Anne-Marie Neumann, Institute of Neurobiology, Center of Brain, Behavior & Metabolism, University of Lübeck, Germany

https://doi.org/10.36866/pn.113.20

Circadian systems play a crucial role in the physiology and health of living beings, adapting processes to the 24-hour light-dark cycle of the Earth. Although around 50% of mammalian genes present circadian oscillations, the concepts of circadian rhythms are rarely established in research groups other than those specifically focused on clocks and rhythms (Zhang et al., 2014). As a PhD student specialising in neuroscience and working on behavioural and metabolic rhythms after weight-loss surgery, I firmly believe non-consideration of biological rhythms is a major shortcoming of many scientific studies. This may be due to persisting gaps in chronobiological training at universities and a general lack of its awareness in parts of the biomedical community.

As for most people, I grew up with chronobiological advice like “Do not eat too late!” and “Disrupted sleep is unhealthy!”, and encountered the phenomena of jet lag and inner clocks. Despite this, contact with rhythms and clocks in a scientific way required travelling across the globe. I did not come across the term “circadian clock” until I attended the Neuroscience 2014 conference in Yokohama and listened to a lecture by Paolo Sassone-Corsi – a prominent researcher in the circadian clocks field with a specialty in epigenetics and metabolism. In combination with a growing interest in behavioural biology his talk struck a chord.

Unfortunately, maybe due to a lack of research groups investigating molecular mechanisms underlying psychiatry and behavioural rhythms in northern Europe, it took a while after graduation to find a PhD position covering my newly discovered scientific passions. And only now do I fully grasp the importance of rhythms and proper timing of experiments in science. In my previous studies, I never considered whether testing at another time point may change experimental outcomes, but with my broadened awareness and knowledge today, I will keep a chronobiological perspective no matter the field I will work in in the future. I think, if you are once a chronobiologist, you will always be a chronobiologist. Even some small exposure to the field for young scientists and medical trainees could pay dividends in terms of integrating chronobiology into domains where it has not been previously considered.

Despite the importance of such an integral system, without professors or readers investigating the topic themselves, chronobiology appears to be neglected. When taking a brief look into textbooks this comes as no surprise: “circadian rhythms” are granted 4 pages out of 979, 10 out of 980, and 9 out of 469 in standard physiology (2017), neuroscience (2016), and endocrinology (2014) textbooks, respectively (Schmidt et al., 2017; Bear et al., 2016; Kleine & Rossmanith, 2014). The topic still needs to thoroughly arrive in textbooks; all junior (and senior) academics should, at least, stumble upon it.

The biology of circadian clocks was not taught during my medical biotechnologist undergraduate training despite mandatory year-long lecture series on general physiology, neuroscience, and their applications in medicine. To the best of my knowledge, medical training similarly lacked teaching of chronobiology. Since then, changes in academic personnel has helped establish the field within the psychiatry department at my Alma Mater and will inevitably promote teaching chronobiology therein.

Currently in Lübeck, circadian clocks are taught to different medical science programmes within a wide-ranging bachelor’s physiology series and within a master’s neuroscience course. The physiology course mostly discusses the molecular aspects of circadian timekeeping, while the neuroscience course covers more ground, elucidating the interaction of clocks with various brain functions – from memory formation to appetite regulation. Additionally, a laboratory practical week is offered for master’s students. A single professor focusing on chronophysiology on site was teaching all of these courses. The topic clearly inspires: every year students have joined the group after that week for their Master’s projects and even PhDs. Moreover, within my international research training group only a handful of PhD students heard of circadian clocks during their respective Master’s programmes. Today, they are all acknowledging its relevance for science; most have started to consider including certain aspects in their work.

Circadian clocks should be of major interest for everyone studying processes with underlying biological rhythmicity: physiologists, neuroscientists, biochemists, nutritionists, immunologists, endocrinologists, pharmacologists and so on. To understand the complexity of chronobiology, a few lecture hours may not be enough, but should definitely be the minimum. Additionally, specialised courses and summer schools accessible for students not already working in the field, as well as workshops at young researcher meetings may be a step in the right direction.

Luckily, circadian clock research gained a boost of attention due to the awarding of the 2017 Nobel Prize in Physiology or Medicine to Jeffrey C Hall, Michael Rosbash and Michael W Young for discovering the molecular mechanisms controlling the circadian rhythm. In addition to the recurring discussions in many European countries about whether daylight-saving time is still needed, chronobiology became more attractive for students and postgrads alike.

This trend should be used to further anchor circadian biology within all kinds of medical and natural science courses. Young physiologists need to be encouraged to include circadian aspects in their experimental designs. Hopefully, this will lead to more awareness among scientists and, consequently, better education and research. Moreover, patients could greatly benefit from improving and implementing knowledge of best drug dosage timing, impact of chronotypes on treatment outcomes, healthy hospital lightning conditions and synchronisation of scheduled surgeries with biological rhythms. Overall, chronobiology should be seen as fundamental for physiologists and physicians alike.

References

Bear MF, Connors BW, Paradiso MA (2016). Neurowissenschaften: ein grundlegendes Lehrbuch für Biologie, Medizin und Psychologie. 3rd edition. Andreas K. Engel (ed.). Berlin Heidelberg, Springer Spektrum.

Kleine B, Rossmanith WG (2014). Hormone und Hormonsystem: Lehrbuch der Endokrinologie. 3rd edition. Berlin, Springer Spektrum.

Schmidt RF, Lang F, Heckmann M (2017). Physiologie des Menschen: mit Pathophysiologie: mit Online-Repetitorium. Limited Reprint 31st edition. Berlin: Springer.

Zhang R, Lahens NF, Ballance HI et al. (2014). A circadian gene expression atlas in mammals: Implications for biology and medicine. Proceedings of the National Academy of Sciences of the United States of America 111 (45), 16219–16224. Available from: doi: 10.1073/pnas.1408886111.