Effects of a sleep education program with self-help treatment on sleeping patterns and daytime sleepiness in Japanese adolescents: A cluster randomized trial

Subjective insufficient sleep and delayed sleep–wake patterns have been reported as the primary causes for daytime sleepiness, a reasonably significant and prevalent problem for adolescents worldwide. Systematic reviews have indicated that the success of sleep education programs has thus far been inconsistent, due to the lack of a tailored approach that allows for evaluation of individual differences in behavior patterns. One way to resolve this problem is to assess the individual sleep behaviors of adolescents by using a checklist containing the recommended behaviors for promoting sleep health. Such self-help education programs have already been implemented for elementary school children, school nurses and the elderly. The present study aimed to verify the effects of a sleep education program with supplementary self-help treatment, based on a checklist of sleep-promoting behaviors, in addition to evaluation of changes in sleeping patterns, sleep-promoting behaviors and daytime sleepiness in adolescents. A cluster randomized controlled trial involving 5 Japanese junior high schools was conducted, and 243 students (sleep education: n = 122; waiting list: n = 121; 50.6% female; 7th grade) were included in the final analysis. The sleep education group was provided with information on proper sleep health and sleep-promoting behaviors. The students in this group were asked to practice one sleep-promoting behavior as a goal for 2 weeks and to monitor their practice using sleep diaries. Both pre- and post-treatment questionnaires were administered to students in order to assess knowledge of sleep-promoting behaviors, sleeping patterns and daytime functioning. Students in the sleep education group showed significant improvement in their knowledge of sleep health (F_1,121 = 648.05, p < 0.001) and in their sleep-promoting behaviors (F_1,121 = 55.66, p < 0.001). Bedtime on both school nights (F_1,121 = 50.86, p < 0.001) and weekends (F_1,121 = 15.03, p < 0.001), sleep-onset latency (F_1,121 = 10.26, p = 0.002), total sleep time on school nights (F_1,121 = 12.45, p = 0.001), subjective experience of insufficient sleep (McNemar χ²(1) = 4.03, p = 0.045) and daytime sleepiness (McNemar χ²(1) = 4.23, p = 0.040) were also improved in the sleep education group. In contrast, no significant improvement in these variables was observed for students in the waiting-list group. In conclusion, the sleep education program with self-help treatment was effective not only in increasing sleep knowledge but also in improving sleep-promoting behavior and sleeping patterns/reducing daytime sleepiness for students in the sleep education group, in comparison with the waiting-list group.     

Sleep on the Job Partially Compensates for Sleep Loss in Night‐Shift Nurses

Nursing personnel in Brazil are usually submitted to fixed 12 h shifts with no consecutive working days or nights. Moonlighting is common in this group, with a consequent increase in the number of working hours. The possibility of sleeping on the job during the night shift in the studied hospitals had already been described. The present study aims to analyze whether the time devoted to daily activities (sleep, rest, leisure, housework, commuting, personal needs, care of children or other people, non‐paid work, and study) is related to the number of worked hours and to nap‐taking during the night shift. The field study took place at two public hospitals in Rio de Janeiro, Brazil. Workers filled out a structured form on time devoted to the above‐mentioned activities for at least four consecutive days. The time devoted to sleep was analyzed according to its occurrence at home or on the job. Workers were classified according to the number of jobs (one job/two jobs) and the time dedicated to work according to the median of the whole series (below the median/above the median). All workers who had at least one working night were analyzed as to nap‐taking on the job. They were classified according to the sleep occurrence during the night shift—the sleep group and the non‐sleep group, both of which were compared to daytime workers. Statistical treatment of data included non‐parametrical procedures. The study group comprised 144 workers (mean age: 35.7±10.5 years old; 91% women; 78% nurse assistants, the remainder registered nurses). They recorded their daily activities for 4–11 days; 829 cumulative days were analyzed for the whole group. A total of 165 working nights were analyzed; sleep or rest occurred during 112 (68%) of them, with mean sleep/rest duration of 141±86 min. Time devoted to sleep and leisure varied according to the number of working hours, being significantly reduced in those submitted to longer work hours (p<0.001 and p=0.002, respectively). Results close to significance point to a reduction in the time dedicated to housework among workers with long work hours (p=0.053). The time spent on sleep/rest per working night did not differ according to the number of worked hours (p=0.490). A tendency was observed for those who have two jobs to devote more time to sleep/rest on the job (p=0.058). The time of personal needs was significantly lower among those who did not sleep on the job as compared to day workers (p=0.036). The total sleep time was significantly lower among those who did not sleep on the job, as compared to day workers and to those who slept on the job (p=0.004 and p=0.05, respectively). As to home sleep length, workers who slept and those who did not sleep on the job were similar and slept significantly less than exclusively daytime workers (p<0.001 and p=0.002, respectively). Sleeping on the job during the night shift seems to partially compensate for the shorter sleep at home among night workers and may play a beneficial effect in coping with two jobs.     

Association between depressive symptoms and morningness-eveningness,sleep duration and rotating shift work in Japanese nurses

Higher depressive symptoms have been reported in rotating shift workers compared with day workers. Depressive symptoms in adults who do not engage in night work have also been shown to be associated with chronotype and sleep duration. This study examines associations between depressive symptoms, morningness-eveningness (i.e. the degree to which people prefer to be active in the morning or the evening), sleep duration and rotating shift work. Japanese nurses (1252 day workers and 1780 rotating shift workers, aged 20–59) were studied using a self-administered questionnaire. The questionnaire covered depressive symptoms, morningness-eveningness, sleep habits and demographic characteristics of the participants. The Center for Epidemiologic Studies Depression Scale (CES-D) was used to determine the levels of depressive symptoms. A Japanese version of the Morningness-Eveningness Questionnaire (MEQ) was used to measure morningness-eveningness. The CES-D score of shift workers was significantly (p < 0.05) higher than that of day workers. The MEQ score was significantly (p < 0.05) lower (i.e. greater eveningness) in shift workers than in day workers. Sleep duration on the day shift was significantly (p < 0.05) shorter in shift workers than in day workers. Simple linear regression revealed that the MEQ score, sleep duration on the day shift and current work shift (i.e. rotating shift work) were significantly (p < 0.05) associated with the CES-D score. Multivariate linear regression indicated that greater eveningness and shorter sleep duration were independently associated with higher CES-D scores, while rotating shift work was not. These associations between the MEQ score, the sleep duration and the CES-D score were also confirmed in both day workers and shift workers when the groups were analyzed separately. These results suggest that greater eveningness and shorter sleep duration on the day shift were independently associated with higher levels of depressive symptoms, which may explain associations between rotating shift workers and depressive symptoms. These findings have important implications for the development of novel strategies for preventing poor mental health in day workers and rotating shift workers.     

Sleep duration,nightshift work,and the timing of meals and urinary levels of 8-isoprostane and 6-sulfatoxymelatonin in Japanese women

It has been hypothesized that disruption of circadian rhythms affects human health. Shift work and sleep deprivation are thought to disrupt the normal light–dark cycle, although the disruption due to shiftwork may be dependent on sleep deprivation. Both conditions have been suggested to be associated with an increased risk of cardiometabolic disorders. Non-photic environmental factors, such as the timing of eating, are also thought to regulate circadian rhythm and thus, may have effects on health, but the evidence from human studies is scarce. Oxidative stress is a risk factor of cardiometabolic disorders. Some laboratory studies suggest an involvement of circadian clock genes in the regulation of the redox system. The present study aimed to examine the association of sleeping habits, nightshift work, and the timing of meals with urinary levels of 8-isoprostane, a marker of oxidative stress, and 6-sulfatoxymelatonin, the principal metabolite of melatonin. Study subjects were 542 women who had previously attended a breast cancer mass screening in a community in Japan. Information on bedtimes and wake-up times, history of nightshift work, and the timing of meals was obtained by a self-administered questionnaire. The 8-isoprostane and 6-sulfatoxymelatonin were measured using the first morning void of urine and expressed per mg of creatinine. The geometric mean of 8-isoprostane levels was 12.1% higher in women with ≤6 hours of sleep than that in those with >8 hours of sleep on weekdays, and longer sleep duration on weekdays was significantly associated with lower urinary levels of 8-isoprostane after controlling for covariates (p for trend = 0.04). Women who were currently working the nightshift had a 33.3% higher geometric mean of 8-isoprostane levels than those who were not working nightshift (p = 0.03). Urinary 6-sulfatoxymelatonin levels were unrelated to sleep habits or nightshift work. Women who ate breakfast at irregular times had a 19.8% higher geometric mean of 8-isoprostane levels than those who ate breakfast at a regular time or who did not eat (p = 0.02). Women who ate nighttime snacks at irregular times had a 16.2% higher geometric mean of 8-isoprostane levels than those who did not eat nighttime snacks or who ate nighttime snacks at a regular time (p = 0.003). Among women who ate dinner at a regular time, earlier times for dinner were associated with higher 8-isoprostane and 6-sulfatoxymelatonin levels (p values for trends were 0.01 and 0.02, respectively). However, the times of dinner and nighttime snack are overlapping, and the time of last meal of the day was not associated with 8-isoprostane and 6-sulfatoxymelatonin levels. The time of breakfast or lunch was not associated with these biomarkers among women who ate the meal at regular times. Disturbing the rhythmicity of daily life may be associated with oxidative stress.     

Individual differences in the sleep/wake cycle of Arctic flexitime workers

Daytime workers tend to have shorter sleep duration and earlier sleep onset during work days than on days off. Large individual differences in sleep onset and sleep duration may be observed on work days, but work usually synchronizes sleep offset to a similar time. The present study describes individual differences in sleep behaviour of 48 daytime workers (25 men, aged 20–58 years) from an iron ore mine in Northern Sweden. The aim of the study was to determine whether differences in sleep patterns during work days were associated with the outcomes of sleepiness and sleep complaints. Cluster analysis was used to group workers into two categories of sleep onset and sleep duration. The “Late Sleep Onset” cluster comprised workers who slept 1.30 h later than the “Early Sleep Onset” cluster (p < 0.0001 for all weekdays). The “Long Sleep Duration” cluster slept 1.10 h longer than the “Short Sleep Duration” cluster (p < 0.0002 for work nights). The “Late Sleep Onset” cluster reported less refreshing sleep (p < 0.01) and had lower sufficient sleep scores (p < 0.01) than the “Early Sleep Onset” cluster. The “Short Sleep Duration” cluster also reported lower scores for sufficient sleep (p < 0.04) than the “Long Sleep Duration” cluster. For combined characteristics (phase and duration), workers with a late phase and short sleep duration reported greater sleep debt and sleepiness than workers with an early phase and short sleep duration (p < 0.02). Work schedule and commuting time modulate both sleep phase and sleep duration independently. Workers, classified as having an intermediate sleep phase preference, can organize their sleep time in order to minimize sleep debt and sleepiness symptoms. Individual differences in sleep phase and duration should be considered when promoting well-being at work even among groups with similar sleep needs. In order to minimize sleep debt and sleepiness symptoms, successful sleep behaviour could be promoted involving extend use of flexitime arrangement (i.e. later starting times) and reduce use of alarm clocks.     

IMPLEMENTATION OF 12-HOUR SHIFTS IN A BRAZILIAN PETROCHEMICAL PLANT: IMPACT ON SLEEP AND ALERTNESS

A recent worldwide trend in chemical and petrochemical industries is to extend the duration of shifts. Optimization of the labor force to reduce costs is one reason to increase the length of working time in a shift. Implementation of 12h shifts is a controversial decision for managers and scientists. Literature reviews show alertness is lower during the nighttime hours, and sleep duration is reduced and worse during the daytime. The main objective of this study was to evaluate the impacts of 12h shifts on alertness and sleep. To evaluate the duration and quality of sleep and alertness during work, 22 male shift workers on a continuous rotating schedule at a petrochemical plant completed activity logs and estimated alertness using analog 10-cm scales for 30 consecutive days, three times (at 2h, 6h, and 10h of the shift) every work shift. Statistical tests (analysis of variance [ANOVA] and Tukey) were performed to detect differences between workdays and off days. The shift schedule was 2 days/3 nights/4 off days, followed by 3 days/2 nights/5 off days, followed by 2 days/2 nights/5 off days. Sleep duration varied significantly (p <. 001) among the work shifts and off days. Comparing work nights, the shortest mean sleep occurred after the second night (mean = 311.4 minutes, SD = 101.7 minutes), followed by the third night (mean = 335.3 minutes, SD = 151.2 minutes). All but one shift (sleep after the first work night) were significantly different from sleep after the first 2 workdays (p <. 002). Tukey tests showed no significant differences in sleep quality between workdays and nights, with the exception of sleep after the third day compared to sleep after night shifts. However, significant differences were detected between off days and work nights (p <. 01). ANOVA analysis showed borderline differences among perceived alertness during day shifts (p =. 073) and significant differences among the hours of theshifts(p =. 0005), especially when comparing the 2nd hour of the first day with the 10th hour of all the day shifts. There were no significant differences in perceived alertness during night work among the first, second, and third nights (p =. 573), but there were significant differences comparing the times (2nd, 6th, 10th hour) of the night shifts (p ≤. 001). The evaluation of sleep (duration and quality) and level of alertness have been extensively used in the literature as indicators of possible performance decrements at work. The results of this study show poorer sleep after and significantly decreased alertness during night work. Shifts of 12h are usually implemented for technical and economic reasons. These results point out the necessity of a careful trade-off between the financial and technical gains longer shifts might bring and the possible losses due to incidents or accidents from performance decrements during work. (Chronobiology International, 17(4), 521–537, 2000)     

Late chronotype and high social jetlag are associated with burnout in evening-shift workers: Assessment using the Chinese-version MCTQshift

Chronotypes are associated with shift work tolerance and sleep in shift workers, and sleep mediates the impact of shift work on mental health. However, the role of chronotype in the association between shift work and mental health has not been clarified. In this study, we aimed to examine the association between chronotype and burnout in shift workers, using the validated Munich ChronoType Questionnaire for shift workers (MCTQ^shift). A total of 288 shift workers with irregular shift frequencies were recruited and completed the Chinese-version MCTQ^shift and the Morningness–Eveningness Questionnaire (MEQ). Chronotypes were assessed by the calculation of corrected mid-sleep time (MSF_SC) from mid-sleep time on free days (MSF) based on their exact shift schedules. Another 26 evening-shift nurses were monitored with actigraphy for at least two consecutive evening shifts and the following two free days. Burnout was evaluated using the Copenhagen Burnout Inventory. We found that MSF^E_SC, MSF^E and mid-sleep time on workdays (MSW^E) had normal distributions and correlated significantly with MEQ scores (r = ? 0.47, ?0.45 and ?0.47, respectively; all p < 0.001). MSW was more closely correlated with actigraphy-derived mid-sleep time on the free day before workdays than that on workdays (r = 0.61 and 0.48, respectively, p < 0.05). Sleep duration was significantly longer on workdays among evening-shift workers who slept late on workdays than those who slept early (β = 0.59, p < 0.001). After demographic and work characteristics were adjusted for in linear regression models, late chronotype and high social jetlag were associated with burnout scores in evening-shift workers. In conclusion, the Chinese-version MCTQ^shift is a valid tool for chronotype assessment. Interventions to improve sleep in shift workers should be tailored to chronotype due to variations in sleep behavior. Late chronotype may be an inherent feature of mental health problems, because the association with burnout was significant in both day workers in previous studies and shift workers.     

Differences in circadian phase and weekday/weekend sleep patterns in a sample of middle-aged morning types and evening types

Factors contributing to sleep timing and sleep restriction in daily life include chronotype and less flexibility in times available for sleep on scheduled days versus free days. There is some evidence that these two factors interact, with morning types and evening types reporting similar sleep need, but evening types being more likely to accumulate a sleep debt during the week and to have greater sleep extension on weekend nights. The aim of the present study was to evaluate the independent contributions of circadian phase and weekend-to-weekday variability to sleep timing in daily life. The study included 14 morning types and 14 evening types recruited from a community-based sample of New Zealand adults (mean age 41.1 ± 4.7 years). On days 1–15, the participants followed their usual routines in their own homes and daily sleep start, midpoint and end times were determined by actigraphy and sleep diaries. Days 16–17 involved a 17 h modified constant routine protocol in the laboratory (17:00 to 10:00, <20 lux) with half-hourly saliva samples assayed for melatonin. Mixed model ANCOVAs for repeated measures were used to investigate the independent relationships between sleep start and end times (separate models) and age (30–39 years versus 40–49 years), circadian phase [time of the dim light melatonin onset (DLMO)] and weekday/weekend schedules (Sunday–Thursday nights versus Friday–Saturday nights). As expected on weekdays, evening types had later sleep start times (mean = 23:47 versus 22:37, p < .0001) and end times (mean = 07:14 versus 05:56, p < .0001) than morning types. Similarly on weekend days, evening types had later sleep start times (mean = 00:14 versus 23:07, p = .0032) and end times (mean = 08:56 versus 07:04, p < .0001) than morning types. Evening types also had later DLMO (22:06 versus 20:46, p = .0002) than morning types (mean difference = 80.4 min, SE = 18.6 min). The ANCOVA models found that later sleep start times were associated with later DLMO (p = .0172) and weekend-to-weekday sleep timing variability (p < .0001), after controlling for age, while later sleep end times were associated with later DLMO (p = .0038), younger age (p = .0190) and weekend days (p < .0001). Sleep end times showed stronger association with DLMO (for every 30 min delay in DLMO, estimated mean sleep end time occurred 14.0 min later versus 10.19 min later for sleep start times). Sleep end times also showed greater delays on weekends versus weekdays (estimated mean delay for sleep end time = 84 min, for sleep start time = 28 min). Comparing morning types and evening types, the estimated contributions of the DLMO to the mean observed differences in sleep timing were on weekdays, 39% for sleep start times and 49% for sleep end times; and on weekends, 41% for sleep start times and 34% of sleep end times. We conclude that differences in sleep timing between morning types and evening types were much greater than would be predicted on the basis of the independent contribution of the difference in DLMO on both weekdays and weekend days. The timing of sleep in daily life involves complex interactions between physiological and psychosocial factors, which may be moderated by age in adults aged 30–49 years.     

Bullying,sleep/wake patterns and subjective sleep disorders: Findings from a cross-sectional survey

The aim of this study was to explore: (a) sleep patterns and disorders possibly associated with adolescent bullying profiles (pure bully, pure victim, bully/victim and neutral) and (b) the effect of sleep on psychosocial problems (externalized and internalized) related to bullying. The sample consisted of 1422 students aged 10–18 (mean?=?14.3, SD?=?2.7; 57% male) from five socioeconomically diverse schools in France. Bullying profiles were obtained using the revised Bully–Victim Questionnaire. Subjective sleep disorders were assessed using the Athens Insomnia Scale. School-week and weekend sleep/wake patterns were recorded. Internalizing problems were investigated using a Perceived Social Disintegration Scale and a Psychological Distress Scale. Externalizing behaviors were assessed using a General Aggressiveness Scale and an Antisocial Behavior Scale. These questionnaires were administered during individual interviews at school. After controlling for effects of gender and age, victims of bullying showed significantly more subjective sleep disturbances than the pure-bully or neutral groups (p?<?0.001). Bullies’ sleep schedules were more irregular (p?<?0.001 for bedtime irregularity and p<0.01 for wake-up time irregularity) and their sleep duration was shorter than their schoolmates (p?<?0.001 for the school week and p?<?0.05 for the weekend). There was an effect of sleep on psychosocial problems related to bullying, and our results indicate that sleep has a moderating effect on aggression in bullies (p?<?0.001). This would suggest a higher vulnerability of bullies to sleep deprivation. These results show differences in sleep problems and patterns in school-bullying profiles. Findings of this study open up new perspectives for understanding and preventing bullying in schools, with implications for research and clinical applications.     

Shift work and sleep disorder comorbidity tend to go hand in hand

Taking into consideration that shift work has a wide-ranging impact on circadian and sleep functioning, it seems likely that shift work increases the risk of a general sleep disturbance, spread out over a multitude of comorbid sleep disorders. The aim of the present study is to analyze and present the sleep disorder data of 250 shift workers and 971 permanent day workers, taken from a nationally representative sample. Additional data concerning duration, timing, and quality of sleep, daytime functioning and social/family variables were added to the analyses. The results showed that the shift workers experienced significantly more difficulties with the variability of their sleep times, reported more napping and considered themselves more as poor sleepers than the day workers. Most importantly, shift work, in comparison with day work, appeared associated with a significantly higher prevalence of the clinical, International Classification of Sleep Disorders’ defined symptoms of nearly all main sleep disorders (including shift work disorder). For shift workers, the prevalence of a general sleep disturbance was 39.0% (95%CI 33.2 – 45.2), significantly higher than for day workers (24.6%, 95%CI 22.0 – 27.4). Moreover, shift workers were characterized by high levels of sleep disorder comorbidity. In addition, exclusively for shift workers, the prevalence of disordered sleep systematically decreased across decades of life and was considerably higher for single versus partnered shift workers. This study adds to the insight into the interacting factors that determine shift work coping and may play a role in occupational health interventions aimed at reducing sleep problems and thus improving the resilience and tolerance of the shift worker.     

Sleep quality and methylation status of core circadian rhythm genes among nurses and midwives

Poor sleep quality or sleep restriction is associated with sleepiness and concentration problems. Moreover, chronic sleep restriction may affect metabolism, hormone secretion patterns and inflammatory responses. Limited recent reports suggest a potential link between sleep deprivation and epigenetic effects such as changes in DNA methylation profiles. The aim of the present study was to assess the potential association between poor sleep quality or sleep duration and the levels of 5-methylcytosine in the promoter regions of PER1, PER2, PER3, BMAL1, CLOCK, CRY1 CRY2 and NPAS2 genes, taking into account rotating night work and chronotype as potential confounders or modifiers. A cross-sectional study was conducted on 710 nurses and midwives (347 working on rotating nights and 363 working only during the day) aged 40–60 years. Data from in-person interviews about sleep quality, chronotype and potential confounders were used. Sleep quality and chronotype were assessed using Pittsburgh Sleep Quality Questionnaire (PSQI) and Morningness–Eveningness Questionnaire (MEQ), respectively. Morning blood samples were collected. The methylation status of the circadian rhythm genes was determined via quantitative methylation-specific real-time PCR assays (qMSP) reactions using DNA samples derived from leucocytes. The proportional odds regression model was fitted to quantify the relationship between methylation index (MI) as the dependent variable and sleep quality or sleep duration as the explanatory variable. Analyses were carried out for the total population as well as for subgroups of women stratified by the current system of work (rotating night shift/day work) and chronotype (morning type/intermediate type/evening type). A potential modifying effect of the system of work or the chronotype was examined using the likelihood ratio test. No significant findings were observed in the total study population. Subgroup analyses revealed two statistically significant associations between a shorter sleep duration and 1) methylation level in PER2 among day workers, especially those with the morning chronotype (OR = 2.31, 95%CI:1.24–4.33), and 2) methylation level in CRY2 among subjects with the intermediate chronotype, particularly among day workers (OR = 0.52, 95%CI:0.28–0.96). The study results demonstrated a positive association between average sleep duration of less than 6 hours and the methylation level of PER2 among morning chronotype subjects, and an inverse association for CRY2 among intermediate chronotype subjects, but only among day workers. Both the system of work and the chronotype turned out to be important confounders and modifiers in a number of analyses, making it necessary to consider them as potential covariates in future research on sleep deficiency outcomes. Further studies are warranted to explore this under-investigated topic.     

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.     

Shift-specific associations between age,chronotype and sleep duration

The objective of this study was to examine the association of age with chronotype and sleep duration in day workers and rotating shift workers, including night shift work. Between October 2012 and February 2015, a cross-sectional study was conducted in a German chemical company. Using the “Munich ChronoType Questionnaire” (MCTQ), data about sleep onset and sleep offset during workdays and work-free days were retrieved and the chronotype was computed during regular voluntary occupational health check-ups. Associations between age and chronotype, as well as sleep duration, were assessed using linear regression analyses. Potential effect modification by the working time system was examined. Within the study period, 4,040 employees (82.3% and 17.7% were engaged in day work and rotating shift work, respectively) completed the questionnaire. Study participants were on average 41.8 years old (Min = 18.0, Max = 65.0, SD = 10.2) and predominantly male (75.4%). Mean chronotype and overall sleep duration was 03:22 (SD = 54 min) and 7.2 h (SD = 1.0 h) respectively. Older age was associated with earlier chronotype and reduced overall sleep duration in both day workers and rotating shift workers (p < 0.001 for all models). Compared to day workers, employees whom engaged in rotating shift work were later chronotypes and had overall a longer sleep duration. With older age, the difference between day and rotating shift workers regarding chronotype increased, while the difference regarding overall sleep duration decreased (p_interaction<0.005 for both models). This finding could indicate that both changes in circadian physiology and exposure to certain work schedules contribute to the age-related changes. Older rotating shift workers, with early chronotypes may have issues with night shifts, while day work and morning shifts may be best compatible to earlier chronotypes. Differences in sleep timing across age groups, might indicate that the same work hours will affect shift workers differently, dependent on their age, suggesting that more flexible and chronotype-adapted work hours could provide useful; especially for older employees. Sleep education in the form of courses and health campaigns could be a way to raise awareness of the importance of a healthy sleep pattern. This could be achieved by learning strategies to better adjust individual sleep patterns to work hours.     

Perceived sleep quality among edentulous elders

doi: 10.1111/j.1741‐2358.2010.00426.x Perceived sleep quality among edentulous elders Background: Anatomical changes associated with edentulism are thought to disturb seniors’ sleep. Objectives: (1) To determine sleep quality and daytime sleepiness of edentulous elders. (2) To examine the association between oral health‐related quality of life and sleep quality. Methods: Data were collected at a 1‐year follow‐up from 173 healthy edentulous elders who had participated in a randomised controlled trial and randomly received two types of mandibular prosthesis. Subjective sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI, range 0–21), with higher scores indicating poorer sleep quality. The Epworth Sleepiness Scale (ESS) was used to measure the level of perceived daytime sleepiness, and scores ≥10 indicated sleepiness. Results: The mean global PSQI and ESS scores were 4.7 ± 3.5 and 5.3 ± 3.9. There were no differences in sleep quality or sleepiness between those who wore their dentures at night and those who did not. Elders with frequent denture problems were sleepier during the day than those with fewer problems (p = 0.0034). General health (p = 0.02) and oral health‐related quality of life (p = 0.001) are significant predictors of sleep quality. Conclusion: Healthy edentulous elders, independent of nocturnal wearing of their prosthesis, are good sleepers. Maintaining high oral health quality of life could contribute to better sleep.     

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.     

Relationship between shift work schedule and self-reported sleep quality in Chinese employees

Few studies have reported on the effects of fixed and rotating shift systems on the prevalence of sleep disturbance. Thus, in this study, the relationships between different work schedules and sleep disturbance in Chinese workers were investigated. A total of 2180 workers aged 19–65 years responded to the self-report questionnaire on shift work schedule (fixed day-shift, fixed night-shift, two-shift or three-shift system), working hours a day, and working days a week, physical effort, subjective sleep quality and subjective mental state. It was found that the rotating shift workers, namely, two- and three-shift workers, exhibited higher risks of sleep disturbance than with the fixed day-shift workers did (OR 1.37; 95% CI 1.07to 1.74; and OR 2.19; 95% CI 1.52 to 3.15, respectively). The risk was particularly high among two- or three-shift workers who worked more than 8 hours a day or more than 5 days a week and among three-shift workers who reported both light and heavy physical effort at work. Moreover, the two- and three-shift workers (rotating shift workers) suffered from poorer sleep quality than the fixed night shift workers did (OR 1.84; 95% CI 1.01 to 3.32; and OR 2.94; 95% CI 1.53 to 5.64, respectively). Consequently, rotating shift work (two- and three-shift work) is a risk factor for sleep disturbance, and the fixed work rhythm may contribute to the quality of sleep.     

Outdoor artificial light at night,obesity, and sleep health: Cross-sectional analysis in the KoGES study

Obesity is a common disorder with many complications. Although chronodisruption plays a role in obesity, few epidemiological studies have investigated the association between artificial light at night (ALAN) and obesity. Since sleep health is related to both obesity and ALAN, we investigated the association between outdoor ALAN and obesity after adjusting for sleep health. We also investigated the association between outdoor ALAN and sleep health. This cross-sectional survey included 8526 adults, 39–70 years of age, who participated in the Korean Genome and Epidemiology Study. Outdoor ALAN data were obtained from satellite images provided by the US Defense Meteorological Satellite Program. We obtained individual data regarding outdoor ALAN; body mass index; depression; and sleep health including sleep duration, mid-sleep time, and insomnia; and other demographic data including age, sex, educational level, type of residential building, monthly household income, alcohol consumption, smoking status and consumption of caffeine or alcohol before sleep. A logistic regression model was used to investigate the association between outdoor ALAN and obesity. The prevalence of obesity differed significantly according to sex (women 47% versus men 39%, p < 0.001) and outdoor ALAN (high 55% versus low 40%, p < 0.001). Univariate logistic regression analysis revealed a significant association between high outdoor ALAN and obesity (odds ratio [OR] 1.24, 95% confidence interval [CI] 1.14–1.35, p < 0.001). Furthermore, multivariate logistic regression analyses showed that high outdoor ALAN was significantly associated with obesity after adjusting for age and sex (OR 1.25, 95% CI 1.14–1.37, p < 0.001) and even after controlling for various other confounding factors including age, sex, educational level, type of residential building, monthly household income, alcohol consumption, smoking, consumption of caffeine or alcohol before sleep, delayed sleep pattern, short sleep duration and habitual snoring (OR 1.20, 95% CI 1.06–1.36, p = 0.003). The findings of our study provide epidemiological evidence that outdoor ALAN is significantly related to obesity.     

Efficient and Regular Patterns of Nighttime Sleep are Related to Increased Vulnerability to Microsleeps Following a Single Night of Sleep Restriction

Sleep-deprived people, or those performing extended monotonous tasks, can exhibit brief episodes in which they suspend performance and appear to fall asleep momentarily—behavioral microsleeps (“microsleeps”). In this study, microsleeps were identified using eye video and tracking response during a 20-min continuous tracking task undertaken by 16 healthy volunteers (mean age 24.9?yrs; 8 females, 8 males) in the early afternoon following a normally rested night and a night of restricted sleep (time-in-bed restricted to 4?h). Sessions were 1 wk apart and counterbalanced. Wrist actigraphy, self-reported sleepiness, and sleep quality were also recorded. We hypothesized that high microsleep rates when normally rested or after a night of sleep restriction would be related to poor sleep quality, sleep disturbance, circadian type, irregular sleep patterns, low daily sleep duration, or poor sleep efficiency. We also hypothesized that prior performance on a 10-min psychomotor vigilance task (PVT) (mean reaction time or number of PVT lapses) would be related to the number of microsleeps during the tracking task and that PVT performance could, therefore, be used as a fitness-for-duty indicator. The number of microsleeps during the tracking task increased following sleep restriction (mean 11.4 versus 27.9; p?=?0.03). There were no correlations between the number of microsleeps in the normally rested session and any of the actigraphically measured or self-reported sleep measures. However, the number of microsleeps following sleep restriction was correlated with sleep efficiency (r?=?0.73, p?=?0.001), sleep onset latency (r?=??0.57, p?=?0.02), and sleep onset time-of-day standard deviation (r?=??0.54, p?=?0.03) over 11 normally rested nights. There was no correlation between PVT performance and the subsequent number of microsleeps during the tracking task in either session. Attributes usually associated with beneficial nighttime sleep patterns—going to sleep at a similar time each night, falling asleep quickly, and infrequent arousals—were related to greater vulnerability to microsleeps following sleep restriction. There were intercorrelations between all the sleep measures associated with microsleep rate following sleep restriction, indicating that the measures form a pattern of behaviors and are not independently related to microsleep rate. Perhaps some people maintain a regular sleep pattern because they experience sleepiness the following day when their pattern is disrupted. Conversely, people with more variation in their sleep pattern may do so because this does not substantially increase sleepiness the following day. We conclude that people with consistent sleep patterns and efficient sleep may be more prone to microsleeps than other people when their usual regular pattern is disrupted by sleep restriction.     

Factors associated with sleep duration in Brazilian high school students

The aim of this study was to investigate the factors associated with short sleep duration on southern Brazilian high school students. Our study was comprised of 1,132 adolescents aged 14 to 19 years, enrolled in public high schools in São José, Brazil. The students answered a questionnaire about working (work and workload), health perception, smoking, school schedule, sleep (duration and daytime sleepiness), and socio-demographics data. The results showed that more than two thirds of adolescent workers had short sleep duration (76.7%), and those with a higher workload (more than 20 hours) had a shorter sleep duration (7.07 hours) compared to non-workers (7.83 hours). In the analysis of factors associated with short sleep duration, adolescents who worked (OR = 2.12, 95% CI 1.53 to 2.95) were more likely to have short sleep duration compared to those who did not work. In addition, older adolescents (17–19 years) and students with poor sleep quality were 40% and 55% more likely to have short sleep duration compared to younger adolescents (14–16 years) and students with good sleep quality, respectively. Adolescents with daytime sleepiness were more likely to have short sleep duration (OR = 1.49, 95% CI 1.06 to 2.07) compared to those without excessive daytime sleepiness. In addition students of the morning shift (OR = 6.02, 95% CI 4.23 to 8.57) and evening shift (OR = 2.16, 95% CI 1.45 to 3.22) were more likely to have short sleep duration compared to adolescents of the afternoon shift. Thereby adolescents who are workers, older, attended morning and evening classes and have excessive daytime sleepiness showed risk factors for short sleep duration. In this sense, it is pointed out the importance of raising awareness of these risk factors for short sleep duration of students from public schools from São José, located in southern Brazil.     

The impact of shift starting time on sleep duration,sleep quality,and alertness prior to injury in the People’s Republic of China

Early shift start time and night shifts are associated with reduced sleep duration and poor sleep quality that often lead to increased fatigue levels, performance decrements and adverse safety and health outcomes. This study investigates the impact of shift starting time on sleep patterns, including the duration and quality of sleep and alertness/sleepiness at the time of injury, in a large epidemiological field study of hospitalized adults with severe work-related hand injury in the People’s Republic of China (PRC) from multiple industries with severe work-related traumatic hand injury were recruited from 11 hospitals in three industrially-developed cities in the PRC: Ningbo, Liuzhou and Wuxi. Analysis of covariance (ANCOVA) was used to compare sleep duration, sleep quality and alertness/sleepiness across 3?h increments of shift start time, while adjusting for age, gender, work hours, shift duration, day of injury and several transient work-related factors. Effect modification by gender was also evaluated. Seven-hundred and three hospitalized adults (96.4%) completed a face-to-face interview within 4 days of injury; 527 (75.0%) were male, with a mean (±SEM) age of 31.8?±?0.4 years. Overall, these adults worked relatively long weekly (55.7?±?0.6?h) and daily hours (8.6?±?0.07?h). Average sleep duration prior to injury was 8.5?h (±0.07), and showed significant variations (p value <0.05) across shift starting time increments. Overall mean prior sleep duration was shortest for individuals starting shifts from “21:00–23:59” (5.6±0.8?h) followed by midnight “00:00–02:59” (6.1?±?0.6?h). However, a statistically significant interaction (p?<?0.05) was observed between gender and shift starting time on mean sleep duration. For males the shortest sleep duration was 5.6?h (“21:00–23:59”) and for females the shortest was 4.3?h (“24:00–02:59” and “15:00–17:59”). Sleep quality (generally quite well) and alertness/sleepiness based on the KSS (generally alert) did not vary significantly across shift starting time. Results suggest that sleep duration is shortest among injured PRC adults starting shifts late night and early morning. However, with more than 8.5?h of sleep on average work days, Chinese slept much longer than typical US day workers (Sleep in America Poll, 2012, 6:44 on workdays, 7:35 on free days), and this may help to explain higher than expected alertness/sleepiness scores at the time of injury.