Associations of chronotype and sleep patterns with metabolic syndrome in the Hispanic community health study/study of Latinos.

Sleep duration, sleep efficiency, and sleep timing have been shown to have potential effects on metabolic functions relevant to circadian rhythms. It is not clear if the impact of sleep patterns on metabolic risk factors is through sociocultural and environmental factors or circadian misalignment. We investigated the associations of sleep patterns, chronotype, and social jet lag with metabolic syndrome among non-shift worker Hispanic/Latino adults. We used cross-sectional data from the Sueño Ancillary Study of The Hispanic Community Health Study/Study of Latinos (HCHS/SOL). Data from a subsample of 2189 participants aged 18-64 years were used in the analysis. Mean nightly sleep duration, mean sleep onset time, mean sleep offset time, mean sleep midpoint time, sleep efficiency, sleep variability (standard deviation (SD) of sleep duration, and SD of sleep midpoint), and time spent above light exposure threshold (1000 lux) in a day were assessed by wrist actigraphy (Acti-watch Spectrum). Chronotype was determined by the reduced Morningness-Eveningness Questionnaire. Medical conditions including dyslipidemia, hypertension, and diabetes mellitus were determined from a fasting blood specimen and physical exam at the baseline visit. To determine whether sleep patterns, light levels, chronotype, and social jetlag are associated with metabolic syndrome, multivariable logistic regression models were fitted, including variables with P < .15 in the univariate analysis. The results of the multivariable analysis demonstrated that in participants older than 40 years, intermediate chronotype (vs early) was significantly associated with a higher risk of metabolic syndrome (Odds ratio (95%CI): 1.33 (1.04,1.7)), while later chronotype (vs. early) in participants younger than 40 years was significantly associated with a lower risk of metabolic syndrome (Odds ratio (95%CI): 0.37 (0.14, 0.96)). Also, higher sleep efficiency was significantly associated with decreased odds of metabolic syndrome (Odds ratio (95%CI): 0.98 (0.96, 0.99)). Nightly sleep duration was not significantly different between two groups of participants with and without metabolic syndrome in multivariable analyses. There was no significant association between social jet lag and metabolic syndrome in multivariable analysis (p = .286). Moreover, there was no significant association between chronotype and social jet lag in multivariable analysis. The association between metabolic syndrome and chronotype is age-dependent. While early chronotype is associated with metabolic syndrome in younger individuals, it tended to be associated with lower odds for metabolic syndrome in older individuals.

Time of day, time of sleep, and time on task effects on sleepiness and cognitive performance of bus drivers.

PURPOSE: Optimal cognitive performance might prevent vehicle accidents. Identifying time-related circadian and homeostatic parameters having an impact on cognitive performance of drivers may be crucial to optimize drivers' performance. METHODS: In this prospective study conducted on bus drivers, two drivers alternated driving during a 24-h round trip and were accompanied by an interviewer. Each driver was tested using Karolinska Sleepiness Scale (KSS) and the reversed digit span Wechsler Working Memory test before the start of his shift and then every 6 h during a "work/driving" day. Psychomotor Vigilance Task (PVT) was assessed before and after the journey. Linear mixed model was used to explore the factors affecting cognitive performance and sleepiness in univariate and multivariate analysis. RESULTS: Among 35 bus drivers, the effect of time of day on working memories was statistically significant (p = 0.001), with the lowest working memory scores at 04:00 am (± 1). The highest score of subjective sleepiness was also at 04:00 am (± 1). The time on task parameter affected sleepiness significantly (p = 0.024) and sleepiness was significantly associated with decreased working memory. Psychomotor Vigilance Task reaction time mean and the number of minor lapses were significantly increased after the journey, which suggested decreased vigilance. In multivariable analysis, a longer interval between the beginning of working hours and testing time (B (95% CI) = 15.25 (0.49 to 30), p = 0.043) was associated with higher (i.e., slower) PVT reaction time mean. CONCLUSIONS: These results suggest that optimizing bus drivers' working schedules may improve drivers' sleepiness and cognitive performance and thus increase road safety.

A Pilot Randomized Controlled Trial of Effect of Genioglossus Muscle Strengthening on Obstructive Sleep Apnea Outcomes.

The genioglossus is a major upper airway dilator muscle. Our goal was to assess the efficacy of upper airway muscle training on Obstructive Sleep Apnea (OSA) as an adjunct treatment. Sixty-eight participants with OSA (AHI > 10/h) were recruited from our clinic. They fall into the following categories: (a) Treated with Automatic Positive Airway Pressure (APAP), (n = 21), (b) Previously failed APAP therapy (Untreated), (n = 25), (c) Treated with Mandibular Advancement Splint (MAS), (n = 22). All subjects were given a custom-made tongue strengthening device. We conducted a prospective, randomized, controlled study examining the effect of upper airway muscle training. In each subgroup, subjects were randomized to muscle training (volitional protrusion against resistance) or sham group (negligible resistance), with a 1:1 ratio over 3 months of treatment. In the baseline and the final visit, subjects completed home sleep apnea testing, Epworth Sleepiness Scale (ESS), Pittsburgh Sleep Quality Index (PSQI), SF-36 (36-Item Short Form Survey), and Psychomotor Vigilance Test (PVT). Intervention (muscle training) did not affect the AHI (Apnea-Hypopnea Index), (p-values > 0.05). Based on PSQI, ESS, SF-36 scores, and PVT parameters, the changes between the intervention and sham groups were not significant, and the changes were not associated with the type of treatment (p-value > 0.05). The effectiveness of upper airway muscle training exercise as an adjunct treatment requires further study.

Evaluation of occupational and non-occupational risk factors associated with carpal tunnel syndrome in dentists.

BACKGROUND: Musculoskeletal disorders are very prevalent among dentists. Of these disorders, carpal tunnel syndrome (CTS) is notable. OBJECTIVE: The aim of this study was to investigate the relationship between the occupational and non-occupational risk factors and CTS among dentists. METHODS: It is a cross-sectional study. We evaluated 106 dentists from dental schools in Tehran. We collected data by a general questionnaire, a hand diagram, and physical examination. A nerve conduction velocity (NCV) test was used to confirm the diagnosis of CTS. The analysis was performed using an independent T-test and logistic regressions on SPSS software. RESULTS: The prevalence of CTS among dentists was 17.9%. Significant risk factors of CTS included: vibration exposure greater than two hours per day (OR: 2.5), a wrist diameter ratio of greater than 0.7 (OR: 10.14), and female sex (OR: 13.38). CONCLUSIONS: Exposure to the hand-arm vibration should be considered as an occupational risk factor for CTS in dentists. Female dentists should take more preventive measures.

Impact of music type on motor coordination task performance among introverted and extroverted students.

Purpose. People are interested in music. In this study, we assessed the impact of music type on objective performance. Materials and methods. We distributed 64 medical science students in Tehran into four groups: Iranian pop music, traditional music, Mozart's classical music and control groups. All participants performed the two-arm coordination test once without music and once with music (except for the control group), with an interval of 1 week. In the music groups, music was playing during the performance of the test. Participants were categorized as either introverted or extroverted and were distributed equally in the groups. Results. There was a significant decrease of test time in the second trial, observed in all music groups, and no significant difference identified in the control group. The traditional music group had less difference of mean time compared to the pop music group. The differences in the traditional and classical groups were not significantly different. In the music groups, both extroverted and introverted students decreased their test time significantly after music intervention, but extroverted students decreased more. Conclusion. Listening to music would enhance the speed of performance. Music with a higher tempo, such as pop music, increased the speed more.

Coefficient of friction, walking speed and cadence on slippery and dry surfaces: shoes with different groove depths.

Objective. The present study aimed to determine the coefficient of friction (COF), walking speed (WS) and cadence while walking on slippery and dry surfaces using shoes with different sole groove depths to predict likelihood of fall. Background. Design of shoe sole groove is crucial to prevent slipping during walking. Methods. 22 healthy young men (mean age 24.5, body mass index 22.5) volunteered for this semi-experimental study. Six different conditions of the test (combination of three shoes and two surfaces) were defined and the condition was repeated three times. In total, 396 trials (22 subjects × 3 groove depths × 2 surfaces × 3 times) were obtained for data analysis. COF was recorded by force platform at 1000 Hz and walking parameters recorded using 3D motion analysis with six infrared cameras at 200 Hz. Results. The highest COF was obtained from the deepest groove depth (5.0 mm) on both dry and slippery surfaces. The COF on slippery surfaces was significantly lower in comparison with dry surfaces. WS and cadence were not significantly different on dry and slippery surfaces. Conclusion. The deeper groove is better to prevent slipping because the COF increases by increasing the shoe sole groove depth. WS did not change on dry and slippery surfaces.

The relationship between emotional intelligence, reaction time, aerobic capacity and performance in female track and field athletes at the Universities of Tehran.

BACKGROUND: In order to be successful in sport, athletes need a high level of physical skills as well as cognitive abilities. OBJECTIVE: The aim of this studywas to investigate the relationship between emotional intelligence, reaction time, aerobic capacity and performance (recorded time) in female track & field athletes at the Universities of Tehran. METHODS: Data was collected from 100 female athletes participating in sprints.The emotional intelligence in athletes was measured by the Bar-On questionnaire, the reaction time was assessed by the psychomotor vigilance task, and maximal aerobic capacity was predicted by step test. Pearson correlation calculations were conducted to investigate the potential relationships between emotional intelligence total score, reaction time, and estimated VO2max, with recorded time of the students. RESULTS: Average age of female athletes was 20.59 years (±1.55) and mean height of them was 163.63 cm (±6.03).The mean emotional intelligence in athletes was 302.05 (±20.18), the mean reaction time was 431.14 ms (±114.88), and mean maximal aerobic capacity was predicted as 62.82 ml/ kg.min (±0.6). The findings revealed that there is no significant correlation between emotional intelligence and recorded time or athletic performance (p > 0.05).There were significant correlations between some components of emotional intelligence (empathy, interpersonal relations, and independence) and athletes' recorded time. Reaction time and aerobic capacity were significantly correlated with athletes' performance (p < 0.05). CONCLUSION: Increased aerobic capacity and decreased response time (reaction time) resulted in better performance (shorter recorded time) in female student athletes.

The prevalence of occupational musculoskeletal disorders in Iran: A meta-analysis study.

BACKGROUND: Prevention of Work-Related Musculoskeletal Disorders (WRMSDs) is crucial as they jeopardize the well-being of the workforce in workplaces and are prevalent in developed and developing countries. OBJECTIVE: This study aimed to determine the prevalence of WRMSDs among Iranian workers. METHODS: A systematic review and meta-analysis of WRMSDs in Iran was performed by searching relevant keywords in authentic databases and search engines such as SID, Google Scholar, Medlib and PubMed. Twenty-seven published articles in the field of WRMSDs from 2001 to 2010 were searched. Meta-analysis and random effects approach were used to analyze data. Heterogeneity investigation of articles was done using I2 index. RESULTS: The total sample size was 6,090 workers with a mean of 225 samples per study. The upper and lower back had the highest prevalence rate of self-reported WRMSDs with 38.1% (95% CI: 29.9-46.4), and 50% (95% CI: 42.5-57.5), respectively. Also, knee had the highest prevalence among lower extremity disorders with 42.1% prevalence rate (95% CI:35.1-49.1). CONCLUSIONS: A high prevalence of WRMSDs in upper and lower limbs was reported in Iran. Trainings with regard to occupational ergonomics and industrial hygiene programs were recommended for minimizing the work-related risks of musculoskeletal disorders.

Safety climate and prediction of ergonomic behavior.

One of the most important ways to prevent accidents is to consider safety climate or culture. Moreover, some studies suggest that behavior contributes to 86%-96% of all injuries. This cross-sectional study took place in an Iranian petrochemical company in 2010. Vinodkumar and Bhasi's safety climate questionnaire and an ergonomic behavior sampling checklist were the data collection tools. Cronbach's α for questionnaire reliability was .928. With reference to the results of a pilot study, a sample of 1755 was determined for behavior sampling. We used principal component analysis (PCA) to derive the coefficient of paths in the path model and the Anderson-Rabin method to calculate factor scores. The results showed that safety climate was an effective predictor of ergonomic behavior (p < .01). They also showed the importance of decreasing the number of workers with negative safety climate. Moreover, it is necessary to promote workers' ergonomic behaviors in the workplace.

Retinal nerve fiber thickness is reduced in sleep apnea syndrome.

OBJECTIVE: To investigate the prevalence of glaucoma, visual field abnormalities, as well as changes in retinal nerve fiber layer in patients with obstructive sleep apnea syndrome (OSAS). METHODS: In this cross-sectional study, 51 patients with OSAS were included. Based on apnea hypopnea index (AHI), there were 26, 6 and 19 cases of severe (AHI⩾30), moderate (15⩽AHI<30), and mild (5⩽AHI<15) OSAS, respectively. The control group was matched for age, sex and body mass index. Prevalence of glaucoma and ocular hypertension as well as the following values were assessed and compared between two groups: best-corrected visual acuity, intraocular pressure, central corneal thickness (CCT), cup:disk ratio, mean deviation (MD), pattern standard deviation, and retinal nerve fiber layer (RNFL) parameters using glaucoma diagnosis measurement (GDx). RESULTS: Seven eyes (6.7%) had intraocular pressure (IOP)>21mmHg; of these, four eyes (3.9%) had glaucoma. No significant difference was detected in CCT between the two groups. IOP was significantly higher in the OSAS group before (p<0.001) and after (p<0.001) correcting for CCT. There was a significant difference between groups in MD and most GDx parameters including DISK (temporal-superior-nasal-inferior-temporal) average (p=0.002), superior average (p=0.05) and nerve fiber indicator (NFI) (p=0.03), where those in the patient group showed lower values. There was a significant positive correlation between AHI and both IOP and NFI. CONCLUSIONS: OSAS patients had a higher prevalence of glaucoma and ocular hypertension. OSAS patients also had higher IOP, worse visual field indices, and lower RNFL parameters compared with the control group.

Industrial workers with occupational hand injury from Tehran factories.

OBJECTIVE: The aim of this study was evaluation of occupational and non-occupational risk factors in workers with occupational hand injury. PARTICIPANTS: Eighty-two workers with occupational hand injury as cases and 83 controls matched for age, gender and also occupation, were included in the study. Controls were chosen randomly from the same factories and the same jobs but they did not have occupational hand injury. METHODS: The study utilized a case control design for analysis. Working circumstances were assessed using a detailed occupational questionnaire as well as non-occupational factors. The questionnaire was completed for both cases and controls. Multivariate logistic regression modeling was used to test the association between occupational and non-occupational factors and hand injury. RESULTS: Risk factors for occupational hand injury were: rotational shift work, working in the early hours in the morning, working alone; and protective factors were: availability of safety equipment or having the equipment equipped with safety tools, safety education and using safety equipment. Adjusted for confounding factors, protective factors were: availability of safety equipment or having the equipment equipped with safety tools and the risk factor was working alone. CONCLUSION: Some occupational factors are protective and some increase risk for occupational hand injury. By modifying these factors we may decrease the prevalence of occupational hand injuries.

Association of occupational and non-occupational risk factors with the prevalence of work related carpal tunnel syndrome.

PURPOSE: Several occupational and personal risk factors cause the development of carpal tunnel syndrome (CTS). The purpose of the study was to evaluate both non-occupational and occupational factors associated with CTS in industrial workers. METHODS: A cross sectional study was designed with 400 industrial workers (77% male, 23% female) randomly selected. Workers' upper extremities were examined and related signs and symptoms were assessed. Questionnaires about personal and occupational risk factors were completed and suspicious cases were referred for NCV (nerve conduction velocity) testing and documentation of diagnosis. RESULTS: About 395 workers from automobile industry factories in Iran were assessed by interview and electrodiagnostic studies. Among 395 workers, 47 met the definition of CTS to yield a prevalence of 11.9%. These 47 workers averaged 29.85 years of age (SD = 6.28), and the mean age of the healthy group was 27.95 (SD = 4.86). 395 workers included 91 women (23%) and 304 men (77%). Using multivariate logistic regression model the largest adjusted odds ratios of personal and occupational factors for CTS were: exertion of force over one kilogram 6.38 (1.91-2.02); bending/twisting of the hands/wrists > 30 degrees , 5.62 (0.56-55.6); history of cigarette smoking 4.68 (1.80-11.80); rapid movement of hands 4.44 (1.41-14.02); and use of vibrating tools 3.23 (1.46-7.15). CONCLUSION: Some occupational factors including force exertion, bending/twisting of the hands, rapid movement of the hands and vibration are associated with CTS.

Hyperhomocysteinemia and central retinal vein occlusion in Iranian population.

PURPOSE: To evaluate total plasma homocysteine level during the acute phase of central retinal vein occlusion (CRVO) in the Iranian population and determine whether hyperhomocysteinemia is also a risk factor for CRVO. METHODS: Fifty-four patients with recently diagnosed CRVO were studied. Their fasting total plasma homocysteine level was compared with a matched control group of 51 patients evaluated in the same clinic for a non-retinal disease diagnosis. RESULTS: The mean total plasma homocysteine level was 14.76+/-7.67 micromol/l in cases, and 11.42+/-3.74 micromol/l in control subjects. It showed a significant difference (P=0.005) in mean plasma homocysteine level between cases and control group. Odds ratio of CRVO for individuals with hyperhomocysteinemia was 2.88 (95% CI=1.08-7.71 and P=0.03). The overall multivariable-adjusted odds of CRVO in participants with plasma homocysteine level above 15 micromol/l was 4.71 (95% CI=1.46-15.19 and P=0.009) Hyperhomocysteinemia was not statistically different in each age group (<60 years: 27%, 61-70 years: 33.3%, 71-80 years: 31.6%, >81 years: 33.3%, Chi-square test, P=0.98). CONCLUSION: Elevated total plasma homocysteine level is an independent risk factor for CRVO in Iranian population. In addition to an evaluation of all conventional cardiovascular risk factors, measurement of total homocysteine for evidence of hyperhomocysteinemia may be important in the initial investigation and management of patients with CRVO.