventions based on quantitative neuroimaging.

Objectives: This study is a retrospective chart review of outpatients who were prescribed prolonged-release melatonin at a university hospital in Korea between January 5, 2015, and January 20, 2020. Methods: Descriptive statistics were conducted for all prescription cases as well as by primary diagnosis. Differences according to sex, age, and final clinical improvement were also examined. In addition, separate analyses were performed for cases where prolonged-release melatonin was prescribed as monotherapy. Results: A total of 1,764 cases were analyzed. Prescriptions were more common in females, with a mean age of 66.24 years.The most frequent primary diagnosis was insomnia. At the initial visit, symptom severity ranged from mild to moderate, and at the final visit, patients were generally minimally improved. A total of 866 cases involved prolonged-release melatonin prescribed as monotherapy, with a higher proportion of male patients. The initial symptom severity in these cases was milder than that of the overall prescription cases. Conclusion These findings suggest the practical clinical utility of prolonged-release melatonin.

Objectives: Eveningness predominates in adolescence. Morningness has been reported to be associated with mental toughness via resilience. Morningness could be related to healthy sleep habits and a good personality. Methods: Sleep-related behaviors, such as weekend oversleep, social jetlag, and daytime sunlight exposure between 10:00 and 15:00, were evaluated using sleep-related questionnaires. Morningness-eveningness questionnaire, insomnia severity index, Epworth sleepiness scale, hospital anxiety and depression scale and defense style questionnaire were used. This study includes 1,610 high school students. Results: Multiple linear regression analysis revealed that morningness is predicted by male sex (β=0.115, t=4.769, p<0.001) and greater adaptive (β=0.092, t=3.506, p<0.001) and self-suppressive defense styles (β=0.072, t=2.192, p=0.029) and lesser immature defense styles (β=-0.163, t=-4.782, p<0.001) after controlling for age, sleep quality, depression, anxiety. Morningness is also predicted by greater sublimation (β=0.09, t=3.541, p<0.001) and reaction formation (β=0.112, t=4.488, p<0.001) and lesser consumption (β=-0.062, t=-2.501, p=0.012), passive aggression (β=-0.101, t=-3.747, p<0.001) and withdrawal (β=-0.084, t=-2.955, p=0.003), and male sex (β=0.117, t=4.896, p<0.001) after controlling for age, sleep quality, depression, and anxiety. Conclusion Morniness in adolescence may be related to a positive personality. Promoting morningness might be related to healthy development in personality.

Objectives: Both shift work and restless legs syndrome (RLS) are common and can disrupt sleep and mood. However, the effects of shift work on RLS remain unclear. The current study aims to explore the prevalence, severity, and related sleep and mood symptoms of RLS in shift workers (SWs) compared to non-shift workers (Non-SWs). Methods: This study recruited 4,562 SWs (age 36.98±9.84, 2,150 males and 2,422 females) and 2,093 NSWs (age 37.79±9.73, 999 males and 1,094 females). All participants completed online self-report questionnaires regarding RLS, sleep, and depression. The presence of RLS was screened using a single standard question for rapid screening of RLS. The severity of RLS was assessed using the International Restless Legs Syndrome Rating Scale (iRLS). Additionally, the Epworth Sleepiness Scale (ESS), Insomnia Severity Index (ISI), and short-term Center for Epidemiologic Studies Depression Scale (CES-D) were used to assess daytime sleepiness, insomnia, and depressive symptoms, respectively. Results: Of participants, 1,255 (27.45%) of SWs and 548 (26.18%) of Non-SWs were screened as having RLS, with no significant differences in the prevalence of RLS between the groups. However, among those with RLS, SWs with RLS showed higher iRLS scores compared to Non-SWs with RLS after controlling for age and sex (SWs: 9.55±7.26, NSWs: 6.75±6.05, F=64.15, p<0.01). In addition, SWs with RLS exhibited higher ISI scores (F=46.09, p<0.01), higher ESS scores (F=4.80, p=0.03), and higher CES-D scores (F=33.50, p<0.01) than Non-SWs with RLS. Conclusion Although there was no significant difference in RLS prevalence between SWs and Non-SWs, SWs with RLS exhibited more severe RLS symptoms and RLS-related symptoms, such as insomnia, sleepiness, and depression, compared to NSWs with RLS. The current study suggests that shift work may exacerbate RLS severity and RLS-related sleep and mood symptoms, although it may not be associated with the onset of RLS.

Public health and safety professionals, including firefighters, police officers, and emergency medical personnel, serve as critical pillars of public safety and societal well-being. These professions require navigating environments characterized by ‘brittleness’, ‘anxiety’, ‘nonlinearity’, and ‘incomprehensibility’—conditions that lead to chronic physical and psychological stress. This stress significantly elevates the risk of mental health disorders such as post-traumatic stress disorder, anxiety disorders, mood disorders, and sleep disturbances, while also increasing the likelihood of human errors driven by cognitive lapses. Such challenges extend beyond individual health, undermining organizational efficiency and ultimately jeopardizing public safety and societal welfare. Existing mental health management systems predominantly depend on reactive interventions, which are insufficient to meet the dynamic and unpredictable demands of high-risk occupational environments. As a proactive alternative, this paper introduces the concept of ‘Mind Vital Signs,’ an innovative framework that expands the traditional concept of vital signs into the mental health domain. Mind Vital Signs integrates physiological indicators—including heart rate variability, physical activity, respiratory rates, and sleep patterns—with psychological and behavioral data such as ecological momentary assessments and life logs. By employing real-time monitoring and advanced analytics, this multidimensional system facilitates early detection of mental health risks and supports targeted and timely preventive interventions. The implementation of Mind Vital Signs not only bolsters individual resilience and organizational stability but also enhances operational efficiency and strengthens public safety and societal well-being. Future research should prioritize clinical validation and policy development to ensure the effective integration and scalability of Mind Vital Signs in high-risk occupational settings.

Sleep is essential for physiological recovery and the maintenance of health. Over 15% of the population uses sleep medications and lacks access to effective cognitive-behavioral therapy for insomnia (CBT-I). CBT-I, which includes techniques such as sleep hygiene education, sleep diaries, relaxation techniques, stimulus control, and sleep restriction, is a standard treatment proven effective for chronic insomnia. This review aims to explain the significance of CBT-I techniques based on normal sleep regulation mechanisms. It discusses the principles of sleep hygiene education according to theories of circadian rhythms, homeostatic regulation, and conditioning. Furthermore, it examines zeitgebers such as light, melatonin, physical activity, diet, and social activities that regulate circadian rhythms, as well as habits that can disrupt these rhythms and how they can be effectively managed. The review explores how patients with insomnia can identify its causes, correct their habits, or seek professional help using wearable devices.

Sleep disorders are increasingly recognized as significant health issues in modern society, leading to decreased quality of life and increased socioeconomic costs. In this context, the integration of digital technology in sleep and chronobiology offers innovative approaches. This special issue introduces the latest research trends and prospects in digital healthcare applications in these fields. First, it presents strategies for utilizing digital technology to form healthy sleep habits based on normal sleep regulation mechanisms. Second, it analyzes the current status of research and development of digital therapeutics for insomnia both domestically and internationally, discussing their potential and challenges. Third, it explores the potential applications of circadian rhythm-based digital healthcare in the prevention and management of various diseases. These studies emphasize the importance of integrating chronobiological principles and digital technology in sleep medicine, presenting a new paradigm for personalized sleep management. However, the successful implementation of these innovative approaches requires multifaceted efforts, including interdisciplinary collaboration, technology development and standardization, validation of clinical effectiveness, and resolution of ethical and legal issues. Through this special issue, we aim to highlight the potential of chronobiology-based digital healthcare to contribute to the advancement of sleep medicine and the promotion of public health, while providing new insights for researchers and clinicians in this field.

Digital therapeutics have been at the center of increasing attention in the field of medicine over the past decade. In the field of sleep disorders, digital therapeutics for insomnia are the most actively developed, and have demonstrated their efficacy through clinical trials. Digital therapeutics for insomnia have been certified by regulatory or equivalent national body, including the United States and the United Kingdom, are being actively used in medical settings. In Korea, two digital therapeutics for insomnia received approval from the Ministry of Food and Drug Safety in the year of 2023. While the efficacy of digital therapeutics for insomnia proved their efficacy through clinical trials including real-world evidence, issues regarding adherence, digital literacy, cybersecurity, and integration into the healthcare industry need to be addressed.

The integration of chronobiology and digital healthcare is crucial for realizing personalized health management. This review examines the applications and possibilities of chronobiology-based digital healthcare in various medical fields. We confirm that the integration of chronobiology and digital technologies can provide a new paradigm in the prevention, diagnosis, and treatment of several diseases, including sleep disorders, mental disorders, cardiovascular diseases, and metabolic diseases. Circadian rhythm monitoring and intervention using digital technologies enable early detection and management of diseases and contribute to health promotion through personalized therapeutic interventions. Moreover, chronobiology-based digital healthcare has a high potential for application in various areas such as pharmacotherapy, occupational medicine, and sports medicine. To advance this convergence research, multidisciplinary collaboration, technology development and validation, and institutional support are necessary. In the future, chronobiology-based digital healthcare is expected to contribute to the realization of preventive, participatory, and patient-centered medicine.

Objectives: Eveningness predominates in adolescence. Morningness has been reported to be associated with mental toughness via resilience. Morningness could be related to healthy sleep habits and a good personality. Methods: Sleep-related behaviors, such as weekend oversleep, social jetlag, and daytime sunlight exposure between 10:00 and 15:00, were evaluated using sleep-related questionnaires. Morningness-eveningness questionnaire, insomnia severity index, Epworth sleepiness scale, hospital anxiety and depression scale and defense style questionnaire were used. This study includes 1,610 high school students. Results: Multiple linear regression analysis revealed that morningness is predicted by male sex (β=0.115, t=4.769, p<0.001) and greater adaptive (β=0.092, t=3.506, p<0.001) and self-suppressive defense styles (β=0.072, t=2.192, p=0.029) and lesser immature defense styles (β=-0.163, t=-4.782, p<0.001) after controlling for age, sleep quality, depression, anxiety. Morningness is also predicted by greater sublimation (β=0.09, t=3.541, p<0.001) and reaction formation (β=0.112, t=4.488, p<0.001) and lesser consumption (β=-0.062, t=-2.501, p=0.012), passive aggression (β=-0.101, t=-3.747, p<0.001) and withdrawal (β=-0.084, t=-2.955, p=0.003), and male sex (β=0.117, t=4.896, p<0.001) after controlling for age, sleep quality, depression, and anxiety. Conclusion Morniness in adolescence may be related to a positive personality. Promoting morningness might be related to healthy development in personality.