Ingo Fietze

The aim of the study was to test the applicability of the action spectrum of melatonin suppression (MS) based on monochromatic experimental data from Brainard et al. ( Journal of Neuroscience , 2001, 21, 6405) and Thapan et al. ( Journal of Physiology , 2001, 535, 261) to quantify MS using white light and to characterize its temporal course during the first hour of exposure. Using a within‐subject design, 32 healthy adults (12 males/20 females) with free pupil adaptation were exposed to white light of 1904–6996 K in correlated color temperature (CCT), and to blue light (BL, 474 nm). Two “circadian effective” irradiances ( E _c = 0.264 W m ⁻² and 0.528 W m ⁻² ) based on Gall's metric ( Licht , 2002, 54, 1292) were applied for 60 min using ganzfeld devices. Melatonin concentrations were measured in blood plasma. For 25 participants with complete data sets at E _c = 0.264 W m ⁻² , the r‐ANOVA indicated a significant difference in MS between the five different light spectra, F (4,96) = 4.97, p = 0.011. The Bonferroni‐corrected post hoc paired t‐test (α = 0.005) showed significantly lower melatonin reduction by BL than white light of 2883 K and 1904 K, but not vs. 6997 K and 4663 K. This was due to an unexpectedly high proportion of 11 subjects (=44%) who did not respond to BL with MS (“BL non‐responders”). For 14 subjects (“BL responders”, =56%), r‐ANOVA confirmed equivalent values of MS under all five lighting conditions at both irradiances. Additivity of spectral contributions to the circadian effectiveness of white light is limited, as is reciprocity only with respect to cold white light.

Obstructive sleep apnea (OSA) and smoking are both prevalent and impactful health risks. While smoking may contribute to OSA through inflammatory and neuromuscular pathways, population-based evidence on this relationship remains limited and inconsistent. A sample ( N = 1,206) from the population-based Study of Health in Pomerania with complete overnight polysomnography and smoking assessment was investigated in a cross-sectional study for an association between OSA and former as well as recent smoking status. Regression models adjusted for Age and BMI were applied. Current smoking was significantly associated with increased apnea-hypopnea-index (AHI) severity (OR = 1.75, 95% CI [1.27; 2.41], p < .001), with stratified analyses confirming the effect across younger and older participants. Former smokers also showed significantly elevated AHI severity compared to never-smokers (OR = 1.76, 95% CI [1.27; 2.43], p < .001). Both current and former smoking were significantly associated with greater OSA severity in this population-based sample, even after accounting for age and BMI. The findings underscore the long-term respiratory consequences of smoking and highlight the need for integrated approaches in smoking cessation and OSA screening.

Introduction: Insufficient or disturbed sleep impairs nocturnal physiological recovery and may negatively affect autonomic nervous system (ANS) regulation. Astronauts are a particularly vulnerable group due to sustained workloads, isolation, and exposure to extreme operational conditions. The present study investigated the interaction between sleep structure and ANS state under different sleep conditions during a prolonged space analogue mission (SAM) conducted as part of the Scientific International Research in a Unique Terrestrial Station (SIRIUS-19) project. Methods: Six healthy participants (three men and three women; age: 34.3 ± 5.7 years) were studied over eight nights during the four-month SIRIUS-19 mission: one night of undisturbed sleep pre-isolation, one night of undisturbed sleep post-isolation, and six nights during the isolation phase comprising three undisturbed nights, one night of complete sleep deprivation, and two nights of experimentally induced sleep fragmentation (repeated short awakenings vs. one prolonged awakening). Sleep structure and ANS state were assessed using a portable, self-applicable, medical-grade sleep recording system that captured electroencephalography (EEG), electrooculography (EOG), electrocardiogram (ECG), and plethysmography signals. Results: Significant differences in total sleep time were observed across different nights ( p = 0.003). On nights of undisturbed isolation, participants achieved more than 7 h of sleep, while nights with sleep fragmentation was associated with reduced sleep efficiency (p < 0.0001) and the heart rate variability (HRV) LF/HF ratio ( p < 0.005), with the most pronounced autonomic activation occurring during the night of complete sleep deprivation. Discussion: Using a portable monitoring approach, this study demonstrates that nocturnal ANS regulation during prolonged isolation is relatively resilient to moderate sleep fragmentation, but is markedly affected by sustained sleep loss. These findings highlight the importance of preserving restorative sleep continuity when planning operationally demanding space missions and support the feasibility of portable sleep and ANS monitoring in extreme environments.

Zusammenfassung Die Insomnie, insbesondere die chronische Insomnie, ist eine häufige Erkrankung, die auch in der neuen Internationalen statistischen Klassifikation der Krankheiten und verwandter Gesundheitsprobleme (ICD-11) als eigenständiges Krankheitsbild ausgewiesen ist. Die Diagnose einer chronischen Insomnie basiert auf der Eigen- und Fremdanamnese, auf Fragebögen zur Schlaf- und Lebensqualität, einem Schlaf-Wach-Protokoll und bei Bedarf einer Messung der Schlafqualität. Zusätzlich sind andere den Schlaf störende Faktoren und andere Schlaferkrankungen auszuschließen, gegebenenfalls auch im Schlaflabor. Präventiv und als erster Therapieschritt sollte die kognitive Verhaltenstherapie zur Anwendung kommen. Ein strukturiertes flächendeckendes Angebot fehlt jedoch. Daher können auch digitale Angebote genutzt werden. Bei moderater bis schwerer Insomnie ist häufig die Behandlung mit schlaffördernden Medikamenten erforderlich, was auch in den Leitlinien verankert ist. Hier fehlen jedoch strukturierte individualisierte Behandlungspfade. Wir empfehlen eine Stufentherapie, zunächst mit leicht schlaffördernden Mitteln wie Melatonin bis hin zu den Hypnotika wie Daridorexant. Eine medikamentöse Therapie ist erfolgreich, wenn sie gezielt und ärztlich begleitet angewendet wird. Da die Versorgungssituation für Betroffene von Insomnie mangelhaft ist, braucht es mehr Aufklärung für Betroffene und die Ärzteschaft, zudem ein Zusammenspiel von Hausärzten, Allgemeinmedizinern, Fachärzten und Schlafmedizinern.

Sleep medicine centres play a pivotal role in diagnosing, treating and researching sleep disorders, with structures that range from large, university‐based institutions to smaller, community‐led clinics. These centres operate at the intersection of clinical care and academic innovation, combining personalised diagnostics and therapy with the evaluation and integration of emerging technologies. As the demand for sleep‐related healthcare continues to grow, sleep centres must evolve to accommodate both increasing patient loads and rapid technological advancements. Outpatient departments serve as critical entry points for patients, enabling structured assessments through consultations, questionnaires and objective tools such as actigraphy and home polygraphy. These are increasingly complemented by digital solutions, including telemedicine, automated sleep diaries and remote prescription management. Such tools improve accessibility, streamline workflows and enhance continuity of care. Despite technological progress, sleep laboratories remain indispensable for diagnosing complex disorders like sleep apnea and hypersomnias, where in‐lab polysomnography and real‐time therapy adjustments are essential. However, advances in portable and wearable devices are creating viable home‐based alternatives for selected cases, contributing to reduced lab wait times and broader patient reach. Research and education are foundational to advancing the field. Ongoing updates to sleep medicine curricula, alongside rigorous clinical studies on novel diagnostics and AI tools, ensure that care remains evidence‐based and future‐ready. Sleep centres, as multidisciplinary hubs, will continue to merge clinical practice, innovation and training—shaping a future where sleep healthcare is more personalised, data‐driven and accessible without compromising quality or equity. Together, these developments signal a transformative era in sleep medicine, where integrated, technology‐enhanced care will redefine how we understand, diagnose and treat sleep disorders.

Background: This study examines the relationship between obstructive sleep apnea severity, sleep position, and body weight, particularly focusing on the negative impact of sleeping in a supine position combined with being overweight in a population-based sample. Methods: The Apnea-Hypopnea Index (AHI) was utilized as a marker of OSA severity and sleep position from a standardized overnight polysomnography. Participants were categorized by body mass index (BMI) (kg/m²) into normal weight/underweight (<25) and overweight (≥25). Results and Conclusions: The results indicated a higher mean Apnea-Hypopnea Index for those sleeping in the supine position compared to other positions, with overweight individuals experiencing a proportionally greater impact from sleep position than their normal-weight counterparts.