Subjective Sleep Quality Exclusively Mediates the Relationship Between Morningness-Eveningness Preference and Self-Perceived Stress Response

Eveningness preference has been associated with lower sleep quality and higher stress response compared with morningness preference. In the current study, female morning (n?=?27) and evening (n?=?28) types completed the Pittsburgh Sleep Quality Index (PSQI) and were additionally challenged with an arithmetic stress-induction task. Evening types reported lower subjective sleep quality and longer sleep latency than morning types. Furthermore, evening types reported higher self-perceived stress after the task than morning types. Subjective sleep quality fully mediated the relationship between morningness-eveningness preference and stress response. Poor sleep quality may, therefore, contribute to the elevated health risk in evening types. (Author correspondence: karolin.roeser@uni-wuerzburg.de)     

Circadian phase preference in college students: relationships with psychological functioning and academics

The current study offers a comprehensive assessment of psychosocial functioning and academic performance in relation to circadian phase preference in a US sample of undergraduate college students (N?=?838), aged 17-26 (M?=?19.78, SD?=?1.89). Women had greater morning preference than men, and seniors had greater morning preference than freshmen. Circadian phase preference, fatigue, perceived stress, depression, anxiety, and substance use were assessed cross-sectionally and grade point average (GPA) was assessed prospectively. Evening phase preference was related to higher levels of fatigue, alcohol and caffeine use, and worse academic performance than morning or intermediate phase preferences.     

Class Start Times,Sleep, and Academic Performance in College: A Path Analysis

Path analysis was used to examine the relationship between class start times, sleep, circadian preference, and academic performance in college-aged adults. Consistent with observations in middle and high school students, college students with later class start times slept longer, experienced less daytime sleepiness, and were less likely to miss class. Chronotype was an important moderator of sleep schedules and daytime functioning; those with morning preference went to bed and woke up earlier and functioned better throughout the day. The benefits of taking later classes did not extend to academic performance, however; grades were somewhat lower in students with predominantly late class schedules. Furthermore, students taking later classes were at greater risk for increased alcohol consumption, and among all the factors affecting academic performance, alcohol misuse exerted the strongest effect. Thus, these results indicate that later class start times in college, while allowing for more sleep, also increase the likelihood of alcohol misuse, ultimately impeding academic success. (Author correspondence: sonyper@stlawu.edu)     

EARLY MORNING WORK—PREVALENCE AND RELATION TO SLEEP/WAKE PROBLEMS: A NATIONAL REPRESENTATIVE SURVEY

Very little is known about the prevalence of morning work and its relationship with sleep and fatigue. The present study obtained data from a representative sample of the Swedish population (N?=?5489) to address this limitation in the literature. The results show that 15% of the population commenced work, at least occasionally, before 05:30?h and ～2% did so most of the time. With the increasing phase advance of the start time, the time of rising also advanced, but bedtime changed very little. Thus, early start times were not compensated with earlier bedtimes. Total sleep time decreased as the work start time was advanced; sleep duration was <5?h for work start times between 03:00 and 04:30?h. The results also indicated that advanced start times were linked with increased fatigue, feelings of not being well rested, and reports of early start times as a rather large or very large problem. However, difficulties in waking and disturbed sleep did not change with advanced start times. It was concluded that early start times are common and are associated with sleep problems and fatigue. (Author correspondence: torbjorn.akerstedt@stress.su.se)     

Health-Related Quality of Life in Adolescent Chronotypes—A Model for the Effects of Sleep Problems,Sleep-Related Cognitions,and Self-efficacy

In adolescence, the circadian preference shifts toward eveningness orientation. Eveningness seems to be negatively correlated with quality of life. The present study investigates influencing factors of this association and proposes a model for the mediating effects of sleep, sleep-related cognitions, and self-efficacy according to chronotype. The sample comprised N?=?280 adolescents (172 girls) aged 14–16 yrs (mean?=?15.19, SD?=?.76). Circadian preference, health-related quality of life (HRQoL), sleep disturbances, sleep-related dysfunctional cognitions, and general perceived self-efficacy were assessed online. Morning-orientated adolescents reported significantly higher HRQoL and less insomnia symptoms compared with evening-oriented chronotypes. In the total sample, insomnia symptoms mediated the relationship of chronotype and HRQoL. The strongest predictor of HRQoL in evening types was the degree of sleep-related dysfunctional cognitions. HRQoL in morning types was most strongly predicted by general self-efficacy, i.e., the global confidence in coping abilities. The findings support a negative relationship of eveningness and HRQoL in adolescents. Insomnia symptoms were identified to be mediating factors in this relationship. The influence of the mediating factors on HRQoL differed between morning and evening types. The model provides implications of how to enhance HRQoL in adolescents according to their circadian preference. (Author correspondence: karolin.roeser@uni-wuerzburg.de)     

Circadian Typology and Sensation Seeking in Adolescents

The relationship of circadian typology with personality has been largely studied in adults, but there are few studies exploring such relationship in adolescents. Adolescence has been associated with a greater tendency to eveningness preference, sleeping problems, poorer academic achievement, earlier substance use, or risky behaviors, and it is suggested that this association might be mediated by personality factors. Given the relevance of identifying the behavioral outcomes of young evening types to detect and prevent health problems, the present study aimed to explore, for the first time, the relationship between sensation seeking and circadian typology in an adolescent sample of 688 students (51.45% boys) from 12 to 16 yrs old. They answered the Spanish versions of the Morningness-Eveningness Scale for Children (MESC) and the Junior Sensation Seeking Scale (J-SSS), which includes four subscales measuring Thrill and Adventure Seeking, Experience Seeking, Disinhibition, and Boredom Susceptibility. Analyses showed that boys obtained significantly higher scores than girls on J-SSS total score and all subscales except Boredom Susceptibility, whereas evening-type adolescents of both sexes scored significantly higher than neither types and than morning types on J-SSS total score. These results indicate that evening-type adolescents show a greater desire for varied, new, complex, and intense sensations, and they are ready for experiencing more risks than morning types. The implications of this study suggest the need of being aware of individual differences in the SS trait in evening-type adolescents, as well as taking into account the wide variety of behaviors associated with it, either prosocial or antisocial, to design better preventive health and academic programs. (Author correspondence: anna.muro@uab.cat)     

Sleep and Academic Performance in Undergraduates: A Multi-measure,Multi-predictor Approach

The present study examined the associations of sleep patterns with multiple measures of academic achievement of undergraduate university students and tested whether sleep variables emerged as significant predictors of subsequent academic performance when other potential predictors, such as class attendance, time devoted to study, and substance use are considered. A sample of 1654 (55% female) full-time undergraduates 17 to 25 yrs of age responded to a self-response questionnaire on sleep, academics, lifestyle, and well-being that was administered at the middle of the semester. In addition to self-reported measures of academic performance, a final grade for each student was collected at the end of the semester. Univariate analyses found that sleep phase, morningness/eveningness preference, sleep deprivation, sleep quality, and sleep irregularity were significantly associated with at least two academic performance measures. Among 15 potential predictors, stepwise multiple regression analysis identified 5 significant predictors of end-of-semester marks: previous academic achievement, class attendance, sufficient sleep, night outings, and sleep quality (R²?=?0.14 and adjusted R²?=?0.14, F(5, 1234)?=?40.99, p?<?.0001). Associations between academic achievement and the remaining sleep variables as well as the academic, well-being, and lifestyle variables lost significance in stepwise regression. Together with class attendance, night outings, and previous academic achievement, self-reported sleep quality and self-reported frequency of sufficient sleep were among the main predictors of academic performance, adding an independent and significant contribution, regardless of academic variables and lifestyles of the students. (Author correspondence: ana.allen@ua.pt)     

METABOLIC RESPONSES ON THE EARLY SHIFT

Shiftwork has been associated with a higher propensity for the development of metabolic disorders and obesity. The aim of the study was to investigate concentrations of glucose, cortisol, and insulin among fixed night workers (n?=?9), fixed early morning workers (n?=?6), and day workers (n?=?7). Food intake was recorded for 7 days using a diary. Blood samples were collected every 4?h over the course of 24?h, yielding six samples. Total carbohydrate intake was lowest (p?<?.0005), whereas fat (p?=?.03) and protein (p?<?.0005) were highest on the early morning shifts. Early morning workers also had overall elevated cortisol levels relative to the other two groups. Cortisol levels appeared to be more influenced by time since waking prior to the shift than by time-of-day. Cortisol was highest for the early morning group than the day group 12?h after waking, and both the early morning and night groups had higher levels than the day group 16?h after waking (p?<?.05 in all cases). In contrast, the homesostatsis model assessment of insulin resistance (HOMA-IR) appeared to be more influenced by time-of-day than by time since waking prior to the shift. The early morning group had higher levels of HOMA-IR at 08:00?h than the other groups (p?<?.05). In conclusion, the early morning group had the highest overall concentrations of cortisol and tended to have higher levels of HOMA-IR, indicating that more attention should be given to these workers. Moreover, all three groups showed pronounced cortisol levels on awakening, suggesting that they may have adjusted to their awaking time. (Author: heloguarita@rgnutri.com.br)     

Associations Between Chronotypes,Psychopathology, and Personality Among Incoming College Students

Chronotye is associated with age, sex, personality, and parental monitoring during childhood. The evening type is associated with poor school performance, sleep problems, anxious/depressive symptoms, tobacco smoking, caffeine consumption, alcohol drinking, and suicidality in adolescents. The present study tested the relationships between chronotype and a wide range of psychopathology and personality traits among 2919 incoming undergraduate students. Each participant completed a self-administered questionnaire that included demographics, plus the Morningness-Eveningness (M-E) scale, Brief Symptom Rating Scale (BSRS), Tridimensional Personality Questionnaire, and Maudesley Personality Inventory. The t-score distribution of the M-E scale was used to form the morning (t-score >60, n?=?419), evening (t-score <40, n?=?371), and intermediate (40?≤?t-score?≤?60, n?=?2129) groups. Multivariable regression was employed for data analysis. For males, the evening type scored higher on all subscales of the BSRS than the morning type, except phobic anxiety. For females, the evening type had higher scores than the other two types on all subscales, except in obsession/compulsion and phobic anxiety, where the evening type only scored higher than the intermediate type. The evening type of both sexes also scored higher than the morning type in novelty seeking, harm avoidance, and neurotic personality characteristics, but lower than the morning type in extraversion and social desirability. In reward dependence, the evening type scored lowest for males, but there was no difference for females. The findings of the evening type being associated with possible psychopathology and certain types of personality have public health implications, that is, chronotype needs to be taken into account in the development of mental health prevention programs and assessment of and intervention for mental problems in young adults. (Author correspondence: gaushufe@ntu.edu.tw)     

EVENING PREFERENCE IS RELATED TO THE INCIDENCE OF DEPRESSIVE STATES INDEPENDENT OF SLEEP-WAKE CONDITIONS

Although evening preference has recently been identified as a risk factor for depression, it has not been substantiated whether evening preference is a direct risk factor for depressive states, or if it is associated secondarily through other factors, such as delayed sleep timing and shortened sleep duration. The objective of this study is to investigate associations in Japanese adult subjects between evening preference and incidence of depressive states, adjusting for various sleep parameters related to depressive states. The Morningness-Eveningness Questionnaire (MEQ), the Pittsburgh Sleep Quality Index (PSQI), and the Center for Epidemiologic Studies Depression Scale (CES-D) were administered to 1170 individuals (493 males/677 females; mean and range 38.5 and 20–59 yrs) to assess their diurnal preferences, sleeping states, and presence of depression symptoms. Subjects were classified into five chronotypes based on MEQ scores. Evening preference was associated with delayed sleep timing, shortened sleep duration, deteriorated subjective sleep quality, and worsened daytime sleepiness. Logistic regression analysis demonstrated that the extreme evening type (odds ratio [OR]?=?1.926, p?=?.018) was associated with increased incidence of depressive states and that the extreme morning type (OR?=?0.342, p?=?.038) was associated with the decreased incidence of depressive states, independent of sleep parameters, such as nocturnal awakening (OR?=?1.844, p?<?.001), subjective sleep quality (OR?=?2.471, p?<?.001), and daytime sleepiness (OR?=?1.895, p?=?.001). However, no significant associations were observed between the incidence of depressive states and sleep duration, sleep timing, and sleep debt (levels of insufficient sleep). Although the findings of this study do not demonstrate a causative relationship between evening preference and depression, they do suggest the presence of functional associations between mood adjustment and biological clock systems that regulate diurnal preference. They also suggest that evening preference might increase susceptibility to the induction of mood disorders. (Author correspondence: mishima@ncnp.go.jp)     

Relationship of Chronotype to Sleep,Light Exposure,and Work-Related Fatigue in Student Workers

Students who work during the school year face the potential of sleep deprivation and its effects, since they have to juggle between school and work responsibilities along with social life. This may leave them with less time left for sleep than their nonworking counterparts. Chronotype is a factor that may exert an influence on the sleep of student workers. Also, light and social zeitgebers may have an impact on the sleep-related problems of this population. This study aimed to document sleep, light exposure patterns, social rhythms, and work-related fatigue of student workers aged 19–21 yrs and explore possible associations with chronotype. A total of 88 student workers (mean?±?SD: 20.18?±?.44 yrs of age; 36 males/52 females) wore an actigraph (Actiwatch-L; Mini-Mitter/Respironics,Bend, OR) and filled out the Social Rhythm Metric for two consecutive weeks during the school year. Also, they completed the Morningness-Eveningness Questionnaire (MEQ), Epworth Sleepiness Scale (ESS), Pittsburgh Sleep Quality Index (PSQI), and Occupational Fatigue Exhaustion/Recovery Scale (OFER). Repeated and one-way analyses of variance (ANOVAs), Pearson's chi-square tests, and correlation coefficients were used for statistical comparisons. Subjects slept an average of 06:28?h/night. Actigraphic sleep parameters, such as sleep duration, sleep efficiency, wake after sleep onset, and sleep latency, did not differ between chronotypes. Results also show that evening types (n?=?17) presented lower subjective sleep quality than intermediate types (n?=?58) and morning types (n?=?13). Moreover, evening types reported higher levels of chronic work-related fatigue, exhibited less regular social rhythms, and were exposed to lower levels of light during their waking hours (between 2 and 11 h after wake time) as compared to intermediate types and morning types. In addition, exposure to light intensities between 100 and 500 lux was lower in evening types than in intermediate types and morning types. However, bright light exposure (≥1000 lux) did not differ between chronotypes. In conclusion, results suggest that student workers may constitute a high-risk population for sleep deprivation. Evening types seemed to cope less well with sleep deprivation, reporting poorer sleep quality and higher levels of work-related fatigue than intermediate types and morning types. The higher chronic work-related fatigue of evening types may be linked to their attenuated level of light exposure and weaker social zeitgebers. These results add credence to the hypothesis that eveningness entails a higher risk of health-impairing behaviors. (Author correspondence: luc.laberge@uqac.ca)     

TIME-OF-DAY EFFECTS ON COGNITION IN PREADOLESCENTS: A TRAILS STUDY

Cognitive performance fluctuates during the day due to diurnal variations in alertness level. This study examined: (1) whether cognitive performance in school-aged children is affected by time-of-day; (2) which functional domains are particularly vulnerable to time-of-day effects; and (3) whether the effects are more pronounced for cognitively more demanding tasks or task conditions. Children, aged 10–12 yrs, were randomly assigned to a test session starting either at 08:30 (n?=?802), 10:00 (n?=?713), or 13:00?h (n?=?652). Speed and accuracy of information processing were evaluated by tasks that assess input-related cognitive processes (e.g., stimulus encoding), central cognitive processes (e.g., working memory, sustained attention), and output-related processes (e.g., response organization) using the Amsterdam Neuropsychological Tasks program. Time-of-day effects in children were identified in specific neurocognitive domains, such as visuospatial processing and working memory, but only under cognitively more demanding task conditions. Sustained attention showed a speed-accuracy tradeoff with increased slowness and lapses in the early morning, but with better feedback responsiveness and perceptual sensitivity than in the early afternoon. Furthermore, there was a significant interaction of time-on-task with time-of-day for tempo, with the afternoon group increasing in tempo with time-on-task, and the early-morning group first showing a slowing of tempo with time-on-task, followed at the end of the task by a speed increase towards the initial levels. To conclude, the authors found time-of-day effects in preadolescents, which were confined to cognitively more demanding tasks tapping input-related and central cognitive processes. (Author correspondence: kbheijden@fsw.leidenuniv.nl)     

Adapting Test Timing to the Sleep-Wake Schedule: Effects on Diurnal Neurobehavioral Performance Changes in Young Evening and Older Morning Chronotypes

The synchrony effect refers to the beneficial impact of temporal matching between the timing of cognitive task administration and preferred time-of-day for diurnal activity. Aging is often associated with an advance in sleep-wake timing and concomitant optimal performance levels in the morning. In contrast, young adults often perform better in the evening hours. So far, the synchrony effect has been tested at fixed clock times, neglecting the individual's sleep-wake schedule and thus introducing confounds, such as differences in accumulated sleep pressure or circadian phase, which may exacerbate synchrony effects. To probe this hypothesis, the authors tested older morning and young evening chronotypes with a psychomotor vigilance and a Stroop paradigm once at fixed morning and evening hours and once adapting testing time to their preferred sleep-wake schedule in a within-subject design. The authors observe a persistence of synchrony effects for overall median reaction times during a psychomotor vigilance task, even when testing time is adapted to the specific individual's sleep-wake schedule. However, data analysis also indicates that time-of-day modulations are weakened under those conditions for incongruent trials on Stroop performance and the slowest reaction times on the psychomotor vigilance task. The latter result suggests that the classically observed synchrony effect may be partially mediated by a series of parameters, such as differences in socio-professional timing constraints, the amount of accumulated sleep need, or circadian phase, all leading to differential arousal levels at testing. (Author correspondence: f.collette@ulg.ac.be)     

Associations of Chronotype and Sleep With Cardiovascular Diseases and Type 2 Diabetes

In this study, the authors analyzed whether chronotypes, sleep duration, and sleep sufficiency are associated with cardiovascular diseases and type 2 diabetes by using the National FINRISK Study 2007 data (N?=?6258), being a representative sample of the population aged 25 to 74 living in five areas of Finland. Health status assessments and laboratory measurements from the participants (N?=?4589) of the DILGOM substudy were used for the detailed analysis of chronotype. Evening types had a 2.5-fold odds ratio for type 2 diabetes (p < .01) as compared with morning types, the association being independent of sleep duration and sleep sufficiency. Evening types had a 1.3-fold odds ratio for arterial hypertension (p < .05 after controlling for sleep duration or sleep sufficiency), a faster resting heart rate and a lower systolic blood pressure (both p < .01), and lower levels of serum total cholesterol and low-density lipoprotein cholesterol (both p < .0001) than morning types. There were significant 1.2- to 1.4-fold odds ratios for arterial hypertension among those with long or short sleep durations or reduced sleep sufficiency. To conclude, the behavioral trait towards eveningness is suggested to predispose individuals to type 2 diabetes in particular, whereas compromised sleep is robustly associated with arterial hypertension. (Author correspondence: ilona.merikanto@helsinki.fi)     

Sleep,Sleepiness, Fatigue,and Performance of 12-Hour-Shift Nurses

Nurses working 12-h shifts complain of fatigue and insufficient/poor-quality sleep. Objectively measured sleep times have not been often reported. This study describes sleep, sleepiness, fatigue, and neurobehavioral performance over three consecutive 12-h (day and night) shifts for hospital registered nurses. Sleep (actigraphy), sleepiness (Karolinska Sleepiness Scale [KSS]), and vigilance (Performance Vigilance Task [PVT]), were measured serially in 80 registered nurses (RNs). Occupational fatigue (Occupational Fatigue Exhaustion Recovery Scale [OFER]) was assessed at baseline. Sleep was short (mean 5.5?h) between shifts, with little difference between day shift (5.7?h) and night shift (5.4?h). Sleepiness scores were low overall (3 on a 1–9 scale, with higher score indicating greater sleepiness), with 45% of nurses having high level of sleepiness (score ?>?7) on at least one shift. Nurses were progressively sleepier each shift, and night nurses were sleepier toward the end of the shift compared to the beginning. There was extensive caffeine use, presumably to preserve or improve alertness. Fatigue was high in one-third of nurses, with intershift fatigue (not feeling recovered from previous shift at the start of the next shift) being most prominent. There were no statistically significant differences in mean reaction time between day/night shift, consecutive work shift, and time into shift. Lapsing was traitlike, with rare (39% of sample), moderate (53%), and frequent (8%) lapsers. Nurses accrue a considerable sleep debt while working successive 12-h shifts with accompanying fatigue and sleepiness. Certain nurses appear more vulnerable to sleep loss than others, as measured by attention lapses. (Author correspondence: jgeiger@son.umaryland.edu)     

INTERINDIVIDUAL DIFFERENCES IN NEUROBEHAVIORAL PERFORMANCE IN RESPONSE TO INCREASING HOMEOSTATIC SLEEP PRESSURE

Neurobehavioral function deteriorates with increasing homeostatic sleep pressure during wakefulness. It has been claimed that some individuals exhibit a quicker rate of such deterioration than others, thus being more vulnerable than others to the detrimental impact of increasing homeostatic sleep pressure. Evidence supporting the claim, however, has been limited by methodological issues. To overcome these limitations, the current study used a 12-calendar-day, 28-h forced desynchrony (FD) protocol (sleep:wake period?=?1:2) to study individual differences in the rate of change in neurobehavioral performance with increasing homeostatic sleep pressure. Neurobehavioral performance was assessed with a psychomotor vigilance task and a serial addition subtraction task. A significant performance decline on both tasks was revealed within as short as 17?h of wakefulness. The rates of decline of individual performance trajectories were, however, not different from the group average rate. This suggests that individuals are not differentially vulnerable to the detrimental impact of increasing homeostatic sleep pressure. (Author correspondence: xuan.zhou@unisa.edu.au)     

Adipokine Levels Are Altered by Shiftwork: A Preliminary Study

Shiftwork is often associated with metabolic diseases, and in the past few years, several cytokines have been postulated to contribute to various diseases, including insulin resistance. The aim of this study was to compare the concentrations of adiponectin, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) in samples of young adult men exposed to a fixed (i) night shift (n?=?9), working from 22:00 to 06:00?h; (ii) early morning shift (n?=?6), working from 06:00 to 14:00?h; and (iii) day shift (n?=?7), working from 08:00 to 17:00?h. The fixed night-shift and early-morning-shift samples were considered collectively as a shiftworker group given their work times. Blood samples were collected during the regular working day at 4-h intervals over the course of 24?h, thus totaling six samples. Morphological and physical activity parameters did not differ between the three groups. Total energy intake was lowest on the early morning shifts (p?<?.03). Both shiftworker groups ingested a significantly higher percentage of fat (p?<?.003) and a lower percentage of carbohydrate (p?<?.0005) than the day group. The early morning group had a lower mean 24-h level of adiponectin than the other two groups (p?=?.016), and both the early morning and night groups exhibited higher mean 24-h levels of TNF-α than the day group (p?=?.0001). The 24-h mean levels of IL-6 did not differ significantly between the groups (p?=?.147). None of the groups exhibited a significant circadian effect on adiponectin (p?=?.829), TNF-α (p?=?.779), or IL-6 (p?=?.979) levels. These results indicate that individuals who are enrolled in shiftwork are susceptible to alterations in the secretion of cytokines that are involved in insulin resistance and cardiovascular disease, both of which are known to affect this population. (Author correspondence: tmello@demello.net.br)     

Eveningness,Sleep Patterns,Daytime Functioning,and Quality of Life in Israeli Adolescents

The purpose of the study was to assess the relationships between eveningness, sleep patterns, measures of daytime functioning, i.e., sleepiness, sleep problem behaviors, and depressed mood, and quality of life (QOL) in young Israeli adolescents. A cross-sectional survey was performed in urban and rural middle schools in Northern Israel. Participants were 470 eighth and ninth grade middle school students (14?±?0.8 yrs of age) in the normative school system. Students completed the modified School Sleep Habits Survey (SSHS) and Pediatric Quality of Life Inventory Short Form, assessing six subscales of physical, emotional, social, school performance, and psychosocial functioning, plus an addition generated total score. During weekdays and weekends, evening types went to bed later, their sleep latency was longer, their wake-up time was later, and their sleep duration was shorter than intermediate and morning types. Evening types exhibited more sleep problem behaviors, sleepiness, depressed mood, and lower QOL compared to intermediate and morning types. Based on the regression model, sleepiness, sleep-problem behaviors, and depressed mood were the variables most strongly associated with QOL, followed by morning-evening preference, weekday sleep duration, and weekend sleep latency. This study is the first to assess QOL in normative, healthy adolescents and to demonstrate strong associations between morning-evening preference and QOL. These findings enhance the need to identify young individuals with an evening preference, and to be aware of the characteristics and manifestations of the evening chronotype on daytime and nighttime behaviors in adolescence. (Author correspondence: Orna@yvc.ac.il)     

A Honey Bee (Apis mellifera) Light Phase Response Curve

The authors report a phase response curve (PRC) for individual honey bees (Apis mellifera) to single 1-h light pulses (1000 lux) using an Aschoff Type 1 protocol (n?=?134). The bee PRC is a weak (Type 1) PRC with a maximum advance of 1.5?h between circadian time (CT) 18 and 3 and a maximum delay of 1.5?h between CT 12 and 18. This is the first published honey bee light PRC and provides an important resource for chronobiologists and honey bee researchers. It may also have practical applications for what is an economically important species frequently transported across different time zones. (Author correspondence: G.warman@auckland.ac.nz)