Till Roenneberg (born 4 May 1953) is a professor of
chronobiology
Chronobiology is a field of biology that examines timing processes, including periodic (cyclic) phenomena in living organisms, such as their adaptation to solar- and lunar-related rhythms. These cycles are known as biological rhythms. Chronobi ...
at the Institute of Medical Psychology at
Ludwig-Maximilian University (LMU) in
Munich, Germany
Munich ( ; german: München ; bar, Minga ) is the capital and most populous city of the German state of Bavaria. With a population of 1,558,395 inhabitants as of 31 July 2020, it is the third-largest city in Germany, after Berlin and Ha ...
. Roenneberg, in collaboration with
Martha Merrow, explores the impact of light on human
circadian rhythm
A circadian rhythm (), or circadian cycle, is a natural, internal process that regulates the sleep–wake cycle and repeats roughly every 24 hours. It can refer to any process that originates within an organism (i.e., Endogeny (biology), endogeno ...
s, focusing on aspects such as
chronotype
A chronotype is the behavioral manifestation of underlying circadian rhythm's myriad of physical processes. A person's chronotype is the propensity for the individual to sleep at a particular time during a 24-hour period. ''Eveningness'' (delayed ...
s and social
jet lag
Jet lag is a physiological condition that results from alterations to the body's circadian rhythms caused by rapid long-distance trans-meridian (east–west or west–east) travel. For example, someone flying from New York to London, i.e. fr ...
in relation to health benefits.
Life
Roenneberg was born in Munich, Germany. He began working with
Jürgen Aschoff
Jürgen Walther Ludwig Aschoff (January 25, 1913 – October 12, 1998) was a German physician, biologist and behavioral physiologist. Together with Erwin Bünning and Colin Pittendrigh, he is considered to be a co-founder of the field of chronobio ...
at the age of 17.
Roenneberg attended both the University College London and Ludwig Maximilian University of Munich where he began by studying
physics
Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...
. He switched to medicine in order to focus on the science of the human body, but ended up studying
biology
Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary i ...
. As a
postdoctoral fellow
A postdoctoral fellow, postdoctoral researcher, or simply postdoc, is a person professionally conducting research after the completion of their doctoral studies (typically a PhD). The ultimate goal of a postdoctoral research position is to p ...
, he studied again under Jürgen Aschoff, studying annual rhythms in the body, then moved to the United States to study the cellular basis of biological clocks under
Woody Hastings at
Harvard University
Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of higher le ...
.
In 1991, he began the tradition of giving the Aschoff's Ruler prize to a chronobiologist who has advanced the field.
He is currently the vice-chair of the Institute for Medical Psychology of the Ludwig Maximilian University of Munich, the head of the Centre for Chronobiology, the president-elect of the European Biological Rhythms Society, the president of the World Federation of Societies for Chronobiology, and a member of the Senior Common Room of Brasenose College, University of Oxford. From 2005 to 2010 he was the coordinator of "EUCLOCK" and coordinator of the Daimler-Benz-Foundation network "ClockWORK", and from 2010 to 2012 was the member at large of the Society for Research of Biological Rhythms
Work
Early work
Dinoflagellates
Aside from human
chronobiology
Chronobiology is a field of biology that examines timing processes, including periodic (cyclic) phenomena in living organisms, such as their adaptation to solar- and lunar-related rhythms. These cycles are known as biological rhythms. Chronobi ...
, Roenneberg has significantly contributed to other aspects of the chronobiology field. He has done extensive work on
dinoflagellates
The dinoflagellates (Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates are ...
, a
unicellular
A unicellular organism, also known as a single-celled organism, is an organism that consists of a single cell, unlike a multicellular organism that consists of multiple cells. Organisms fall into two general categories: prokaryotic organisms and ...
organism, and has been able to show that even this simple organism is capable of possessing two independent rhythms, providing evidence that a single cell can have two different oscillators. In addition, his work on dinoflagellates has been able to show that these two independent oscillators differ to a significant extent in that they respond differently when treated with various light pulses. They found that the two oscillators have varying sensitivities to different types of light. The B-oscillator is most sensitive to blue light while the A oscillator is sensitive to both blue and red light.
''Neurospora crassa''
Roenneberg has also completed work on
Neurospora crassa
''Neurospora crassa'' is a type of red bread mold of the phylum Ascomycota. The genus name, meaning "nerve spore" in Greek, refers to the characteristic striations on the spores. The first published account of this fungus was from an infestation ...
, determining the masking qualities of
entrainment
Entrainment may refer to:
* Air entrainment, the intentional creation of tiny air bubbles in concrete
* Brainwave entrainment, the practice of entraining one's brainwaves to a desired frequency
* Entrainment (biomusicology), the synchronization o ...
through a
Frequency (gene)
The frequency (''frq'') gene encodes the protein frequency (FRQ) that functions in the ''Neurospora crassa'' circadian clock. The FRQ protein plays a key role in circadian oscillator, serving to nucleate the negative element complex in the auto r ...
-null circadian oscillator. He observed in the period of spore production (
conidia
A conidium ( ; ), sometimes termed an asexual chlamydospore or chlamydoconidium (), is an asexual, non-motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word for dust, ('). They are also called mitospores due to the ...
bands) the phenomenon of masking, an unexpected effect on circadian entrainment due to a particular
zeitgeber
A zeitgeber () is any external or environmental cue that entrains or synchronizes an organism's biological rhythms, usually naturally occurring and serving to entrain to the Earth's 24-hour light/dark and 12-month cycles.
History
The term ' (; ) ...
(such as light or temperature). Masking has significant implications not only for future studies – which must attempt to demask affected data – but also in relation to entrainment in everyday life.
Current work
Chronotype questionnaire
One of Till Roenneberg's most renowned accomplishments is the development of the
Munich Chronotype Questionnaire
The Munich Chronotype Questionnaire (MCTQ) was created in 1976 by Till Roenneberg and Martha Merrow at Ludwig-Maximilians University
The Ludwig Maximilian University of Munich (simply University of Munich or LMU; german: Ludwig-Maximilians-Uni ...
(MCTQ). As a collaboration with Martha Merrow at LMU Munchen, the MCTQ samples sleep and circadian rhythm data from more than 25,000 participants. Unlike other chronotyping methods, which address the psychology of sleep, the MCTQ measures the
phase angle of entrainment
Phase or phases may refer to:
Science
*State of matter, or phase, one of the distinct forms in which matter can exist
*Phase (matter), a region of space throughout which all physical properties are essentially uniform
*Phase space, a mathematica ...
, the difference between an organism's intrinsic circadian period and the environmental light cycle. Thus, this questionnaire is the first to use a biological foundation, rather than psychology to determine the basis of sleep schedules.
Questions about work day and free day sleep schedules, work details, and lifestyle provide data to aid in the understanding of the interplay of biological clocks and social influences. Such research has led Roenneberg to his theory of social jet lag. The MCTQ categorizes each participant into one of seven chronotype groups and utilizes data on participants’ midsleep phase and
sleep debt
Sleep debt or sleep deficit is the cumulative effect of not getting enough sleep. A large sleep debt may lead to mental or physical fatigue, and can adversely affect one's mood, energy and ability to think clearly.
There are two kinds of sleep ...
to survey what “type” of sleeper each person is, such as late sleepers, slightly late sleepers, early sleepers, and others. From these data, the MCTQ offers methods to make up for sleep debt (if any), and offers suggestions on what to do to wake up earlier or sleep later.
This chronotype questionnaire is important because it delves into the social aspects of circadian rhythms. By testing behavior rather than directly testing genetic factors, the MCTQ may offer new information regarding how the effects of external factors, including geographic location, seasons, obesity, social jet lag, or shift work, may relate to genetic predispositions of circadian rhythms.
Internal time
Roenneberg released a book in March 2012 titled ''Internal Time: Chronotypes, Social Jet Lag, and Why You're So Tired'' where he explains the concepts behind circadian rhythm to the masses. One of the major points in his book is, "Early birds and night owls are born, not made."
Roenneberg wanted to rid people of labels such as "lazy" that frequently get placed upon those who wake up late. With this book, he wanted to deliver his point that these sleep patterns are due to people's
genetics
Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar wor ...
and are not from choice. He discusses how everyone is born with an internal clock, and living a lifestyle in dissonance with this inherent biological clock puts individuals at greater risk for health problems. Roenneberg introduces the term “social jet lag," saying it is more dangerous than normal
jet lag
Jet lag is a physiological condition that results from alterations to the body's circadian rhythms caused by rapid long-distance trans-meridian (east–west or west–east) travel. For example, someone flying from New York to London, i.e. fr ...
because social jet lag forces individuals to persistently go against their biological clock in a consistent light/dark cycle. In this book, he defines social jet lag as “the difference between midsleep on free days and midsleep on work days." Free days are defined as days without an alarm clock, where one naturally wakes up, and work days where one wakes up with an alarm clock. Midsleep is defined as the
midpoint
In geometry, the midpoint is the middle point of a line segment. It is equidistant from both endpoints, and it is the centroid both of the segment and of the endpoints. It bisects the segment.
Formula
The midpoint of a segment in ''n''-dimens ...
of an individual's sleeping period. One of the significant health risks of social jet lag is
obesity
Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it may negatively affect health. People are classified as obese when their body mass index (BMI)—a person's we ...
, and Roenneberg claims that for every hour of social jet lag, the probability of being overweight increases by approximately 33%. In fact, social jet lag is so prevalent that Roenneberg claims that 87% of the population of
Central Europe
Central Europe is an area of Europe between Western Europe and Eastern Europe, based on a common historical, social and cultural identity. The Thirty Years' War (1618–1648) between Catholicism and Protestantism significantly shaped the area' ...
suffers from social jet lag to some degree.
Roenneberg also claims that
adolescents
Adolescence () is a transitional stage of physical and psychological development that generally occurs during the period from puberty to adulthood (typically corresponding to the age of majority). Adolescence is usually associated with the te ...
, biologically, have an internal clock that causes their midsleep to fall later than young infants and adults. Thus, teenagers are not lazy, but are simply following their internal rhythms by going to sleep later and waking up later. This late midsleep pattern changes after adolescence, but at different points for men and women. Women's midsleep changes around age eighteen, while men's midsleep changes at the age of twenty-one. Forcing teenagers to wake up early, against their internal rhythms, leads to stress. As many studies have shown, stress leads to unhealthy decisions such as smoking and drinking.
Awards
* Harvard-Hoops Price for Excellence in Teaching
* Honma Prize for Outstanding Contributions to Chronobiological Research
* Silver Medal of the University of Munich
* Professional Lighting Design Recognition Award for Research and Education
Selected publications
Some of Roenneberg's publications include:
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References
External links
MCTQ Chronotype Questionnaire"Internal Time" by Till Roenneberg*
European Biological Rhythms SocietyEUCLOCKSociety for Research on Biological Rhythms*
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{{DEFAULTSORT:Roenneberg, Till
20th-century German biologists
Chronobiologists
Ludwig Maximilian University of Munich faculty
Harvard University alumni
Living people
1953 births
Alumni of University College London
Scientists from Munich
21st-century German biologists