128 LIGHT + TECH
This year’s winner of the Daylight Research award is a pioneer in the field: Till Roenneberg, emeritus professor of chronobiology at the Institute of Medical Psychology at Ludwig-Maximilian University (LMU) in Munich. Roenneberg has dedicated most of his career to investigating the effects of light on circadian clocks, sleep and health, coining the term ‘social jetlag’ along the way. The recipient of numerous international awards and honorifics, he founded Chronsulting in 2015 with the aim of translating his experience of almost 50 years of clock and sleep research to the real world. He began working on biological rhythms with German physician, biologist and behavioural physiologist Jürgen Aschoff, considered to be a co-founder of the field of chronobiology, at the age of 17. After studying biology in Munich (LMU) and London (UCL), he worked at Harvard. His work spans the natural and social sciences, and his research and publications have promoted understanding of the many aspects and impacts of daylight, and lighting in general, for human health, well-being and performance. His findings have been influential, said the jury, and applied to a number of fields including medicine, public policy and architecture. Roenneberg pioneered the epidemiology of chronotypes (the relationship between the circadian clock and the natural daylight-dark cycle: the now familiar larks and owls). He showed, for example, that the relative timing of human entrainment (‘chronotype’) changes with age (which, for instance, puts the late-hour preferences of teenagers in a biological perspective) and
with day length. This was applied practically when he worked with the steel industry to evaluate and allocate workers to their chronotype-specific shift. This change resulted in significantly improved sleep for most individuals. All organisms, from primitive
bacteria to human beings, have a biologically determined, internal body clock and it is his work with these diverse groups of organisms – including algae and fungi – that has characterised his interdisciplinary approach, said jurors, allowing him ‘to take novel approaches to address key questions relating to the effects of daylight on human health, well-being and performance’. ‘He was one of the first
chronobiologists to appreciate that both the intensity and the spectral composition of light was key in understanding how light affects the circadian system in a range of organisms,’ they continued. After establishing key concepts related to light and circadian rhythms, Roenneberg moved to human and social sciences, with a focus on daylight. He used his experience in lab-based chronobiology and big data to address research questions that focused on human daily behaviour in real life. In 1976, he developed a new questionnaire – the Munich ChronoType Questionnaire (MCTQ) – to enable investigations of circadian entrainment in populations across the world. The resulting database has more than 400,000 entries and has allowed him to investigate important questions in ‘real-life experiments’.
A key observation by Roenneberg, said the jury, is the demonstration that human clocks remain profoundly
influenced by the natural light/dark cycle, despite increasing urbanisation. His ‘social jetlag’ concept, the difference in sleep timing between work and free days, reflects changes individuals must make for work patterns that are counter to their natural biology.
While social jetlag is an apparently innocuous term, when it is prolonged it becomes a biological challenge to an individual’s circadian and sleep systems, discovered Roenneberg, who went on to link it with obesity, depression and substance abuse.
He has continued to demonstrate the importance of daylight on human circadian rhythms and sleep in longitudinal studies of humans living in different environments. He has shown that circadian clocks resist the artificial social clock changes associated with Daylight Saving Time (DST) as compared with Standard Time (ST) when social clocks and daylight are more aligned. In his recent work, he has studied how industrialisation (with its associated changes in exposure to daylight versus artificial light) influences circadian rhythms and sleep. This has involved studying communities in Brazil, such as the Quilombolas, whose lifestyles range from rural (and without electricity) to modern urban.
The jury was ‘deeply impressed’ by Roenneberg’s fundamental research findings, their application to help resolve real-world issues and his ability to communicate this work to both scientific and public audiences. ‘He is an exemplary scientist,’ said the judges. ‘With energy and enthusiasm, he applies innovative approaches to understand the importance of natural light on human health.’
SOCIAL JETLAG
‘Our lives are governed by three clocks: the social clock that organises our lives with others (local time), the biological clock that controls our physiology (circadian time) and the sun clock that defines natural light and darkness. The more misaligned these clocks are, the higher our odds of developing certain diseases. “Social jetlag” quantifies the difference between local and circadian time.’
Till Roenneberg
‘In the old days, before we had industrialisation and before we had electrical light, or artificial light, we had practically no light during the night, after sunset, and we had an enormous amount of light when we went outside, which most of us did in that era because we were agriculturally or otherwise occupied. If we go outside on a rainy day, we get about 10,000 lux or more. Lux is just a dimension
that we use to measure light intensity. On a clear sky day, we get over a hundred thousand lux. If we stay inside, which we have done for the past 100 years, because we are working, either in factories or in ofices, we can be lucky if we get 400 lux. So it’s a fraction of the light that we used to get during the day. But we are not so lucky to still get something like 100 to 200 lux after sunset
because we’re switching on lights when our clocks used to have darkness. The clocks are set by light and darkness, and if you have very strong light during the day and no light during the night, this is what we call a very strong time giver to signal for the clock to set itself. We have weakened that time giver enormously by not going outside during the day, and by switching on light
during the night. For most of us that meant that our clocks had to become later, in order to still synchronise to the 24-hour day. And that is always forgotten. Although we all know it without thinking about it.
Our clocks are so late
that over 80% of the population need an alarm clock to wake up in the morning. Now if you need an alarm clock to wake up in the morning, your
biology hasn’t slept to the end. Because your clock is late and you have to wake yourself up in order to go to work, or to school. The important thing is
that this is really light dependent. Our internal clocks cannot be set by the alarm that goes off on the mobile phone, or any other alarm. It’s light and darkness that set our clocks.’
Till Roenneberg, edited extract from
project-sleep.com interview
RIGHT: THE DAYLIGHT AWARD BELOW: MIKE PELLINNI/
SHUTTERSTOCK.COM PREVIOUS SPREAD:
JAVIERCALLEJAS.COM
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