Purpose The study aimed to understand the relationship between intraocular pressure (IOP) and central corneal thickness (CCT) in older adults living in North Karnataka and the diurnal variation of IOP in the elderly population. Methods This is a population-based cross-sectional study in which 84 eyes of 42 study participants aged over 50 years were examined. A complete ophthalmic examination was done for all subjects. IOP was measured with an iCare IC100 (Icare Finland Oy, Vantaa, Finland) rebound tonometer and CCT with an ultrasound pachymeter. Statistical significance was accepted as p<0.05. Results The mean age of the study participants was 64.42±6.917 years. The mean IOP and CCT at 1 pm were 12.4±2.576 and 509.24±25.379 in the right eye, and 12.45±2.319 and 511.05±24.464 in the left eye. Spearman\'s correlation showed that IOP was positively correlated with CCT, with p<0.05. This showed that CCT has the most significant impact on IOP. In our study, the diurnal variation of IOP by paired samples t-test was also crucial in the elderly population, with p<0.05. Conclusion In this study, IOP was reduced as the CCT was reduced, and vice versa, i.e., IOP was positively correlated with CCT. The diurnal variation of IOP in older people was the same as in the young and middle-aged population, i.e., the highest recording of IOP was in the morning, and it gradually reduced as the day passed.

While previous studies have explored a range of factors governing the optimal use of caffeine (CAF) in athletes, limited research has explored how time of day (TOD) affects the ergogenic effects of various CAF dosages on physical performance. This study aimed to increase knowledge about how different recommended CAF doses (3 mg/kg vs. 6 mg/kg) ingested at different TODs affected maximal high-intensity physical performance and the perception of potential side effects in female athletes. In this double-blind, randomized, and counterbalanced study, 15 low CAF consumer athletes (aged 18.3 ± 0.5 y) underwent six trials, including three testing conditions assessed across two TODs: one in the morning (08:00 a.m.) and one in the evening (06:00 p.m.). During each condition, the participants ingested either a placebo, 3 mg/kg CAF (CAF (3 mg)), or 6 mg/kg CAF (CAF (6 mg)) capsules 60 min before each test with an in-between washout period of at least 72 h. In each trial, the participants performed a countermovement jumps test (CMJ), a modified agility t test (MATT), a repeated sprint ability (RSA), a rating of perceived exertion (RPE), and finally, a CAF side effects questionnaire. Our findings indicate the absence of an ergogenic effect on CMJ, MAT, and RSA performance in the evening after administering CAF (3 mg) or CAF (6 mg) compared to a placebo. Likewise, when CAF was ingested in the morning, there was an improvement in these performances with both CAF (3 mg) and CAF (6 mg), with greater improvement observed after CAF (6 mg). Additionally, neither the CAF dosage nor the TOD had a significant effect on the RPE. The occurrence of side effects increased significantly after the evening ingestion of CAF, particularly with a moderate dose of CAF (6 mg). Our findings indicate that the effectiveness of CAF depends on the TOD and CAF dosage. When ingested in the morning, a moderate dose of CAF (6 mg), rather than CAF (3 mg), is more effective in improving short-term physical performance without affecting CAF side effects in female athletes. Nevertheless, when ingested in the evening, neither dose was sufficient to enhance short-term physical performance, and both dosages increased the incidence of CAF side effects, particularly at a moderate dose.

BACKGROUND: Heart rate variability (HRV) may provide objective information about cardiogenic autonomic balance in individuals with spinal cord injury (SCI). The aim of this study was to characterize the diurnal variation of HRV in individuals with SCI at lesion level T6 and above and lesion level below T6.
METHODS: This was a retrospective analysis of a prior cross-sectional study. Individuals with chronic SCI underwent 24 h recording of the time between consecutive R waves (RR interval) to derive parameters of HRV as follows: standard deviation of all normal-to-normal R-R intervals (SDNN) and square root of the mean of the squared differences between successive R-R intervals (RMSSD) (time domain); and high frequency power (HF), low-frequency power (LF), very low frequency power (VLF), ultra-low frequency power (ULF) and total power (TP) (frequency domain). Changes in the magnitude of HRV outcomes over the 24 h period were investigated using a novel multi-component cosinor model constrained to the form of a three-harmonic Fourier series.
RESULTS: Participants were grouped as lesion level T6 and above (n = 22) or below T6 (n = 36). Most of them were male (n = 40, 69%) and the median age (interquartile range) was 50.5 (28) years. Both groups exhibited similar diurnal patterns in most HRV metrics. The lowest values occurred in the late afternoon (4-6 pm) and gradually increased, peaking around midnight to early morning (1-6 am). Exceptions included RMSSD, which peaked before midnight, and ULF, which showed a double peak pattern that peaked from 11 am to 1 pm and 4-6 am in participants with lesion level at T6 and above. The HRV values in participants with lesion level T6 and above were generally lower than participants with lesion level below T6, except for peak values of RMSSD, HF and LF.
CONCLUSIONS: This study demonstrated substantial diurnal variation of HRV in participants with SCI in both groups of participants. In clinical and research settings, diurnal variations in HRV must be taken into consideration.

The present study aimed to investigate the effect of the timing of the last meal, \"Suhoor\", on diurnal variation in cognitive performance during Ramadan intermittent fasting (RIF). In a randomized order, 26 adolescent female athletes (aged 15.9 ± 0.9 y) were tested in three sessions at 7:00 a.m., 12:00 p.m., and 5:00 p.m. across four different conditions: the 10 days preceding Ramadan (PR); the final 12 days of Ramadan (RO): two different conditions: Early Suhoor (SEarly), and Late Suhoor (SLate); and, ultimately, the 10 days immediately after Ramadan (AR) with an in-between recovery period of ≥24 h. During each test session, the oral temperature (OT), simple reaction time test (SRT), choice reaction time test (CRT), attention test (ATT), and mental rotation test (MRT) were evaluated. The Pittsburgh Sleep Quality Index (PSQI) and daily diary intake were assessed across the three periods. Compared to PR, the sleep parameters assessed by the PSQI were significantly lower during the RO and AR periods. However, neither total dietary intake nor OT showed any changes due to RIF. Compared to PR, the afternoon performances of SRT, CRT, ATT, and MRT significantly declined under both the SEarly and SLate conditions. Notably, midday performance decreased only during SLate, while morning performance remained unaffected in both conditions. Additionally, compared to SEarly, these performances were better during SLate in the afternoon and at midday. In summary, nutrient intake timing had a significant effect on the diurnal fluctuations in cognitive functions during Ramadan fasting, particularly around noon and in the afternoon. Our results illustrate the benefits of a late last meal (Suhoor) in preserving optimal morning cognitive abilities and preventing any impairment during the fasted state at midday or in the afternoon, which could affect overall athletic performance.

OBJECTIVE: Obstructive sleep apnea is a known risk factor for the progression of chronic kidney disease. To find early signs of the progression in subjects with obstructive sleep apnea., we assessed the diurnal variation of kidney biomarkers.
METHODS: A prospective observational study was conducted at Kangwon National University Hospital, Chuncheon, South Korea. All participants underwent in-laboratory polysomnography and phlebotomy in the evening before the polysomnography and in the morning after the polysomnography. Kidney biomarkers, including serum creatinine, blood urea nitrogen, and serum cystatin C, were measured. Delta kidney biomarkers were calculated by subtracting the evening level of the biomarkers from the morning level.
RESULTS: Twenty-six of 50 participants had severe obstructive sleep apnea. Delta cystatin C was significantly correlated with apnea-hypopnea index, oxygen desaturation index, and total arousal index with coefficients of -0.314, -0.323, and -0.289, respectively. In participants without severe obstructive sleep apnea, the morning cystatin C level (0.84 ± 0.11 mg/L) was significantly higher than the evening cystatin C level (0.81 ± 0.11 mg/L) (P = 0.005). With severe obstructive sleep apnea, the cystatin C levels were not different between the morning (0.85 ± 0.11 mg/L) and the evening (0.85 ± 0.10 mg/L).
CONCLUSIONS: Cystatin C level was increased in the morning in participants without severe obstructive sleep apnea, but not in participants with severe obstructive sleep apnea.

BACKGROUND: Idiopathic membranous nephropathy (IMN) is a leading cause of end-stage renal disease (ESRD). The purpose of this study was to evaluate whether urinary albumin-to-creatinine ratio (UACR) diurnal variation rate calculated by spot urinary protein test predicts 1-year nephrotic outcomes as a biomarker of proteinuria severity in patients with IMN.
METHODS: Patients\' baseline demographics, blood and urinary biomarkers, and clinical and pathological characteristics were collected retrospectively. Urine samples were collected at 7:00 (before breakfast) and 19:00 (after dinner) to calculate the UACR diurnal variation rate. A prediction model for no remission (NR) was developed statistically based on differences between prognosis groups. Receiver operating characteristic curve (ROC) analysis was performed to evaluate prediction abilities and determine optimal cut-off points of the model and UACR diurnal variation rate alone.
RESULTS: The formula for calculating the probability of NR was exp(L)/(1 + exp(L)), where the linear predictor L =  - 22.038 + 0.134 × Age (years) + 0.457 × 24-h urinary protein + 0.511 × blood urea nitrogen (BUN) + 0.014 × serum uric acid (SUA) + 2.411 if glomerular sclerosis + 0.816 × fasting blood glucose (FBG)-0.039 × UACR diurnal variation rate (%). Optimal cut-off points for NR prediction by the final model and UACR diurnal variation rate alone were 0.331 and 58.5%, respectively. Sensitivity and specificity were 0.889 and 0.859 for the final model, and 0.926 and 0.676 for UACR diurnal variation rate alone.
CONCLUSIONS: UACR diurnal variation using spot urinary protein is a simpler way to predict nephrotic outcomes and is a highly sensitive screening tool for identifying patients who should undergo further comprehensive risk assessment.

The ocean absorbs a significant amount of carbon dioxide (CO2) from the atmosphere, helping regulate Earth\'s climate. However, our knowledge of ocean CO2 sink levels remains limited. This research focused on assessing daily changes in ocean CO2 sink levels and air-sea CO2 exchange, using a new technique. We used LiDAR technology, which provides continuous measurements during day and night, to estimate global ocean CO2 absorption over 23 years. Our model successfully reproduced sea surface partial pressure of CO2 data. The results suggest the total amount of CO2 absorbed by oceans is higher at night than during the day. This difference arises from a combination of factors like temperatures, winds, photosynthesis, and respiration. Understanding these daily fluctuations can improve predictions of ocean CO2 uptake. It may also help explain why current carbon budget calculations are not fully balanced-an issue scientists have grappled with. Overall, this pioneering study highlights the value of LiDAR\'s unique day-night ocean data coverage. The findings advance knowledge of ocean carbon cycles and their role in climate regulation. They underscore the need to incorporate day-night variability when assessing the ocean\'s carbon sink capacity.

Background The diurnal variation of testosterone in women has received limited attention, despite its growing recognition as a crucial factor in female health and well-being. This study aims to investigate the diurnal fluctuations of total testosterone levels in apparently healthy women with regular menstrual cycles. Methodology A cross-sectional study was conducted at Faiha Specialized Diabetes Endocrine and Metabolism Center in July 2023. This study involved 46 apparently healthy women volunteers aged between 21 and 40 years. To explore diurnal variations in total testosterone, blood samples were collected from each participant at two distinct time points, i.e., 8:30 AM and 1:30 PM. These samples were collected regardless of fasting status with the exclusion of the menstruating phase. Results The mean total testosterone level at 8:30 AM was 23.4 ± 12.4 ng/dL and at 1:30 PM was 21.7 ± 12.9 ng/dL, with a p-value of 0.03. Neither age nor body mass index demonstrated a significant impact on testosterone levels. Conclusions This study showed a significant diurnal variation in serum total testosterone levels among apparently healthy women, with higher levels observed in the morning.

In this study, we assessed the effects of different harvest times (9 a.m., 1 p.m., and 5 p.m.) and hydrodistillation times (60, 90, and 120 min) on the yield, chemical composition, and antioxidant activity of the spearmint (Mentha spicata L.) essential oil (EO) sourced from the Amazon region. EO yield was ≥1.55% and was not significantly influenced (p ≥ 0.05) by the different harvest times and hydrodistillation times. Thirty-one different organic compounds were identified, of which menthol (91.56-95.68%), menthone (0.6-2.72%), and isomenthone (0.55-1.46%) were the major constituents. The highest menthol content in the EO was obtained from samples collected at 9 a.m., with a hydrodistillation time of 60-90 min, compared to other harvest and hydrodistillation times. This suggests that exposure to sun and light, which is greater at harvest times of 1 p.m. and 5 p.m., decreased the menthol content and altered the chemical composition of Mentha EO. Furthermore, the sample harvested at 9 a.m. and hydrodistilled for 60 min showed the highest antioxidant activity (61.67 equivalent mg of Trolox per g of EO), indicating that antioxidant activity is strongly affected by light exposure and the contact duration of the sample with boiling water during hydrodistillation.

The human body possesses a unique set of machinery called the molecular/biological clocks that function on a regular 24-h basis forming a circadian rhythm (CR). This aids in coordinating the human biological system with ever-changing environmental conditions, thereby maintaining a balance in its functioning. The central/core component of this system is known to be in the suprachiasmatic nucleus of the hypothalamus with a few aides in the periphery. The periodontal ligament in humans, being one of the dynamic oral tissues, has been shown to exhibit this self-sustained, innate oscillatory behavior that has gained significant attention from dental surgeons. Though substantial evidence regarding its precise role in maintaining circadian periodicity is still unclear, its indispensable role in dentofacial functioning cannot be denied. This review is an attempt in bringing to light the possible role of circadian periodicity in the functioning of oral tissues in the field of orthodontics with a special focus on its role in bone remodeling, orthodontic tooth movement, orthopedic and functional appliances, pain management, and their clinical implications. This could provide a better understanding of the various physiologic and pathologic processes and help us refine our approach toward orthodontic diagnosis and therapeutics. This review would therefore serve as an overview, opening more avenues for further research on this topic that can greatly help the orthodontic fraternity.