Morning Larks Research Articles

Beyond larks and owls: Revisiting the circadian typology using the MESSi scale and a cluster-based approach.

Chronopsychological research typically applied the morningness-eveningness dimension, resulting in a distinction between morning, intermediate, and evening chronotypes. However, in recent years, new measures have been developed that transcend the traditional "morning larks" vs. "night owls" dichotomy and better capture the complexity of individual differences in circadian rhythmicity. One such measure that addresses the multidimensional character of the circadian rhythm is the Morningness-Eveningness-Stability Scale improved (MESSi) which comprises three dimensions: morning affect, eveningness, and distinctness. However, delineating specific chronotypes using the cut-off points, as was commonly done for other established scales, is not possible in the case of MESSi due to its multidimensionality. In the present paper, we provide a first attempt to introduce a cluster-based approach to deal with MESSi scores. For this purpose, we determined the number of clusters to be extracted using data from our previous study conducted in Poland (N = 1106). Next, we attempted to replicate this cluster solution in another Polish sample (N = 768) and a German sample (N = 637). Finally, we also intended to illustrate how individuals assigned to the established clusters differ in terms of sleep parameters and other differential variables such as positive and negative affect, personality traits, depressive and anxiety symptoms, self-regulation, and self-efficacy. After segmenting MESSi scores by cluster analysis in the three samples we found support for a four-cluster solution, including four circadian profiles which we propose to label "intermediate-finches", "hardy larks", "night owls", and "vulnerable larks". This is the first attempt to introduce a cluster-based, multi-dimensional approach to dealing with MESSi scores.

Are “night owls” or “morning larks” more likely to delay sleep due to problematic smartphone use? a cross-lagged study among undergraduates

Sleep is an important physiological process, but staying up late has become a worldwide problem, particularly among university students. Sleep procrastination has been found to associated with sleep biorhythms and problematic smartphone use (“PSU”) in previous studies. This two-wave study examines the longitudinal reciprocal relationship between PSU and sleep procrastination, together with the moderating role of sleep biorhythms. Participants comprised 1,423 Chinese university students. The results revealed that PSU and sleep procrastination are reciprocally related. Additionally, sleep biorhythms moderated this relationship, as PSU at T1 significantly predicted sleep procrastination at T2 for the morning larks group but not the night owls group. Accordingly, both PSU and sleep biorhythms should be considered when developing interventions for sleep procrastination.

The association between chronotype and wages at mid-age

Sleep has been shown to affect economic outcomes, including wages. The mechanisms by which sleep affects wages remain unclear. We examine the relationship between chronotype – morning larks, evening owls – and wages at mid-age. We propose a novel model relating chronotype to wages in consideration of human, social, and health capital constructs. Empirically, we explore the effects of chronotype mediated through life course choices, such as work experience, trust, and health behaviour. The data come from the 46-year-old follow-up study of the Northern Finland Birth Cohort (1966) and from registers of the Finnish Tax Administration. We find evening chronotype to have a significant indirect negative effect on wages, which occurs through accumulating less work experience and through poor health outcomes. The effect is largest for male workers, with a total indirect effect on average wages of − 4%. We also provide evidence that chronotype has a long-term association with wages between 29 and 50 years of age. We conclude that evening-type workers are less suited to typical working hours and accumulate less human, social and health capital which in turn negatively affects their wages. Our findings are of great socio-economic importance because evening chronotypes make up a significant part of the population.

Chronotype in college science students is associated with behavioral choices and can fluctuate across a semester

ABSTRACT Many students self-report that they are “night owls,” which can result from neurodevelopmental delays in the circadian timing system. However, whether an individual considers themselves to be an evening-type versus a morning-type (self-reported chronotype) may also be influenced by academic demands (e.g. class start times, course load) and behavioral habits (e.g. bedtime social media use, late caffeine consumption, daytime napping). If so, then chronotype should be malleable. We surveyed 858 undergraduate students enrolled in demanding science courses at up to three time points. The survey assessed morning/evening chronotype, global sleep quality, academics, and behavioral habits. Evening and morning-type students showed similar demographics, stress levels, and academic demands. At baseline measurements, relative to morning-types, evening-types showed significantly worse sleep quality and duration as well as 22% greater bedtime social media usage, 27% greater daytime napping duration, and 46% greater likelihood of consuming caffeine after 5pm. These behavioral habits partially mediated the effects of self-reported chronotype on sleep quality/duration, even after controlling for demographic factors. Interestingly, 54 students reported switching from being at least moderate evening-types at baseline to being at least moderate morning-types later in the semester and 56 students showed the reverse pattern (6.3% of students switched from “definitely” one chronotype to the other chronotype). Evening-to-morning “chrono-switchers” consumed less caffeine after 5pm and showed significantly better sleep quantity/quality at the later timepoint. Thus, some students may consider themselves to be night owls in part because they consume caffeine later, take more daytime naps, or use more social media at bedtime. Experimental work is needed to determine whether nudging night owls to behave like morning larks results in better sleep health or academic achievement.

Diurnal Preference Contributes to Maximal UVB Sensitivity by the Hour of the Day in Human Skin In Vivo

Diurnal Preference Contributes to Maximal UVB Sensitivity by the Hour of the Day in Human Skin In Vivo

To Challenge the Morning Lark and the Night Owl: Using Smartphone Sensing Data to Investigate Day–Night Behaviour Patterns

For decades, day–night patterns in behaviour have been investigated by asking people about their sleep–wake timing, their diurnal activity patterns, and their sleep duration. We demonstrate that the increasing digitalization of lifestyle offers new possibilities for research to investigate day–night patterns and related traits with the help of behavioural data. Using smartphone sensing, we collected in vivo data from 597 participants across several weeks and extracted behavioural day–night pattern indicators. Using this data, we explored three popular research topics. First, we focused on individual differences in day–night patterns by investigating whether ‘morning larks’ and ‘night owls’ manifest in smartphone–sensed behavioural indicators. Second, we examined whether personality traits are related to day–night patterns. Finally, exploring social jetlag, we investigated whether traits and work weekly day–night behaviours influence day–night patterns on weekends. Our findings highlight that behavioural data play an essential role in understanding daily routines and their relations to personality traits. We discuss how psychological research can integrate new behavioural approaches to study personality.

0197 Chronotype is Influenced by Behavioral Choices and Can Fluctuate Across the Semester in STEM Students

Abstract Introduction A delay in endogenous biological rhythms is assumed to cause undergraduate students to be “night owls,” but neurodevelopmental effects may only partially explain chronotype (circadian preference). Instead, perceived chronotype in students may result from poor sleep hygiene practices including bedtime social media use, afternoon caffeine consumption, and daytime napping. If so, then chronotype should be malleable in students to the extent that behavioral choices change. Methods We surveyed 1,120 undergraduate students who were enrolled in STEM courses across up to 3 time points during the semester. The survey assessed perceived chronotype (morning/evening type), global sleep quality, and daily habits that impact alertness and sleep hygiene (e.g., social media usage and timing, caffeine consumption and timing, and napping behavior). Results Relative to Morning Types, students who perceived themselves as being Evening Types showed 23.1% greater bedtime social media usage (t=3.14, p=.002), 35.1% greater daytime napping duration (t=4.44, p<.001), and a 44 minute later average time of caffeine consumption (even though total caffeine consumption was reduced; t=2.30, p=.022). Evening Types also reported lower subjective health (t=3.55, p<.001), with 14.2% of the association between chronotype and subjective health being mediated by bedtime social media use (direct effect: b=0.050, p=.002; indirect effect: b=0.009, p<.05). Ninety-one students reported switching from being Evening Types at baseline to Morning Types at a later survey; those who switched to Morning Types used less social media and consumed less caffeine after 5pm and they showed significant improvements across the semester in sleep duration, sleep quality, and exam scores (ps<.05). Conclusion Perceived chronotype is related to social media and caffeine consumption behaviors and is modifiable. Students who perceive themselves as night owls may find better health and academic success if they behave like morning larks. Support National Science Foundation (DRL 1920730)

Let Teens Sleep In

Last month, I wrote about the different ways that self-control strategies can help all of us, especially the teenagers in our lives, sleep better. I hope these tips have helped you make progress on your own New Year's resolutions. But self-control isn't the only way to fight temptation. Sometimes, the smartest solution is for other people to solve our problems for us. In particular, one policy change could radically increase the amount of time teenagers sleep: delay the start time of classes to an hour that more closely fits their biological clocks. A recent Rand report concluded that starting both middle and high school classes no earlier than 8:30 a.m. would translate into $8.6 billion in economic gains within two years of the change. How so? Adequate sleep can improve academic achievement, which correlates with higher income in adulthood. And more well-rested teenagers get into fewer car accidents. Like so many common sense policies, delaying start times for high school students has met with resistance. One issue is budget: for many districts, it's necessary to stagger bus schedules to save money. True, but why not flip-flop times so that elementary school students—who are natural morning larks—are picked up earlier, making it possible for middle and high school students—who are natural night owls—to go later? “Well, I don't love the idea of my 11-year-old waiting for the bus in the dark,” one mom told me. Her district had just announced precisely the sort of transportation schedule I'm describing.

Morning larks travel more than night owls? Chronotypical effect on travel frequency through novelty seeking

Chronotype is a characterization of people's propensity to sleep at a particular time, spanning a spectrum from the two extremes of “morning larks,” who go to sleep early and rise early, and “evening owls,” who go to sleep late and rise late. We study the relationship between chronotype and the tendency to seek novelty in travel preference. Surprisingly, in contrast to the case of domain-general novelty seeking, morning larks are more domain-specific in their novelty seeking than night owls in relation to travel. To test the significance of this finding, we explore the downstream behavioral consequences of the tendency to be novelty seeking. Travel frequency for leisure is found to increase with novelty seeking. In addition, chronotype has an indirect effect on travel frequency through its influence on novelty seeking—a mediation relationship moderated by gender, with the effect of chronotype on novelty seeking especially strong among young females.

Circadian rhythms and mood disorders: a guide for the perplexed.

Circadian rhythms and mood disorders: a guide for the perplexed.

The Impact of Early Bedtimes on Adolescent Caloric Intake Varies by Chronotype

PurposeAdolescent sleep restriction is common and can lead to overeating. Here, we test whether lengthening sleep via early bedtimes affects dietary intake differently for adolescents accustomed to a later sleep phase (“night owls”) versus an earlier sleep phase (“morning larks”). MethodsUsing a randomized cross-over design, 67 adolescents changed bedtimes to create five-night periods of sleep restriction (6.5 hours in bed) versus healthy sleep (10 hours in bed). Caloric intake was measured via validated interviews. Phase preference was based on participants' premanipulation sleep. ResultsActigraphy verified that the manipulation altered sleep regardless of phase preference. Phase preference moderated the effect of the manipulation on cumulative caloric intake (p = .01–.03). Night owls showed little effect, but morning larks reduced their evening intake during healthy sleep. ConclusionsAn “early to bed” approach confers little dietary benefit for night owls but may have a protective effect for adolescents who gravitate toward earlier bedtimes.

Adaptation of the Composite Scale of Morningness for Parent Report and Results from Kindergarten Children

Chronotype, or morningness-eveningness, refers to a person’s preference for a given time of day for intellectual and/or physical activities. It has many implications on health, well-being, performance, and daytime functioning. Because few data are available on prepubertal children, we assessed morningness-eveningness in kindergarten children using a parent-report scale, which was an adapted version of the Composite Scale of Morningness (CSM), and sleep-wake variables. A total of 199 parents of children from 15 kindergartens participated in the study. The CSM scores were relatively high, with a mean above 40 for all age groups, which clearly indicates that young children are early morning larks. Weekend wake-up times, rise times, bedtimes, and sleep-onset times were later than on weekdays. Sleep length did not differ in this respect, but time in bed was longer on weekends. Midpoint of sleep was earlier on weekdays. Wake times, rise times, bedtimes, and sleep-onset times were inversely correlated with the CSM score, suggesting that morning-oriented children woke up, got out of bed, went to bed, and fell asleep earlier than evening-oriented children. CSM scores correlated negatively with midpoint of sleep. Age correlated with CSM scores and midpoint of sleep.

Clock T3111C and Per2 C111G SNPs do not influence circadian rhythmicity in healthy Italian population

A possible relationship between human circadian rhythmicity and polymorphisms in clock genes have been documented. However, these data are controversial, and studies both corroborating and denying them have been reported. T3111C Clock polymorphism had been associated with the human evening preference, however, this association has not been confirmed. Moreover, C111G Per2 polymorphism has been associated with the "morning larks" chronotype in one study, not yet replicated. We have, therefore, performed this study to evaluate whether Per2 C111G and Clock T3111C polymorphisms might influence sleep circadian rhythmicity in a sample of 219 Italian volunteers. A possible interaction between these polymorphisms was also investigated. No differences in Per2 C111G and Clock T3111C allele and genotype frequencies were found, and none of the combined Clock T3111C-Per2 C11G genotypes resulted more frequent in one group compared to the others. Present results do not support a role of these polymorphisms in the circadian phenotypes.

Evolutionary psychology and intelligence research.

This article seeks to unify two subfields of psychology that have hitherto stood separately: evolutionary psychology and intelligence research/differential psychology. I suggest that general intelligence may simultaneously be an evolved adaptation and an individual-difference variable. Tooby and Cosmides's (1990a) notion of random quantitative variation on a monomorphic design allows us to incorporate heritable individual differences in evolved adaptations. The Savanna-IQ Interaction Hypothesis, which is one consequence of the integration of evolutionary psychology and intelligence research, can potentially explain why less intelligent individuals enjoy TV more, why liberals are more intelligent than conservatives, and why night owls are more intelligent than morning larks, among many other findings. The general approach proposed here will allow us to integrate evolutionary psychology with any other aspect of differential psychology.

Night owls and morning larks

Researchers at the Howard Hughes Medical Institute (Salt Lake City,UT, USA) have discovered the first gene to be involved in human circadian rhythms – the biology that determines our sleep patterns. Whilst investigating a recently-identified familial sleeping disorder, in which sufferers typically fall asleep at 7 pm and wake up at 2 am, the authors revealed a mutation in a gene called hPer2, which disrupts phosphorylation of the hPer2 protein. Uncovering this mutation, and indeed the syndrome proved to be unusually hard: ‘One problem with distinguishing a familial circadian disorder is that there are wide variations in sleep patterns, with some of us being morning larks, some of us night owls, and many of us in between’, commented Louis J. Ptatek, one of the researchers. This work might help the design of drugs that prevent international travellers and night-shift workers to avoid potentially hazardous fatigue. AR

An hPer2 phosphorylation site mutation in familial advanced sleep phase syndrome.

Familial advanced sleep phase syndrome (FASPS) is an autosomal dominant circadian rhythm variant; affected individuals are "morning larks" with a 4-hour advance of the sleep, temperature, and melatonin rhythms. Here we report localization of the FASPS gene near the telomere of chromosome 2q. A strong candidate gene (hPer2), a human homolog of the period gene in Drosophila, maps to the same locus. Affected individuals have a serine to glycine mutation within the casein kinase Iepsilon (CKIepsilon) binding region of hPER2, which causes hypophosphorylation by CKIepsilon in vitro. Thus, a variant in human sleep behavior can be attributed to a missense mutation in a clock component, hPER2, which alters the circadian period.

Shiftwork

1. Humans are designed to sleep at night and work during the day; thus, shiftwork is inherently non-physiological. The species has not yet evolved to the point of being able to adjust to a 24 hour day, despite society's demands. 2. Certain individuals may be better able to cope with the requirements of shiftwork than others. Women may be less able than men to do so because of the demands of home and family life and physiological differences. 3. Shifts can be designed to be more or less difficult for certain individuals. "Night owl" individuals might do best with evening shifts, "morning larks" with shifts starting in the early morning.