Circadian rhythm

Chronobiology studies indicate that individuals are regulated by three timers: social, solar, and biological. Environmental and behavioral changes can modify the sleep–wake cycle. Many university students adopt nighttime study habits, interfering with the circadian rhythm. Sleep restriction or poor sleep quality compromises memory and significantly reduces academic performance. This study aimed to verify whether there is an association between sleep quality and academic performance among nursing and medical students at a public university in Alagoas, Brazil. This is an observational, cross-sectional, and quantitative study conducted with 137 Nursing and Medical students, selected through stratified probabilistic sampling. Data collection included a sociodemographic questionnaire to characterize the sample, the Pittsburgh Sleep Quality Index (PSQI), the Munich Chronotype Questionnaire (MCTQ), and academic self-assessment. Data were analyzed for normality, and associations were tested using Pearson and Spearman correlations (SciPy – Python). Among the 137 students, 65.7% were women, 70.1% were between 19 and 24 years old, 67.9% rated their academic performance between 7.0 and 8.9, and 66.4% presented poor sleep quality. Negative correlations between the PSQI and self-assessment variables (r = -0.368; p < 0.001 for Pearson; r = -0.360; p < 0.001 for Spearman) reinforce the importance of sleep quality in the academic context. The findings highlight the urgency of interventions that promote sleep hygiene education and strategies to improve rest quality, reducing the likelihood of problems that may negatively impact students’ academic performance.

Sleep and circadian disturbances in Alzheimer’s disease (AD) affect patients and caregivers, but clinical action depends on the syndrome, measurement, and outcome under consideration. This narrative review links sleep assessment to indication-based care while distinguishing symptomatic benefit, physiological target engagement, and disease modification. A purposive literature search was supplemented by targeted checks of PubMed-indexed and original publisher records through 4 October 2026. Selected studies are described by population, AD ascertainment, comparator, and measured endpoint rather than assigned formal evidence-certainty grades. Actigraphy characterizes behavioral rest–activity patterns; melatonin timing and temperature rhythms address endogenous circadian physiology under controlled conditions. Polysomnography and quantitative electroencephalography characterize respiratory events, sleep architecture, and oscillatory activity. These measurements inform different questions and do not independently assign AD etiology or cognitive-functional stage. Clinical priorities include confirmed obstructive sleep apnea, cognition-adapted insomnia care, irregular sleep timing, medication-related effects, parasomnias, limb symptoms, and excessive daytime sleepiness. Interpretation incorporates hypoxemia, treatment exposure, comorbidity, caregiver support, and competing diagnoses. Randomized sleep benefits remain distinct from observational cognitive associations or exploratory imaging and cerebrospinal fluid changes. Human and animal studies of arousal circuits, protein dynamics, inflammation, and fluid transport provide mechanistic context, with conflicting results interpreted according to the actual experimental endpoint. The review provides a clinically organized account of selected evidence, not a comprehensive treatment ranking. Sleep care and cognitive-etiologic assessment should proceed in parallel, with follow-up matched to patient function, safety, and the specific treatment goal.

Few events in recent history have forced clinicians and researchers to rethink mental health quite like COVID-19. In this commentary, we reflect on something that struck us while reading the work of Cantone et al. : the pandemic, for all its devastation, created a kind of unplanned observational window, a chance to study, at population scale, what happens when stress and rhythm disruption hit at the same time. Healthcare Workers (HCWs) were at the epicentre of this. They didn't just witness the crisis; they absorbed it, shift after shift, for months. What the data show is that their depressive symptoms and rhythm instability were not random; they appear systematically linked, and at levels one would more typically associate with mood disorder research. We discuss these findings through the lens of DYMERS (Dysregulation of Mood, Energy, and Social Rhythms Syndrome), a heuristic transdiagnostic construct that, in our view, captures something that standard categorical diagnoses tend to miss: the subthreshold, fluctuating psychopathology that sits just below the threshold of formal diagnosis but causes real impairment. The pandemic may not have created these vulnerabilities, but it may well have sharpened our ability to see them.

This study investigated the extent to which number of psychiatric disorders and specific comorbidities in patients receiving the Transdiagnostic Intervention for Sleep and Circadian Dysfunction (TSC) predicted symptom/impairment severity and treatment outcome. This secondary analysis drew from a subset of 489 patients in Community Mental Health Centers (CMHCs) with serious mental illness (SMI) and sleep/circadian problems who had participated in a randomized controlled trial of TSC. Of these patients, 253 received Immediate TSC and 236 received usual care followed by delayed treatment (UC-DT). Some patients received Standard TSC (N = 149) while others received Adapted TSC (N = 340). Patients' baseline/pre-treatment and post-treatment scores for psychiatric symptoms, sleep disturbance, sleep-related impairment, overall sleep health, and functional impairment were analyzed. Patient-reported data on history of psychiatric diagnoses were also used. At baseline, patients with more disorders had significantly worse psychiatric symptom scores (b = 2.27, SE = 0.39, p<.001), marginally greater sleep disturbance (b = 0.57, SE = 0.32, p=.073) (but only at the nominal level), significantly greater sleep-related impairment (b = 1.25, SE = 0.34, p<.001), significantly worse overall sleep health (b=-0.20, SE = 0.06, p=.001), and significantly greater functional impairment (b = 0.32, SE = 0.11, p=.005). Number of psychiatric disorders was not associated with treatment outcome or differences in benefits between Standard and Adapted TSC. When analyzed independently, the most common psychiatric disorder groups all demonstrated significantly more improvement in the Immediate TSC group than in the UC-DT group on sleep disturbance and sleep-related impairment. These results build on strong evidence that transdiagnostic sleep treatment is an important approach to treating populations with comorbid SMI and sleep/circadian problems.

این مطالعه به بررسی میزان تأثیر تعداد اختلالات روان‌پزشکی و هم‌ابتلایی‌های خاص در بیماران دریافت‌کننده‌ی مداخله‌ی فراتشخیصی برای اختلال خواب و ریتم شبانه‌روزی (TSC) بر شدت نشانه‌ها/ناتوانی و پیامد درمان پرداخت. این تحلیل ثانویه از زیرمجموعه‌ای از ۴۸۹ بیمار در مراکز سلامت روان جامعه (CMHCs) با بیماری روانی شدید (SMI) و مشکلات خواب/ریتم شبانه‌روزی که در کارآزمایی تصادفی‌شده‌ی کنترل‌شده‌ی TSC شرکت کرده بودند، استفاده کرد. از میان این بیماران، ۲۵۳ نفر TSC فوری دریافت کردند و ۲۳۶ نفر مراقبت معمول به‌دنبال درمان با تأخیر (UC-DT) دریافت کردند. برخی بیماران TSC استاندارد (N = 149) و برخی دیگر TSC تطبیق‌یافته (N = 340) دریافت کردند. نمرات بیماران در آغاز/پیش از درمان و پس از درمان برای نشانه‌های روان‌پزشکی، اختلال خواب، ناتوانی مرتبط با خواب، سلامت کلی خواب و ناتوانی عملکردی تحلیل شد. همچنین داده‌های خودگزارش‌شده‌ی بیماران درباره‌ی سابقه‌ی تشخیص‌های روان‌پزشکی مورد استفاده قرار گرفت. در آغاز مطالعه، بیماران با اختلالات بیشتر به‌طور معناداری نمرات نشانه‌های روان‌پزشکی بدتری داشتند (b = 2.27, SE = 0.39, p<.001)، اختلال خواب به‌طور حاشیه‌ای بیشتر (b = 0.57, SE = 0.32, p=.073) (اما فقط در سطح اسمی)، ناتوانی مرتبط با خواب به‌طور معناداری بیشتر (b = 1.25, SE = 0.34, p<.001)، سلامت کلی خواب به‌طور معناداری بدتر (b=-0.20, SE = 0.06, p=.001)، و ناتوانی عملکردی به‌طور معناداری بیشتر (b = 0.32, SE = 0.11, p=.005) داشتند. تعداد اختلالات روان‌پزشکی با پیامد درمان یا تفاوت در منافع بین TSC استاندارد و تطبیق‌یافته ارتباطی نداشت. در تحلیل مستقل، همه‌ی گروه‌های شایع اختلالات روان‌پزشکی در گروه TSC فوری نسبت به گروه UC-DT در اختلال خواب و ناتوانی مرتبط با خواب بهبود معنادار بیشتری نشان دادند. این نتایج بر شواهد قوی مبنی بر این‌که درمان فراتشخیصی خواب رویکردی مهم برای درمان جمعیت‌های مبتلا به SMI همراه با مشکلات خواب/ریتم شبانه‌روزی است، می‌افزاید.

Mood follows a well-documented circadian rhythm. Sleep timing and duration are similarly shaped by biological and social factors. However, large-scale, real-world data on how these patterns vary across demographic groups remain limited. Prior studies often rely on laboratory data or social media linguistic analysis, which lack direct self-reports. This study examines hourly, weekly, and demographic trends in mood and sleep duration reports using one of the largest online datasets of directly self-reported behavioral health: 468,092 Lumosity users (aged 20–79) who reported daily mood (−2 to +2 scale) and sleep duration (≤5–9 + hours). We assessed variation by time of day, day of week, and interactions of age, gender, and race/ethnicity using ANOVA and linear regression. Mood was higher among users reporting in the afternoon and evening, and lower from late night through morning. Mood showed a U-shaped pattern with age, consistent throughout the week, and longer sleep duration was linked to better mood reports throughout the day and week. Sleep duration varied by time of report and by day of week, with longer durations in the afternoon/evening and on weekends. Women reported longer sleep overall, Black users reported shorter sleep, and sleep duration declined from young adulthood through midlife before rising slightly among older users. Higher mood was associated with longer sleep, and the weekday-weekend mood difference was larger among users reporting longer sleep. These findings demonstrate the value of large-scale digital data for public health insight, highlighting demographic disparities in sleep and the importance of midlife as a key intervention period. Because the sample is likely skewed toward higher educational attainment and health engagement, disparity estimates may understate true population-level differences. The late-night peak in negative affect aligns with literature on nocturnal suicide risk, though this nonclinical sample cannot directly speak to clinical risk or crisis-service need.

خلق و خو از یک ریتم شبانه‌روزی مستند پیروی می‌کند. زمان‌بندی و مدت خواب نیز به طور مشابه تحت تأثیر عوامل زیستی و اجتماعی قرار دارند. با این حال، داده‌های واقعی و گسترده درباره چگونگی تغییر این الگوها در میان گروه‌های جمعیت‌شناختی همچنان محدود است. مطالعات پیشین اغلب به داده‌های آزمایشگاهی یا تحلیل زبانی شبکه‌های اجتماعی متکی هستند که فاقد خودگزارش‌دهی مستقیم می‌باشند. این مطالعه روندهای ساعتی، هفتگی و جمعیت‌شناختی در گزارش‌های خلق و مدت خواب را با استفاده از یکی از بزرگ‌ترین مجموعه داده‌های آنلاین سلامت رفتاری با خودگزارش‌دهی مستقیم بررسی می‌کند: ۴۶۸٬۰۹۲ کاربر Lumosity (در بازه سنی ۲۰ تا ۷۹ سال) که روزانه خلق (در مقیاس −۲ تا +۲) و مدت خواب (۵ ساعت یا کمتر تا ۹ ساعت و بیشتر) را گزارش کردند. ما تغییرات را بر اساس زمان روز، روز هفته و تعاملات سن، جنسیت و نژاد/قومیت با استفاده از تحلیل واریانس (ANOVA) و رگرسیون خطی ارزیابی کردیم. خلق در میان کاربرانی که در بعدازظهر و عصر گزارش داده‌اند بالاتر و از نیمه‌شب تا صبح پایین‌تر بود. خلق الگوی U شکلی با سن نشان داد که در طول هفته ثابت بود و مدت خواب طولانی‌تر با گزارش‌های خلق بهتر در سراسر روز و هفته همراه بود. مدت خواب بر اساس زمان گزارش و روز هفته متفاوت بود، به طوری که در بعدازظهر/عصر و آخر هفته‌ها مدت خواب طولانی‌تر بود. زنان به طور کلی خواب طولانی‌تری گزارش کردند، کاربران سیاه‌پوست خواب کوتاه‌تری گزارش کردند و مدت خواب از اوایل بزرگسالی تا میانسالی کاهش یافت و سپس در میان کاربران مسن‌تر اندکی افزایش یافت. خلق بالاتر با خواب طولانی‌تر همراه بود و تفاوت خلق بین روزهای هفته و آخر هفته در میان کاربرانی که خواب طولانی‌تری گزارش کردند بیشتر بود. این یافته‌ها ارزش داده‌های دیجیتال گسترده را برای بینش سلامت عمومی نشان می‌دهد و بر نابرابری‌های جمعیت‌شناختی در خواب و اهمیت میانسالی به عنوان دوره‌ای کلیدی برای مداخله تأکید می‌کند. از آنجا که نمونه احتمالاً به سمت تحصیلات بالاتر و مشارکت بیشتر در سلامت گرایش دارد، برآورد نابرابری‌ها ممکن است تفاوت‌های واقعی در سطح جمعیت را کمتر از واقعیت نشان دهد. اوج خلق منفی در نیمه‌شب با ادبیات مربوط به خطر خودکشی شبانه همسو است، اگرچه این نمونه غیر بالینی نمی‌تواند مستقیماً درباره خطر بالینی یا نیاز به خدمات بحران اظهار نظر کند.