Morning Larks and Night Owls: The Impact of Chronotype

Post by Anastasia Sares

The takeaway

Chronotype, or day/night preference, is a genetically influenced trait that affects how active and alert we are at various points in the day. In the past few years, studies have linked chronotype to both mental and physical health, and people can suffer adverse effects when their daily schedule doesn’t align with their chronotype—a phenomenon called “social jet lag.”

How do we measure chronotype?

The simplest way to measure a person’s chronotype is by asking about their sleeping habits. It’s important to do this for workdays and for free days, as someone might change their habits between the two, and may try to make up for missed sleep on their free days by oversleeping. There are more objective ways to measure chronotype, but they take longer. Actimetry measures the amount of movement a person makes throughout the day by some kind of wearable device. Another popular measure is dim light melatonin onset, or DLMO, which measures how fast people produce the sleep-related hormone melatonin in response to dim light. All of these measures agree with each other pretty well, even an ultra-short version recently developed for use in clinics or as a part of other studies that don’t have much extra time.

Chronotype also varies hugely over the lifespan, with adolescents having very late chronotypes and older adults having earlier chronotypes. People in urban environments have more varied later chronotypes than those in rural environments, and even people’s location within a time zone (eastern vs. western edge) can affect their chronotype due to small differences in sunlight hours.

How is chronotype related to health outcomes?

Late chronotypes (night owls) are prone to more adverse health outcomes like hypertension and depression. However, it is not clear that being a night owl causes these effects. The less our daily schedule is synchronized with our natural sleeping rhythm, the more stress we experience, and this stress is what can lead to health problems. This is called “social jet lag,” and it is more likely to affect night-owls because societal structures tend to follow earlier schedules (the writer of this article, being a moderately late chronotype, still remembers getting up at 6:15 am during high school with much chagrin). Social jet lag is at its most extreme in shift-workers, like hospital staff who have work during the night.

Chronotype isn’t just a matter of psychology; every cell in the body has a circadian rhythm and is affected by these day-night cycles. Under social jet lag, the body’s cellular clocks adjust at different rates and cannot keep up with the switch between workdays and free days. It is these unsynchronized cellular clocks that may be responsible for the health risks of social jet lag. Worldwide, workers’ sleep habits when working from home during the COVID-19 pandemic shifted later, indicating that society as a whole had been under social jet lag.

How can we lessen the impact of social jet lag?

Chronotype can be manipulated to some degree. Being outside during the day can help to naturally regulate your sleep cycle. On the other hand, exposure to light before bed can disturb natural sleep-wake cycles, and so it is helpful to limit your evening screen time if you want to shift your schedule earlier (put away your phone!). A regular sleep schedule will also lower your risk for adverse health effects, especially if your work hours are very early or very late compared to your natural rhythm. However, don’t sacrifice your free-day sleep in order to keep a normal wake-up time. Rather, try to go to sleep at the same time each night.

On a societal level, we can take chronotype into account in school start times and in assigning shifts to workers, something that is already starting to be done. Some researchers are also calling for governments to abolish daylight savings time, which can cause a host of sleep-related problems.

What's the impact?

In our industrialized society, many people live predominantly indoors and are more detached from natural day-night cycles, making their chronotypes later and more varied. It is important to provide daily structures that accommodate differences in chronotype—this will have a significant impact on human health and well-being, as well as increasing work productivity and quality.

References +

1. Roenneberg, T., Pilz, L. K., Zerbini, G., & Winnebeck, E. C. (2019). Chronotype and social jetlag: A (self-) critical review. Biology, 8(3), 1–19. https://doi.org/10.3390/biology8030054
2. Shahid, A., Wilkinson, K., Marcu, S., & Shapiro, C. M. (2011). Munich Chronotype Questionnaire (MCTQ). STOP, THAT and One Hundred Other Sleep Scales, 245–247. https://doi.org/10.1007/978-1-4419-9893-4_58
3. Ghotbi, N., Pilz, L. K., Winnebeck, E. C., Vetter, C., Zerbini, G., Lenssen, D., … Roenneberg, T. (2020). The µMCTQ: An Ultra-Short Version of the Munich ChronoType Questionnaire. Journal of Biological Rhythms, 35(1), 98–110. https://doi.org/10.1177/0748730419886986
4. Kalmbach, D. A., Schneider, L. D., Cheung, J., Bertrand, S. J., Kariharan, T., Pack, A. I., & Gehrman, P. R. (2017). Genetic Basis of Chronotype in Humans: Insights From Three Landmark GWAS. Sleep, 40(2). https://doi.org/10.1093/sleep/zsw048
5. Wittmann, M., Dinich, J., Merrow, M., & Roenneberg, T. (2006). Social jetlag: Misalignment of biological and social time. Chronobiology International, 23(1–2), 497–509. https://doi.org/10.1080/07420520500545979
6. Hulsegge, G., Loef, B., van Kerkhof, L. W., Roenneberg, T., van der Beek, A. J., & Proper, K. I. (2019). Shift work, sleep disturbances and social jetlag in healthcare workers. Journal of Sleep Research, 28(4). https://doi.org/10.1111/jsr.12802
7. Korman, M., Tkachev, V., Reis, C., Komada, Y., Kitamura, S., Gubin, D., … Roenneberg, T. (2020). COVID-19-mandated social restrictions unveil the impact of social time pressure on sleep and body clock. Scientific Reports, 10(1), 1–10. https://doi.org/10.1038/s41598-020-79299-7
8. Roenneberg, T., Wirz-Justice, A., Skene, D. J., Ancoli-Israel, S., Wright, K. P., Dijk, D. J., … Klerman, E. B. (2019). Why Should We Abolish Daylight Saving Time? Journal of Biological Rhythms, 34(3), 227–230. https://doi.org/10.1177/0748730419854197

Lapses in Attention and Mind-Wandering are Related but Distinct Constructs

Post by Shireen Parimoo

The takeaway

Lapses in attention are more common in people who are prone to boredom, have poor attentional control, and a tendency to let their mind wander. Mind-wandering, on the other hand, is more strongly related to low motivation and alertness, as well as personality traits like conscientiousness and neuroticism.

What's the science?

We have all experienced days at work where we find it challenging to stay focused on the simplest of tasks. Lapses of attention can occur when we are disengaged from a task or when we let our mind wander, often negatively impacting our performance. The degree to which different causes of attentional lapses are related to each other, as well as to other cognitive abilities and personality traits is unclear. This week in Journal of Experimental Psychology: General, Unsworth and colleagues used latent variable analysis techniques to investigate the underlying causes of lapses in attention and whether individual differences might make some people more prone to experiencing attentional lapses than others.

How did they do it?

Participants were 358 young adults who completed a battery of cognitive tasks that assessed their working memory capacity (e.g., reading span), attentional control abilities (e.g., anti-saccade task), and lapses in attention (e.g., sustained attention to response task – SART). Participants also rated the degree to which they experienced task-unrelated mind-wandering by responding to infrequently presented thought probes during some of the tasks, as well as their level of motivation and alertness. Lastly, they filled out a series of self-report questionnaires assessing aspects of their personality (Big Five Inventory), proneness to boredom, daily cognitive failures including lapses in attention and memory, and sleep habits.

The authors first performed confirmatory factor analyses in which all the measures from the lapses of attention tasks were hypothesized to load onto a single latent factor (i.e., the construct of lapses in attention). In subsequent analyses, they tested whether the lapses of attention measures loaded onto the same factor as mind-wandering thoughts and attentional control or whether those were separable constructs. They then tested how all the cognitive factors were related to each other and to the questionnaire measures. Finally, the authors used structural equation modeling to determine which of the self-reported measures and cognitive factors uniquely contributed to (i) in-lab lapses in attention, (ii) daily cognitive failures, and (ii) task-unrelated mind-wandering, after accounting for the shared contribution of the remaining variables.

What did they find?

Behavioral measures of in-lab attentional lapses loaded onto a single latent factor, which means that those measures do arise from lapses in attention. Importantly, the factor of lapses in attention was distinct from both mind-wandering and attentional control, despite being correlated with them. Reduced attentional control and greater mind-wandering contributed to increased lapses in attention. Moreover, those who were more prone to boredom and lapses in attention in their daily lives were also more likely to experience greater lapses in attention on the cognitive tasks in the lab. In contrast, none of the cognitive factors predicted daily cognitive failures, only boredom proneness, conscientiousness, and neuroticism. These findings demonstrate that although in-lab lapses in attention are associated with boredom proneness, cognitive abilities, and everyday cognitive failures, everyday cognitive failures are primarily driven by personality traits.

Mind-wandering was not only distinct from lapses in attention but also showed a different pattern of correlations with other variables. For example, mind-wandering was associated with greater neuroticism and lower conscientiousness, whereas these personality traits were not related to lapses in attention. Compared to lapses in attention, mind-wandering was weakly related to attentional control and working memory but more strongly correlated with motivation and alertness. Lastly, greater lapses in attention, greater attentional control, and low alertness predicted greater mind-wandering. Thus, cognitive variables and personality traits differentially contribute to every day and in-lab lapses in attention and mind-wandering.

What's the impact?

This study found that lapses in attention and mind-wandering are related but separate constructs that arise from a distinct combination of cognitive abilities and personality traits. These findings provide greater insight into the different reasons why people have difficulty focusing on tasks and pave the way for developing effective interventions for improving task focus and performance.

Access the original scientific publication here.

P.S. This post is a part of our new BrainPost Behavior series. For more posts like this check out BrainPost Behavior.

What Impact Do Video Games Have On the Brain?

Post by Lani Cupo

What are the challenges of gaming research?

Entertainment video games represent an industry that has increased its influence during the COVID-19 pandemic. As people of all demographics and ages were locked down in their homes, gaming became an outlet, not only for personal entertainment but also to spend time with others.

The term “video games” comprises a vast category, including social simulation games like Animal Crossing, first-person shooters like Call of Duty, and multiplayer online battle arena games like League of Legends. Furthermore, they can be accessed through diverse means, such as computers, consoles (like the PlayStation or Xbox), or cell phones. While the increasing number of gamers worldwide only increases the interest in research assessing the impact of gaming on the brain and behavior, any discussion of the consequences and benefits of “gaming” should include a nuanced appreciation of the stark differences between different games and styles.

Gaming research is further complicated by confounding factors that frequently accompany gaming habits, such as screen time, time spent sedentary, and sleep deprivation. Additionally, habitual gaming can be conflated with gaming or internet addiction, where the activity interferes with general daily functioning. Furthermore, there is potential selection bias in studies that sample long-term gamers, as players may self-select based on prerequisite abilities. Finally, the stigma around gaming in some populations, such as girls and young women, can alter the demographics of long-term gamers, skewing the generalizability of results.

What has been the focus of gaming research in the past?

In 2017, a meta-analysis revealed one-third of papers examining gaming with neuroimaging discussed gaming addiction, and 14% focused on gaming-related violence. Currently, most research focuses on so-called “action games” that largely comprise first-person shooters. While the results from these studies provide detailed information pertaining to potential benefits and consequences of gaming, they do not necessarily represent the majority of gaming experiences outside of the laboratory accurately. Additionally, many studies draw from expert opinions without relying on empirical evidence. To facilitate the interest in the impact of gaming on the brain and behavior, future studies should integrate the complex mosaic of factors in the experimental paradigms they are designing.

What benefits can gaming have on the brain and behaviour?

Depending on the style of game (the tasks demanded and focus of gameplay) developing proficiency in a game can improve a variety of skill sets, from cognitive and motor skills to teamwork and social coordination. Enhancements to perception and certain forms of attention are among the forms of improvement documented following sessions of gaming in laboratories. The action games studied in labs tend to afford benefits to forms of attention and perception that allow gamers to quickly scan the screen for small visual differences (potentially signaling enemies) and quickly orient attention.

Gaming can also improve social cognition. Despite predominant stereotypes of lone gamers, over 70% play with a friend, either cooperatively or competitively. Many games award effective cooperation, support, and helping behavior. Evidence suggests children who engaged with prosocial gaming were more likely to demonstrate helping behavior than before playing. Even playing violent games cooperatively has been shown to encourage prosocial behaviors.

Finally, games can be used in an educational setting to teach certain concepts or behaviors. For example, a popular game called Re-Mission was developed to help pediatric cancer patients understand the importance of continuing their treatments. Interestingly, video games have recently been designed to mimic cognitive remediation therapies employed in populations with chronic Schizophrenia in order to help combat cognitive deficits observed in the disorder. Evidence from magnetic resonance imaging (MRI) studies suggests commercial video games induce similar alterations in brain volume and plasticity as the cognitive remediation therapy training exercises (focused on improving attention, working memory, executive functioning, and social cognition), involving the temporal and frontal areas and the hippocampus.

What detrimental effects can gaming have on the brain and behaviour?

Much of the interest in the impact of video games stems from the fear that playing violent games may make children violent or aggressive. Despite research that suggests playing large amounts of violent games may increase aggressive thoughts, the size of the effect is questionable. Alone, video games are unlikely to turn children violent. Nevertheless, an individual’s ability to regulate emotion and arousal may mediate the relationship between violent video games and aggression.

Over the past decades, video game research has become more nuanced, not only allowing for the possibility of positive effects but also directing focus to subtler consequences. While the ability of gamers to rapidly switch their attention between objects may be enhanced, they may suffer from detriments to sustained attention, which could negatively impact performance in school. Performance in school often depends on attending class or reading books, which require attention for longer periods. Adolescent students who game often demonstrate poorer academic outcomes than their counterparts.

While harmless habits should not be conflated with addictions, there is demonstrable evidence that gamers can form addictions to gaming. Gaming addictions are defined differently by country but must include interference with daily functioning. They can have serious consequences, including the sacrifice of sleep, work, education, in-person relationships, and high rates of loneliness. Introduced in the Diagnostic and Statistical Manual 5, gaming addiction prevalence is hard to document, but peaks in Southeast Asia at around 10% with higher rates among older than younger participants. 

What is the impact of gaming on the brain?

Playing video games likely engages and impacts reward processing in the brain. One study of 154 14-year-olds found that frequent gamers (>9 hours per week) demonstrated increased left striatal volume, as well as enhanced activity associated with experiencing loss in a laboratory gambling task (Cambridge Gambling Task). The activity and brain volume was negatively correlated with deliberation time in the same task, implying they were relevant for decision making and reward processing.

In a functional MRI study, violent scenes in first-person shooter games impacted activity in key limbic regions, including activation of the dorsal anterior cingulate and decreased activity in the rostral anterior cingulate and amygdala during virtual violence. Initially, when addiction is forming, the prefrontal cortex and ventral striatum play a role in the decision to initiate the addictive behavior (gaming, in this case). Over time, as a compulsion to gaming develops, the dorsal striatum is activated through dopaminergic connections, and the dopamine pathways can undergo permanent changes. 

What’s the bottom line?

While gaming may not have the overwhelmingly negative impact many politicians and parents once feared, the evidence is still mixed. Sustained, long-term attention is likely reduced in gamers, while the ability to quickly reorient attention may be enhanced. The social impact represents a double-edged sword, sometimes contributing to prosocial behavior and other times increasing loneliness. Nevertheless, to establish a more comprehensive understanding of the impact of video games, researchers must incorporate greater nuance into the personal demographics of their participants and the complexities of the games they are exposed to.

Click to See References +

Bavelier et al. Brains on Video Games. Nature Reviews. Neuroscience (2011). Access the original scientific publication here.

Granic et al. The Benefits of Playing Video Games. The American Psychologist. (2014). Access the original scientific publication here.

Kühn et al. The Neural Basis of Video Gaming. Translational Psychiatry. (2011). Access the original scientific publication here.

Kuss et al. Internet Gaming Addiction: Current Perspectives. Psychology Research and Behavior Management. (2013). Access the original scientific publication here.

Mathiak, Klaus, and René Weber. Toward Brain Correlates of Natural Behavior: fMRI during Violent Video Games. Human Brain Mapping. (2006). Access the original scientific publication here.

Palaus et al. Neural Basis of Video Gaming: A Systematic Review. Frontiers in Human Neuroscience. (2017). Access the original scientific publication here.

Suenderhauf et al. Counter Striking Psychosis: Commercial Video Games as Potential Treatment in Schizophrenia? A Systematic Review of Neuroimaging Studies. Neuroscience and Biobehavioral Reviews. (2016). Access the original scientific publication here.

Unsworth et al. The Effect of Playing Violent Video Games on Adolescents: Should Parents Be Quaking in Their Boots? Psychology, Crime & Law: PC & L (2007). Access the original scientific publication here.