Lack of exposure to natural light in the workspace is associated with physiological,sleep and depressive symptoms

The diurnal light cycle has a crucial influence on all life on earth. Unfortunately, modern society has modified this life-governing cycle by stressing maximum production and by giving insufficient attention to the ecological balance and homeostasis of the human metabolism. The aim of this study is to evaluate the effects of exposure or lack of exposure to natural light in a rest/activity rhythm on cortisol and melatonin levels, as well as on psychological variables in humans under natural conditions. This is a cross-sectional study. The subjects were allocated split into two groups according to their workspace (10 employees in the “with window” group and 10 in the “without window” group). All participants were women and wore anactigraph (Actiwatch 2, Philips Respironics), which measures activity and ambient light exposure, for seven days. Concentrations of melatonin and cortisol were measured from the saliva samples. Participants were instructed to collect saliva during the last day of use of the actigraph at 08:00 am, 4:00 pm and 10:00 pm. The subjects answered the Self-Reporting Questionnaire-20 (SRQ-20) to measure the presence of minor psychiatric disorders; the Montgomery-Asberg (MA) scale was used to measure depression symptoms, and the Pittsburgh Sleep Quality Index questionnaire (PSQI) was used to evaluate the quality of sleep. The Rayleigh analysis indicates that the two groups, “with window” an d “without window”, exhibited similar activities and light acrophases. In relation to light exposure, the mesor was significantly higher (t?=??2.651, p?=?0.023) in t he “with window” group (191.04?±?133.36) than in the “without window” group (73.8?±?42.05). Additionally, the “with window” group presented the highest amplitude of light exposure (298.07?±?222.97). Cortisol levels were significantly different between the groups at 10:00 pm (t?=?3.009, p?=?0.008; “without window” (4.01?±?0.91) “with window” (3.10?±?0.30)). In terms of the melatonin levels, the groups differed at two different times of day: 08:00 am (t?=?2.593, p?=?0.018) and 10:00 pm (t?=??2.939, p?=?0.009). The “with window” group had a lower melatonin level at 08:00 am (3.54?±?0.60) but a higher level at 10:00 pm (24.74?±?4.22) than the “without window” group. Higher cortisol levels were positively correlated with minor psychiatric disorders and depressive symptoms (MA) at 10:00 pm. Lower melatonin levels at 10:00 pm were correlated with depressive symptoms and poor quality of sleep (PSQI). Our study demonstrated that not only may light pollution affect human physiology but also lack of exposure to natural light is related to high levels of cortisol and lower levels of melatonin at night, and these, in turn, are related to depressive symptoms and poor quality of sleep.     

INCREASED SENSITIVITY TO LIGHT-INDUCED MELATONIN SUPPRESSION IN PREMENSTRUAL DYSPHORIC DISORDER

Increased sensitivity to light-induced melatonin suppression characterizes some, but not all, patients with bipolar illness or seasonal affective disorder. The aim of this study was to test the hypothesis that patients with premenstrual dysphoric disorder (PMDD), categorized as a depressive disorder in Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), have altered sensitivity to 200 lux light during mid-follicular (MF) and late-luteal (LL) menstrual cycle phases compared with normal control (NC) women. As an extension of a pilot study in which the authors administered 500 lux to 8 PMDD and 5 NC subjects, in the present study the authors administered 200 lux to 10 PMDD and 13 NC subjects during MF and LL menstrual cycle phases. Subjects were admitted to the General Clinical Research Center (GCRC) in dim light (<50 lux) to dark (during sleep) conditions at 16:00?h where nurses inserted an intravenous catheter at 17:00?h and collected plasma samples for melatonin at 30-min intervals from 18:00 to 10:00?h, including between 00:00 and 01:00?h for baseline values, between 01:30 and 03:00?h during the 200 lux light exposure administered from 01:00 to 03:00?h, and at 03:30 and 04:00?h after the light exposure. Median % melatonin suppression was significantly greater in PMDD (30.8%) versus NC (?0.2%) women (p?=?.040), and was significantly greater in PMDD in the MF (30.8%) than in the LL (?0.15%) phase (p?=?.047). Additionally, in the LL (but not the MF) phase, % suppression after 200 lux light was significantly positively correlated with serum estradiol level (p ?=? .007) in PMDD patients, but not in NC subjects (p?>?.05). (Author correspondence: bparry@ucsd.edu)     

LIGHT INTENSITY EXPOSURE,SLEEP DURATION,PHYSICAL ACTIVITY,AND BIOMARKERS OF MELATONIN AMONG ROTATING SHIFT NURSES

Long-term, night shiftwork has been identified as a potential carcinogenic risk factor. It is hypothesized that increased light at night exposure during shiftwork reduces melatonin production, which is associated with increased cancer risk. Sleep duration has been hypothesized to influence both melatonin levels and cancer risk, and it has been suggested that sleep duration could be used as a proxy for melatonin production. Finally, physical activity has been shown to reduce cancer risk, and laboratory studies indicate it may influence melatonin levels. A cross-sectional study of light exposure, sleep duration, physical activity, and melatonin levels was conducted among 61 female rotating shift nurses (work schedule: two 12?h days, two 12?h nights, five days off). Light intensity was measured using a light-intensity data logger, and sleep duration and physical activity were self-reported in a study diary and questionnaire. Melatonin concentrations were measured from urine and saliva samples. The characteristics of nurses working day and night shifts were similar. Light intensity was significantly higher during sleep for those working at night (p<?0.0001), while urinary melatonin levels following sleep were significantly higher among those working days (p?=?0.0003). Mean sleep duration for nurses working during the day (8.27?h) was significantly longer than for those working at night (4.78?h, p<?0.0001). An inverse association (p?=?0.002) between light exposure and urinary melatonin levels was observed; however, this was not significant when stratified by shift group. There was no significant correlation between sleep duration and melatonin, and no consistent relationship between physical activity and melatonin. Analysis of salivary melatonin levels indicated that the circadian rhythms of night workers were not altered, meaning peak melatonin production occurred at night. This study indicates that two nights of rotating shift work may not change the timing of melatonin production to the day among those working at night. Additionally, in this study, sleep duration was not correlated with urinary melatonin levels, suggesting it may not be a good proxy for melatonin production. (Author correspondence: anne.grundy@queensu.ca)     

Nutritional status and eating habits of bus drivers during the day and night

The aim of this study was to compare anthropometry and food intake patterns in bus drivers working during the day and night. One hundred and fifty males (81 night workers and 69 day workers) participated in the study. Dietary intake was assessed using a validated semi-quantitative food frequency questionnaire. Measurements of height, weight, waist circumference (WC), systolic and diastolic blood pressure, blood glucose, and lipid profile were obtained. A significant difference between groups was observed for mean WC (98.5?±?10.7?cm in day workers versus 103.2?±?9.7?cm in night workers; p?=?0.005). Night workers had higher prevalence of being overweight and obese (BMI?≥?25?kg/m²) than day workers (78.2% day workers versus 90.2% night workers; p?=?0.004) and increased WC (>94?cm) (72.4% day workers versus 86.4% night workers; p?=?0.03). Significant differences were found for meat consumption (2.3 servings ±0.9 for night workers versus 2.0 servings ±0.7 day workers, p?=?0.04) and fruit intake (0.9 servings ±0.4 for night workers versus 0.7 servings for day workers ±0.5; p?=?0.006). Night workers had a lower intake of vegetables than recommended compared to day workers (100 versus 92.7%, respectively, p?=?0.01) and higher intake of oil (40.7 versus 24.6%, p?=?0.03). Multivariate logistic regression analysis indicated that night work was associated with being overweight (OR?=?2.94, 95% IC: 1.14–7.66, p?=?0.03) and abnormal values of WC (OR?=?2.82, 95% IC: 1.20–6.69, p?=?0.009) after adjusting for potential confounders. It is concluded that night workers had a higher prevalence and risk of being overweight/obese and increased WC compared with day workers. Night workers also presented a higher proportion of inappropriate intakes of food groups when compared to day workers, even though both groups were eating poor diets. These results demonstrate the need of lifestyle-intervention programs in these workers.     

Effects of Filtering Visual Short Wavelengths During Nocturnal Shiftwork on Sleep and Performance

Circadian phase resetting is sensitive to visual short wavelengths (450–480?nm). Selectively filtering this range of wavelengths may reduce circadian misalignment and sleep impairment during irregular light-dark schedules associated with shiftwork. We examined the effects of filtering short wavelengths (<480?nm) during night shifts on sleep and performance in nine nurses (five females and four males; mean age?±?SD: 31.3?±?4.6 yrs). Participants were randomized to receive filtered light (intervention) or standard indoor light (baseline) on night shifts. Nighttime sleep after two night shifts and daytime sleep in between two night shifts was assessed by polysomnography (PSG). In addition, salivary melatonin levels and alertness were assessed every 2?h on the first night shift of each study period and on the middle night of a run of three night shifts in each study period. Sleep and performance under baseline and intervention conditions were compared with daytime performance on the seventh day shift, and nighttime sleep following the seventh daytime shift (comparator). On the baseline night PSG, total sleep time (TST) (p?<?0.01) and sleep efficiency (p?=?0.01) were significantly decreased and intervening wake times (wake after sleep onset [WASO]) (p?=?0.04) were significantly increased in relation to the comparator night sleep. In contrast, under intervention, TST was increased by a mean of 40?min compared with baseline, WASO was reduced and sleep efficiency was increased to levels similar to the comparator night. Daytime sleep was significantly impaired under both baseline and intervention conditions. Salivary melatonin levels were significantly higher on the first (p?<?0.05) and middle (p?<?0.01) night shifts under intervention compared with baseline. Subjective sleepiness increased throughout the night under both conditions (p?<?0.01). However, reaction time and throughput on vigilance tests were similar to daytime performance under intervention but impaired under baseline on the first night shift. By the middle night shift, the difference in performance was no longer significant between day shift and either of the two night shift conditions, suggesting some adaptation to the night shift had occurred under baseline conditions. These results suggest that both daytime and nighttime sleep are adversely affected in rotating-shift workers and that filtering short wavelengths may be an approach to reduce sleep disruption and improve performance in rotating-shift workers. (Author correspondence: casper@lunenfeld.ca)     

Increases in serum concentration of human heart-type fatty acid-binding protein following elective coronary intervention

Background: Heart-type fatty acid-binding protein (H-FABP) is considered a marker of myocardial necrosis but whether or not it is modified by myocardial ischemia is not clear. We sought to investigate if H-FABP serum levels increase following non-urgent coronary angioplasty.

Methods: We studied 31 patients undergoing coronary angioplasty. Peripheral venous samples were drawn immediately before angioplasty, 1?h after the first balloon inflation and 24?h after the procedure and assayed for H-FABP.

Results: Serum levels of H-FABP increased significantly at 1?h vs baseline from 2554?±?1268 to 3322?±?245?pg?ml^?1 (p?=?0.024). However, no differences were observed between 1?h and 24?h after angioplasty (3268?±?1861 vs 3322?±?2459?pg ml^?1, p?=?0.87). Moreover, no significant difference was observed when we compared 24?h after angioplasty with the baseline (3268?±?1861vs 2554?±?1268?pg ml^?1, p?=?0.112).

Conclusions: We conclude that H-FABP significantly increases after elective coronary angioplasty at 1?h compared with baseline values; whether or not this has any prognostic significance for future events, as it occurs with troponins, needs to be studied further.     

Sleep pattern is associated with adipokine levels and nutritional markers in resident physicians

Shift work and long hours of work are common in medical training and have been associated with a higher propensity for developing nutritional problems and obesity. Changes in leptin and ghrelin concentrations – two hormones that contribute importantly to the central regulation of food intake – are poorly described in this population. The aim of this study was to identify possible negative associations between sleep patterns, nutritional status and serum levels of adipokines. The study included 72 resident physicians (52 women and 20 men) who underwent the following assessments: nutritional assessment (3-day dietary recall evaluated by the Adapted Healthy Eating Index), anthropometric variables, fasting metabolism, physical activity level, sleep quality and sleepiness. Resident physicians with poor sleep quality reported greater weight gain after the beginning of residency (5.1 and 3.0?kg, respectively; p?=?0.01) and higher frequency of abnormal waist circumference (44.2 and 17.6%, respectively; p?=?0.04) than those with better sleep quality. Mean ghrelin concentration was greater in volunteers with poor sleep quality (64.6?±?67.8 and 26.2?±?25.0?pg/mL, respectively; p?=?0.04). Women identified as having excessive daytime sleepiness had lower levels of leptin (9.57?±?10.4?ng/mL versus 16.49?±?11.4?ng/mL, respectively; p?=?0.03) than those without excessive sleepiness. Furthermore, correlations were found between hours of additional work per week and: intake of cereals, bread and pasta (r?=?0.22, p?=?0.01); intake of servings of fruits (r?=??0.20; p?=?0.02) and beans (r?=??0.21; p?=?0.01); and global score for Adapted Healthy Eating Index (r?=??0.23; p?=?0.008; Table 3). The sleep quality total score correlated with servings of beans (r?=??0.22; p?=?0.01) and servings of oils (r?=?0.23; p?=?0.008). Significant correlations were found between mean of time of sleep and servings of cereals, bread and pasta (r?=?0.20; p?=?0.02), servings of meat (r?=??0.29; p?=?0.02) and cholesterol levels (r?=?0.27; p?=?0.03). These observations indicate that sleep patterns and long working hours of resident physicians are negatively associated with biological markers related to central food control, the lipid profile, cholesterol levels and eating healthy foods. These factors may predispose these shift workers to become overweight and develop metabolic disorders.     

Diagnostic value of exercise-induced changes in circulating high sensitive troponin T in stable chest pain patients

Abstract

Objective: We investigated the diagnostic value of exercise-induced increase in cardiac Troponin T (cTnT) in stable chest pain subjects.

Methods: CTnT was measured before and 20?h after an exercise test in 157 subjects suspected of coronary artery disease (CAD).

Results: CAD subjects (n?=?41) had higher baseline cTnT levels compared to non-CAD subjects (n?=?116), 6.39?ng/l and 3.00?ng/l, respectively, p?<?0.0001, and were more likely to increase in cTnT (70.7% versus 27.6%, p?<?0.0001). Net Reclassification Index for the combined variable was 19%, p?=?0.02.

Conclusions: Exercise-induced increase in cTnT was found to be associated with CAD and cTnT measurements improved the diagnostic evaluation.     

Influence of acoustic stimulation on the circadian and ultradian rhythm of premature infants

The aim of the present study was to evaluate the development of the circadian rhythm of the salivary cortisol in premature infants and its correlation with the onset of the sleep–activity behavior pattern during the first 3 weeks of life under controlled light:dark conditions. Furthermore, we investigated the influence of acoustic stimulation by audiotaped lullabies or the maternal voice on the cortisol values and long-term sleep–activity patterns. The study was a block-randomized, prospective clinical trial with a study population of 62 preterm neonates (30?<?37 gestational age). We compared two study groups who listened either to music or to the maternal voice (music: N?=?20; maternal voice: N?=?20) with a matched control group (N?=?22). The acoustic stimulation took place every evening between 20:00 and 21:00?h for 30?min over a period of 2 weeks. The cortisol values and activity–rest behavior of the neonates were determined during the first 3 weeks of life on the 1st, 7th and 14th day. Actigraphic monitoring was used to record the activity pattern continuously over 24?h and a validated algorithm for neonates was used to estimate sleep and wakefulness. The saliva samples were obtained 10?min before and 10?min after the acoustic interventions for the study groups. Additionally, saliva samples were obtained from the control group seven times over a 24-h period (20:00, 21:00, 01:00, 05:00, 08:00, 13:00 and 17:00?h). The cortisol data were analyzed by fast Fourier transformation to assess periodic characteristics and frequencies. Hierarchical linear modeling was further performed for the statistical analysis. Results: The cortisol rhythm analysis indicated a circadian rhythm pattern for only one premature infant, all others of the neonates showed no circadian or ultradian rhythm in cortisol. Cortisol level of the premature neonates was significantly higher during the first day of the study period at night-time (median: 17.1?nmol/L, IQR?=?9.7–24.4?nmol/L) than on days 7 (median: 9.6?nmol/L, IQR?=?4.7–14.6?nmol/L; Tukey-HSD, z?=?4.12, p?<?0.001) and 14 (IQR?=?5.8–13.7?nmol/L; Tukey-HSD, z?=?2.89, p?<?0.05). No significant effect of acoustic stimulation was observed on the cortisol concentration and sleep–wake behavior. The activity–sleep rhythm of preterm neonates was dominated by ultradian rhythm patterns with a prominent period length of 4?h (30.5%). Activity frequencies of neonates were also significantly higher overnight on the first study day (mean: 329?±?185.1?U) than of night seven (mean: 260.2?±?132.4?U; Tukey-HSD, z?=?2.50, p?<?0.05). Quiet-activity patterns increased, whereas high-activity patterns decreased during the observation period. Average sleep time increased significantly during the study time from day 1 to day 7 (Tukey-HSD, z?=?2.51, p?<?0.05). In conclusion, premature infants showed higher cortisol levels – without a circadian rhythmicity – and higher activity frequencies in the first days after birth which may reflect an adaptation process of neonates after birth. Cortisol concentrations and the activity patterns were not influenced by music interventions.     

Relationship of troponin to incident atrial fibrillation occurrence,recurrence after radiofrequency ablation and prognosis: a systematic review,meta-analysis and meta-regression

Objective: To explore the association between the levels of troponin (Tn) and incident atrial fibrillation (AF) occurrence, AF recurrence after radiofrequency ablation (RFA), and the risk trend of AF related prognosis (stroke, major bleeding and mortality).

Methods: Twenty-seven studies were included after a systematic search in PubMed from 2005 to 2017, including 13 associated with incident AF occurrence, 8 associated with AF recurrence after RFA and 6 studies evaluating the risk trend of AF-related prognosis with increased Tn levels.

Results: Compared with ‘no incident AF occurrence’ patients, the incident AF occurrence group had similar baseline troponin I (TnI) levels (standardized mean differences [SMD]?=?0.42, 95% CI: ?0.02–0.86, p?=?0.06; I²?=?87.0%, N?=?6), but higher troponin T (TnT) levels (SMD?=?3.77, 2.13–5.42, p?<0.001; I²=99.7%, N?=?8). AF recurrence patients had similar peri-ablation TnI levels, but higher peri-ablation TnT levels compared to the ‘no AF recurrence’ group with pooled SMD. (TnI: SMD: ?0.61, ?1.22to 0, p?=?0.049; I²?=?87.1%; TnT: 0.38, 0.14–0.62, p?=?0.002; I²?=?64.7%). On meta-regression, there was an increased risk trend for stroke/systemic embolism (SE) (r²?=?0.93, p?=?0.04) or major bleeding (r²?=?0.99, p?r²?=?0.09, p?=?0.25) or TnT (r²?=?0.20, p?=?0.31), and stroke/SE (r²?=?0.02, p?=?0.74) or major bleeding (r²?=?0.002, p?=?0.92) was non-significantly related to increasing TnI levels.

Conclusions: In our systematic review, meta-analysis and meta-regression, TnT was associated with both incident AF occurrence and AF recurrence after RFA, as well as stroke/SE and major bleeding. In contrast, TnI was not associated with incident AF occurrence, AF recurrence after RFA or prognosis (stroke/SE, major bleeding).     

Phototherapy and Orange-Tinted Goggles for Night-Shift Adaptation of Police Officers on Patrol

The aim of the present combined field and laboratory study was to assess circadian entrainment in two groups of police officers working seven consecutive 8/8.5-h night shifts as part of a rotating schedule. Eight full-time police officers on patrol (mean age?±?SD: 29.8?±?6.5 yrs) were provided an intervention consisting of intermittent exposure to wide-spectrum bright light at night, orange-tinted goggles at sunrise, and maintenance of a regular sleep/darkness episode in the day. Orange-tinted goggles have been shown to block the melatonin-suppressing effect of light significantly more than neutral gray density goggles. Nine control group police officers (mean age?±?SD: 30.3?±?4.1 yrs) working the same schedule were enrolled. Police officers were studied before, after (in the laboratory), and during (ambulatory) a series of seven consecutive nights. Urine samples were collected at wake time and bedtime throughout the week of night work and during laboratory visits (1?×?/3?h) preceding and following the work week to measure urinary 6-sulfatoxymelatonin (UaMT6s) excretion rate. Subjective alertness was assessed at the start, middle, and end of night shifts. A 10-min psychomotor vigilance task was performed at the start and end of each shift. Both laboratory visits consisted of two 8-h sleep episodes based on the prior schedule. Saliva samples were collected 2?×?/h during waking episodes to assay their melatonin content. Subjective alertness (3?×?/h) and performance (1?×?/2?h) were assessed during wake periods in the laboratory. A mixed linear model was used to analyze the progression of UaMt6s excreted during daytime sleep episodes at home, as well as psychomotor performance and subjective alertness during night shifts. Two-way analysis of variance (ANOVA) (factors: laboratory visit and group) were used to compare peak salivary melatonin and UaMT6s excretion rate in the laboratory. In both groups of police officers, the excretion rate of UaMT6s at home was higher during daytime sleep episodes at the end compared to the start of the work week (p?<?.001). This rate increased significantly more in the intervention than control group (p?=?.032). A significant phase delay of salivary melatonin was observed in both groups at the end of study (p?=?.009), although no significant between-group difference was reached. Reaction speed dropped, and subjective alertness decreased throughout the night shift in both groups (p?<?.001). Reaction speed decreased throughout the work week in the control group (p?≤?.021), whereas no difference was observed in the intervention group. Median reaction time was increased as of the 5th and 6th nights compared to the 2nd night in controls (p?≤?.003), whereas it remained stable in the intervention group. These observations indicate better physiological adaptation in the intervention group compared to the controls. (Author correspondence: diane.boivin@douglas.mcgill.ca)     

Comparison of the effects of melatonin and pentoxifylline on carbon tetrachloride-induced liver toxicity in mice

The purpose of the study was to determine whether along and in combination melatonin (MLT) and pentoxlfylline (PTX) exerted beneficial effects on histopathological changes and changes in oxidant and antioxidant systems in liver caused by CCl₄-induced liver toxicity in mice. Mice were randomly divided into six groups: control, olive oil, toxicity, MLT, PTX, PTX+MLT. MLT 10 mg/kg/day, PTX 50 mg/kg/day, and the same individual doses in MLT+PTX combination were given intraperitoneally to mice for 7 day. CCl₄ 0.8 mg/kg/day was administered on the 4th, 5th, and 6th days of therapy in all groups except the control and olive oil groups. In the toxicity group, increased concentrations of malondialdehyde (MDA) and lipid hydroperoxides (LOOH) and decreased glutathione peroxidase (GSH-Px) and catalase (CAT) activities were found compared to the control and olive oil groups (p < 0.05). Compared to the toxicity group, both the PTX group and the PTX+MLT group had decreased MDA and LOOH levels, whereas MLT reduced only LOOH levels (p < 0.01). MLT, PTX and MLT+PTX increased the GSH-Px and CAT activities compared to the toxicity group (p < 0.05). MLT increased CAT activity compared to PTX and MLT+PTX (p < 0.05). Superoxide dismutase enzyme activity did not change in any group (p < 0.05). Histopatholically, ballooning, degeneration, apoptosis, and bridging necrosis were seen in the toxicity group. MLT, PTX and MLT+PTX decreased the apoptosis and bridging necrosis (p < 0.01), and PTX and MLT+PTX decreased balloon degeneration compared to the toxicity group (p < 0.01). These results indicate that administration of PTX and MLT alone and in combination before onset of liver toxicity might prevent the oxidative damage by reducing oxidative stress and increasing antioxidant enzyme levels.     

Association between light exposure at night and nighttime blood pressure in the elderly independent of nocturnal urinary melatonin excretion

Circadian misalignment between internal and environmental rhythms dysregulates blood pressure (BP) variability because of disruption of the biological clock, resulting in increased nighttime BP. Although exposure to light-at-night is associated with the circadian misalignment, it remains unclear whether exposure to light-at-night in home settings is associated with nighttime BP. In this cross-sectional analysis of 528 elderly individuals (mean age: 72.8 years), we measured bedroom light intensity at 1-min intervals on two consecutive nights along with ambulatory BP, overnight urinary melatonin excretion and actigraphy. With regard to adjusted mean comparisons using analysis of covariance, the light-at-night group (average: ≥5?lux; n?=?109) showed significantly higher nighttime systolic BP (SBP; adjusted mean: 120.8 vs. 116.5?mmHg, p?=?0.01) and diastolic BP (70.1 vs. 67.1?mmHg, p?<?0.01) compared with the Darker group (average: <5?lux; n?=?419) independently of potential confounding factors including overnight urinary melatonin excretion and actigraphic sleep quality. We observed consistent associations between light-at-night and nighttime BP in different cutoff values for light-at-night intensity (i.e. 3 and 10?lux). In conclusion, exposure to light-at-night in home settings is significantly associated with increased nighttime BP in elderly individuals independently of overnight urinary melatonin excretion. A 4.3?mmHg increase in nighttime SBP is associated with a 6.1% increase in total mortality, which corresponds to approximately 10?000 annual excess deaths in Japanese elderly population.     

The impact of training schedules on the sleep and fatigue of elite athletes

In any sport, successful performance requires a planned approach to training and recovery. While sleep is recognized as an essential component of this approach, the amount and quality of sleep routinely obtained by elite athletes has not been systematically evaluated. Data were collected from 70 nationally ranked athletes from seven different sports. Athletes wore wrist activity monitors and completed self-report sleep/training diaries for 2 weeks during normal training. The athletes also recorded their fatigue level prior to each training session using a 7-point scale. On average, the athletes spent 08:18?±?01:12?h in bed, fell asleep at 23:06?±?01:12?h, woke at 6:48?±?01:30?h and obtained 06:30?±?01:24?h of sleep per night. There was a marked difference in the athletes’ sleep/wake behaviour on training days and rest days. Linear mixed model analyses revealed that on nights prior to training days, time spent in bed was significantly shorter (p?=?0.001), sleep onset and offset times were significantly earlier (p?<?0.001) and the amount of sleep obtained was significantly less (p?=?0.001), than on nights prior to rest days. Moreover, there was a significant effect of sleep duration on pre-training fatigue levels (p?≤?0.01). Specifically, shorter sleep durations were associated with higher levels of pre-training fatigue. Taken together, these findings suggest that the amount of sleep an elite athlete obtains is dictated by their training schedule. In particular, early morning starts reduce sleep duration and increase pre-training fatigue levels. When designing schedules, coaches should be aware of the implications of the timing of training sessions for sleep and fatigue. In cases where early morning starts are unavoidable, countermeasures for minimizing sleep loss – such as strategic napping during the day and correct sleep hygiene practices at night – should be considered.     

Circadian Phase,Sleepiness, and Light Exposure Assessment in Night Workers With and Without Shift Work Disorder

Most night workers are unable to adjust their circadian rhythms to the atypical hours of sleep and wake. Between 10% and 30% of shiftworkers report symptoms of excessive sleepiness and/or insomnia consistent with a diagnosis of shift work disorder (SWD). Difficulties in attaining appropriate shifts in circadian phase, in response to night work, may explain why some individuals develop SWD. In the present study, it was hypothesized that disturbances of sleep and wakefulness in shiftworkers are related to the degree of mismatch between their endogenous circadian rhythms and the night-work schedule of sleep during the day and wake activities at night. Five asymptomatic night workers (ANWs) (3 females; [mean?±?SD] age: 39.2?±?12.5 yrs; mean yrs on shift?=?9.3) and five night workers meeting diagnostic criteria (International Classification of Sleep Disorders [ICSD]-2) for SWD (3 females; age: 35.6?±?8.6 yrs; mean years on shift?=?8.4) participated. All participants were admitted to the sleep center at 16:00?h, where they stayed in a dim light (<10 lux) private room for the study period of 25 consecutive hours. Saliva samples for melatonin assessment were collected at 30-min intervals. Circadian phase was determined from circadian rhythms of salivary melatonin onset (dim light melatonin onset, DLMO) calculated for each individual melatonin profile. Objective sleepiness was assessed using the multiple sleep latency test (MSLT; 13 trials, 2-h intervals starting at 17:00?h). A Mann-Whitney U test was used for evaluation of differences between groups. The DLMO in ANW group was 04:42?±?3.25?h, whereas in the SWD group it was 20:42?±?2.21?h (z = 2.4; p?<?.05). Sleep did not differ between groups, except the SWD group showed an earlier bedtime on off days from work relative to that in ANW group. The MSLT corresponding to night work time (01:00–09:00?h) was significantly shorter (3.6?±?.90?min: [M?±?SEM]) in the SWD group compared with that in ANW group (6.8?±?.93?min). DLMO was significantly correlated with insomnia severity (r = ?.68; p < .03), indicating that the workers with more severe insomnia symptoms had an earlier timing of DLMO. Finally, SWD subjects were exposed to more morning light (between 05:00 and 11:00?h) as than ANW ones (798 vs. 180 lux [M?±?SD], respectively z?=??1.7; p?<?.05). These data provide evidence of an internal physiological delay of the circadian pacemaker in asymptomatic night-shift workers. In contrast, individuals with SWD maintain a circadian phase position similar to day workers, leading to a mismatch/conflict between their endogenous rhythms and their sleep-wake schedule. (Author correspondence: vgumeny1@hfhs.org)     

Snoring and aortic dimension in Marfan syndrome

Recent reports suggest that self-reported snoring, which is a feature of obstructive sleep apnea, is associated with aortic enlargement in Marfan syndrome (MFS). Objective assessment of snoring although lacking, could provide a rational for OSA screening in MFS patients. Our goal in this study was to examine the association between objective measurements of snoring with OSA and aortic size in persons with MFS. Consecutive persons with MFS who reported snoring were recruited at Johns Hopkins, completed the Epworth Sleepiness Scale (ESS) and underwent overnight polysomnography during which inspiratory sound was captured. We measured breath-by-breath peak decibel levels and snoring was defined as flow limitation with sound?≥?40 dB(A). OSA was defined as an apnea–hypopnea-index (AHI)?≥?15 or AHI: 5–15 and ESS?>?10. Participants’ aortic data were collated to ascertain aortic root diameter. Regression models were used to determine the relationship of snoring breath% with OSA and aortic root diameter. In our cohort (M|F:13|16, Age: 37.0?±?15.5 years, Aortic diameter; 38.9?±?4.8 mm), a 1-unit increase in snoring breath percentage increased the odds of having OSA by 5% in both the unadjusted (OR?=?1.05, p?=?0.040) model, and a model adjusted for age and sex (OR?=?1.05, p?=?0.048). Similarly, a 10-unit increase in snoring breath percentage was associated with a 1 mm increase in contemporaneous aortic-root-diameter in both unadjusted (β?=?0.09, p?=?0.007), and adjusted (β?=?0.08, p?=?0.023) models. Objective snoring assessment could provide a means for identifying persons with MFS who need sleep studies, who may also be at risk for more severe aortic disease.

     

EFFECTS OF LIGHT AND MELATONIN TREATMENT ON BODY TEMPERATURE AND MELATONIN SECRETION DAILY RHYTHMS IN A DIURNAL RODENT,THE FAT SAND RAT

Many mammals display predictable daily rhythmicity in both neuroendocrine function and behavior. The basic rest-activity cycles are usually consistent for a given species and vary from night-active (nocturnal), those mostly active at dawn and dusk (i.e., crepuscular), and to day-active (diurnal) species. A number of daily rhythms are oppositely phased with respect to the light/dark (LD) cycle in diurnal compared with nocturnal mammals, whereas others are equally phased with respect to the LD cycle, regardless of diurnality/nocturnality. Pineal produced melatonin (MLT) perfectly matches this phase-locked feature in that its production and secretion always occurs during the night in both diurnal and nocturnal mammals. As most rodents studied to date in the field of chronobiology are nocturnal, the aim in this study was to evaluate the effect of light manipulations and different photoperiods on a diurnal rodent, the fat sand rat, Psammomys obesus. The authors studied its daily rhythms of body temperature (T_b) and 6-sulphatoxymelatonin (6-SMT) under various photoperiodic regimes and light manipulations (acute and chronic exposures) while maintaining a constant ambient temperature of 30°C?±?1°C. The following protocols were used: (A) Control (CON) conditions 12L:12D; (A1) exposure to one light interference (LI) of CON-acclimated individuals for 30?min, 5?h after lights-off; (A2) short photoperiod (SP) acclimation (8L:16D) for 3 wks; (A3) 3 wks of SP acclimation with chronic LI of 15?min, three times a night at 4-h intervals; (A4) chronic exposure to constant dim blue light (470nm, 30 lux) for 24?h for 3 wks (LL). (B) The response to exogenous MLT administration, provided in drinking water, was measured under the following protocols: (B1) After chronic exposure to SP with LI, MLT was provided once, starting 1?h before the end of photophase; (B2) after a continuous exposure to dim blue light, MLT was provided at 15:00?h for 2?h for 2 wks; (B3) to CON animals, MLT was given intraperitoneally (i.p.) at 14:00?h. The results demonstrate that under CON acclimation, Psammomys obesus has robust T_b and 6-SMT daily rhythms in which the acrophase (peak time) of T_b is during the photophase, whereas that of 6-SMT is during scotophase. LI resulted in an elevation of T_b and a reduction of 6-SMT levels. A significant difference in the response was noted between acute and chronic exposure to LI, particularly in 6-SMT levels, which were lower than CON after LI and higher after chronic LI, implying an acclimation process. Constant exposure to blue light abolished T_b and 6-SMT rhythms in all the animals. MLT administration resumed the T_b daily rhythm in these animals, and had a recovery effect on the chronic LI-exposed animals, resulting in a T_b decrease. Altogether, the authors show in this study the different modifications of T_b rhythms and MLT levels in response to environmental light manipulations. These series of experiments may serve as a basis for establishing P. obesus as an animal model for further studies in chronobiology. (Author correspondence: hagitsc@research.haifa.ac.il)     

Changes in resting motor threshold of the tongue with normal aging and stroke

Aim of study: To examine the resting motor threshold of the tongue in healthy adults and stroke survivors.

Methods: Thirty-five healthy adults were classified into three groups: Group 1 (19–38?years; n?=?11), Group 2 (50–64?years; n?=?12) and Group 3 (66–78?years; n?=?12). Six chronic stroke survivors (mean age =59?years, SD?=?9.1?years) were recruited (Group 4). The resting motor thresholds (RMTs) of the tongue were measured and compared (i) among the four groups and (ii) between stroke survivors and age-matched healthy adults.

Results: Group 3 showed significantly higher RMTs than Group 1 (p?=?.001) and 2 (p =?0.007). Group 4 showed significantly higher RMTs than Group 1 (p =?.003) and 2 (p?=?.001). The RMTs of Group 3 and 4 were not significantly different (p =?.385). The RMT was positively correlated with age (r?=?0.534; p =?.001). Group 4 showed significantly higher RMTs than the age-matched controls (U?= 2.5, p?=?.009, r?=?0.77).

Conclusions: The resting motor threshold of the tongue is significantly increased in adults aged above 65 and in stroke survivors when compared with healthy adults. The findings suggested that the cortical excitability of the tongue deteriorates in the elderly and the stroke population.     

The GALA study: relationship between galectin-3 serum levels and short- and long-term outcomes of patients with acute heart failure

Objective: We tested the hypothesis that early measurement of galectin-3 at the emergency department (ED) during an episode of acute heart failure (AHF) allows predicting short- and long-term outcomes.

Methods: We performed an exploratory study including 115 patients consecutively diagnosed with AHF in a single ED. Clinical and analytical variables were recorded. The primary endpoint was 30-day all-cause mortality, and secondary endpoints were 30-day composite outcome (death, rehospitalization or ED reconsultation, whichever first) and 1-year mortality.

Results: Seven patients (6.1%) died within 30?days and 43 (37.4%) within 1?year. The 30-day composite endpoint was observed in 21.1% of patients. Galectin-3 was correlated with NT-proBNP and the glomerular filtration rate but not with age and s-cTnI. Measured at time of ED arrival, galectin-3 showed good discriminatory capacity for 30-day mortality (AUC ROC: 0.732; 95% CI 0.512–0.953; p?=?0.041) but not for 1-year mortality (0.521; 0.408–0.633; p?=?0.722). Patients with galectin-3 concentrations?>42?μg/L had an OR?=?7.67(95%CI?=?1.57-37.53; p?=?0.012) for 30-day mortality. Conversely, NT-proBNP only showed predictive capacity for 1-year mortality (0.642; 0.537–0.748; p?=?0.014). Patients with NT-proBNP concentrations?>5400?ng/L had an OR?=?4.34 (95%CI?=?1.93-9.77; p?<?0.001) for 1-year mortality. These increased short- (galectin-3) and long-term (NT-proBNP) risks remained significant after adjustment for age or renal function. s-cTnI failed in both short- and long term death prediction. No biomarker predicted the short-term composite endpoint.

Conclusion: These results suggest that galectin-3 could help to monitor the risk of short-term mortality in unselected patients with AHF attended in the ED.     

Bedtime misalignment and progression of breast cancer

Disruption of circadian rhythms, which frequently occurs during night shift work, may be associated with cancer progression. The effect of chronotype (preference for behaviors such as sleep, work, or exercise to occur at particular times of day, with an associated difference in circadian physiology) and alignment of bedtime (preferred vs. habitual), however, have not yet been studied in the context of cancer progression in women with breast cancer. Chronotype and alignment of actual bedtime with preferred chronotype were examined using the Morningness–Eveningness Scale (MEQ) and sleep-wake log among 85 women with metastatic breast cancer. Their association with disease-free interval (DFI) was retrospectively examined using the Cox proportional hazards model. Median DFI was 81.9 months for women with aligned bedtimes (“going to bed at preferred bedtime”) (n?=?72), and 46.9 months for women with misaligned bedtimes (“going to bed later or earlier than the preferred bedtime”) (n?=?13) (log rank p?=?0.001). In a multivariate Cox proportional hazard model, after controlling for other significant predictors of DFI, including chronotype (morning type/longer DFI; HR?=?0.539, 95% CI?=?0.320–0.906, p?=?0.021), estrogen receptor (ER) status at initial diagnosis (negative/shorter DFI; HR?=?2.169, 95% CI?=?1.124–4.187, p?=?0.028) and level of natural-killer cell count (lower levels/shorter DFI; HR?=?1.641, 95% CI?=?1.000–2.695, p?=?0.050), misaligned bedtimes was associated with shorter DFI, compared to aligned bedtimes (HR?=?3.180, 95% CI?=?1.327–7.616, p?=?0.018). Our data indicate that a misalignment of bedtime on a daily basis, an indication of circadian disruption, is associated with more rapid breast cancer progression as measured by DFI. Considering the limitations of small sample size and study design, a prospective study with a larger sample is necessary to explore their causal relationship and underlying mechanisms.