Abstract: Recent research revealed an association between chronotype and psychological constructs of eating behaviour. Here, we used food logs in adolescents and assessed their chronotype. We found that later bed and rise times were associated with the tendency to drink caffeinated drinks and eat fast food and to consume less dairy products. No relationship existed between chronotype and sweets, vegetables and salad, and meat consumption. These results suggest a healthier lifestyle in morning oriented adolescents (or late chronotypes). Breakfast times differed between weekdays and weekend while lunch and dinner times were similar. Mean breakfast time at the weekend was later in late chronotypes which was a result of later rise times of late chronotypes. The study showed that morning oriented pupils exhibit a healthier and more regular lifestyle.
Abstract: BACKGROUND: Individuals differ in their biological rhythms and preferences for time of day. Here, we looked at the transition into daylight saving time (DST) in adolescents. As adolescents tend to be evening types, one may expect that they suffer from a transition into DST. METHODS: To assess these changes, we measured daytime sleepiness and morningness-eveningness preference (CSM score) in adolescents. RESULTS: Daytime sleepiness correlated with age and CSM score. Older pupils and evening types showed a higher sleepiness. Daytime sleepiness was higher after the transition until the third week after. Older pupils and pupils scoring higher on eveningness reported higher daytime sleepiness after the transition, suggesting that these pupils suffer most from the change. Using cut-off scores for larks and owls, we found that owls showed higher sleepiness than larks. CONCLUSION: As one consequence, class and school performance tests should not take place in the first week(s) after the transition into DST.
Abstract: Different factors have been proposed to influence morningness-eveningness, biological rhythms, and sleep-wake cycles, but few studies focused on the influence of social habits. Here, we focus on the influence of children and partners on the social habits of women at different stages of their lives and on synchronization within the family. One hundred and seventy-nine women participated in the study and were allocated into four groups: women without children, pregnant women without children, pregnant women with children, and non-pregnant mothers. Morningness was predicted by the presence of children, and earlier chronotype was predicted by the presence of children, pregnancy, and age. Average sleep duration was longest in pregnant women. The presence of children was responsible for a difference in rise times of approximately 1.5 h on the weekend. Subjective sleep-onset latencies were shortest in women with children. The synchrony between partners (husband/wife) was 0.46 in women without children, 0.79 in pregnant women, 0.40 in women with children, and 0.56 between mother and child. Partners' chronotypes were highly correlated, as were those of mother and child. This study suggests children have a strong influence on their mother's lifestyle and sleep-wake rhythm, far beyond the first months of life, and that children are a more important social factor than the male partner.
Abstract: The aim of this study was to explore associations between chronotype and the Three-Factor-Eating-Questionnaire. We found a positive association between morningness and dietary restraint and negative correlations between morningness and disinhibition and perceived hunger. Further, there was an association between morningness and flexible control. BMI tended to be negatively associated with morningness and correlated with disinhibition and with the sub-scale RC7. No association was found between BMI and cognitive restraint, hunger and flexible control. Also, no relationships existed between sleep length on weekdays or on weekends and BMI or eating.
Abstract: Only a few studies focus on comparisons to reveal differences in sleep and circadian preferences in adolescents. This study used the same instrument to compare adolescents in Eastern and Western Germany. In all, 674 pupils between 11 and 16 yrs participated. The questionnaire asked questions about wake times and bed times (on weekend and weekdays), and the Composite Scale of Morningness (CSM) was completed to assess diurnal preferences. Locality (East/West Germany) had no effect on rise and bed times during the week and on sleep length on the weekend. Western pupils rose later on weekends and went to bed later on weekends. While sleep length on weekdays was shorter in West Germany, weekend oversleep was longer and misalignment was higher. Diurnal preferences (CSM scores) suggested a higher eveningness in West Germany. As interaction effects were insignificant, changes throughout adolescence seem similar in East and West Germany. These data suggest that given similar school start times, Western German pupils are at higher risk because they are later chronotypes. The finding of earlier rise and bed times of the East German pupils is consistent with the hypothesis that sunlight acts as the entrainment for the biological clock of adolescents, as sunrise is earlier in Eastern Germany.
Abstract: Very few studies have focused on differences in chronotype around the globe. In this study, morningness-eveningness was measured using the Composite Scale of Morningness and the midpoint of sleep on free days (corrected for sleep debt, MSF(sc)) in adolescents of sixteen German schools abroad, dispersed all over the world, and for comparison pupils attending German schools. There was no influence of duration of residence in the respective locality, and sex differences were weak. Age correlated negatively with morningness. A significant influence of climate zone (temperate, subtropics, tropics) was found, with adolescents in the subtropics being the latest chronotypes, and an interaction of agexclimate zone was identified. Significant associations between chronotype and longitude and latitude were identified within the time zone of central Europe. Adolescents were found to be more morning oriented both toward the East and North. The results indicate that climate, longitude, and latitude contribute to chronotype.
Abstract: Humor research has focused on relationships between humor and various personality traits. As personality and morningness-eveningness, as well as personality and humor, are related based on genetics and neurobehavioral function, one might also expect a relationship between humor and chronotype. 197 students responded to the Composite Scale of Morningness as a measure of chronotype, the Sense of Humor Questionnaire and a 10-item version of the Big Five Inventory. Individuals scoring as evening types reported a greater sense of humor than morning individuals, with higher morningness scores. In a stepwise linear regression, Extraversion, Agreeableness, Openness, and Chronotype each accounted for a significant amount of variance in sense of Humor scores. That is, the relationship between scores on Sense of Humor and evening orientation was significant after controlling for personality dimensions. Eveningness was related to sense of Humor scores in women but not in men. Social but not cognitive humor was predicted by eveningness.
Abstract: Footedness in birds has been reported, e.g., in parrots and chickens, but the direction of footedness remained unclear. Is a bird left-footed because it uses its left foot for holding and handling food, or is it right-footed because it uses the right foot for stabilisation and balancing while perching? In 2004 and 2006 I examined footedness in wildfowl and waders while the birds were performing a single task: roosting on the ground on one foot. Avocet (Recurvirostra avosetta), northern shoveller (Anas clypeata), oystercatcher (Haematopus ostralegus), and Eurasian curlew (Numenius arquata) were right-footed. Another 21 species did not show any significant foot preferences. This study provides some evidence that asymmetries in preferential foot use in birds may be triggered by a preference during postural control.
Abstract: Birds frequently interrupt feeding to scan their surrounding environment. Usually an inverse correlation between scan rate and flock size exists. The 'many-eyes' hypothesis suggests that more eyes are able to detect a predator earlier. Due to the 'dilution-effect' animals in larger groups experience 'safety in numbers', while the 'scramble competition' hypothesis suggests that individuals reduce their vigilance in larger groups since they compete for a limited amount of scarce resources. Here, I induced competition in natural coot populations. Coots preferred feeding on grass and were occasionally fed by passers-by at the study sites. However, this resource was scarce and coots experienced additional food as a very limited resource. I sampled coots prior and after an experimental treatment with an additional food supply. Correlations between vigilance rate (number of scans during 1 min of foraging), nearest neighbor distance and flock size existed before the experimental treatment but afterwards the correlation between vigilance and nearest neighbor distance faded. I found a significantly lower vigilance rate and nearest neighbor distance after inducing competition. This study provided experimental evidence for the 'scramble competition' hypothesis namely that individuals in groups lowered their vigilance when faced with competition for a limited amount of food resources given similar flock sizes.
Abstract: Most research in avian brain lateralisation has been done using birds under laboratory conditions rather than natural settings. I studied eye preference during feeding in coot and geese when head position only allows use of one eye for vigilance. Birds regularly interrupt feeding to be vigilant. This behaviour is directed towards detecting predators. Recently, evidence was found that birds might perform some kind of "low-cost" vigilance even during feeding. Because coot and geese often turn their head to either side during feeding, laterality in head turning is expected to follow a consistent pattern in which the eye used for detecting predators should be less often directed towards the obstructive ground. Coot and geese were digitally videotaped and the number of pecks with either side oriented towards the ground at an angle of at least 45 degrees was counted. I found a strong bias in swan geese oriented their left eye towards the ground and thus using the right eye for vigilance during feeding. Coot showed a similar but less pronounced pattern, while in greylag geese no preference could be detected.
