The study of chronobiology deals with the study of time in relation to living organisms. Three American scientists Jeffrey C. Hall, Michael Rosbash and Michael W. Young were awarded the Noble prize in 2017 for their outstanding discovery of microscopic biological machinery that controls the circadian rhythm, or the 24-hour body clock. Started approximately in 1960s and first acknowledged in the 1700s by examining the movement of plant leaves, it is now getting updated with the latest research and techniques.

Cycles of chronology

The basic cycles of chronobiology are: 1) Infradian Rhythms lasts more than 24 hours and repeated only every few days, weeks, months, or even once per year.

2) Ultradian Rhythms are the biological rhythms which are “shorter than 24-hours. There are many physiological functions of the human body that exemplify an ultradian rhythm and have multiple cycles in one day. An adult, for example, has an exertion and rest cycle about every two hours.”

3) Circadian Rhythms take approximately 24-hours, i.e. the human sleep/wake cycle or the leaf movements of plants. (

Areas of application

Chronobiology is being used today in the study of genetics, endocrinology, ecology, sports medicine and psychology and in many more fields. The study of circadian rhythm is the most widespread area of research in chronobiology as it directly affects a human’s body. Many living things like human, plants, animals follows a circadian rhythms. Hence “Thousands of studies have yielded information on how the precise timing of a medication or supplement can decrease side effects, have a more potent effect on the target organ system or disease and even completely disrupt a physiological process” (

Shift work

One the main areas of application of this study is in shift work and the health problems it poses. Industries such as BPOs, healthcare and hospitals, military, media, fire stations, transportations need to work in shifts. “Working at night runs counter to the body’s natural circadian rhythm, says Charmane Eastman, PhD, a physiological psychologist at Rush University in Chicago”. (

Sleep, wake and other daily activities are the responses of our circadian rhythms which are followed by the body’s internal or biological clock and hence, working in shift work or a rotational shift work may create a disorder in our health. Few of us choose night shift as a child care perspective and few of us join it for a better salary but there are many who have to do it. A weekly peer reviewed journal ‘BMJ’ says that “One of the most important physiological problems associated with shift work and the night shift in particular, is that working, eating, and sleeping phases are changed.” (

Shift work and sleep disorder, risk of obesity, cancer

Chronic sleep disorder can be caused due to rotational sleep, early morning shift or night shift works. On this the National Sleep Foundation says that “a person never catches up on needed sleep and carries a significant “sleep debt. This kind of chronic loss of sleep has serious implications for health, productivity, and safety.” (

Shift work / night shift sometime lead to health issues like heart attack, diabetes, stomach problem, ulcers, depression and cancer. (

“A study reported by Medical News Today  last year, for example, found a link between rotating night shift work and increased risk of death from cardiovascular disease, lung cancer, and all causes.” ( Science Daily says that, “Female night shift workers may have increased risk of common cancers”. ( Night shift work is sometimes harmful for women which causes breast, gastrointestinal and lung cancer. “Scientists from the Massachusetts Institute of Technology (MIT) reveal that disruption to the circadian rhythm also leads to the impairment of two tumor suppressor genes, which can spur tumor growth.” (

Current Research topics in Chronobiology

Students may refer a journal ResearchGate which provides all information about the research in chronobiology. The journal ‘Frontiers’ has focused on the research topic Sleep and Chronobiology in Plasticity and Memory and said that “factors which contribute to adaptive responses to changing environmental stimuli are likely derived from basic evolutionarily ancient processes, and underscores the importance of using both invertebrate and vertebrate models to study the interaction of chronobiology and cognitive processing.”  (  The University of Zurich offers research in Molecular Biomarkers and Mechanisms for Sleep and Circadian Dysfunction which focuses on sleep and our daily routine are the brain – centered processes and are the signaling pathways. Disruptions in these pathways may lead to a cause of cancer. The university says that, “In reverse, these disorders, as well as stress and infection, directly impair sleep and circadian function. In some cases like colorectal cancer, timed circadian therapy has been associated with significant improvement in therapeutic outcome” (

The Gordon Research Conference held in 2017 had focused on Circadian Regulation Across Physiological Systems, Lifespan and Pathological Conditions. (

The Psychophysiology and Chronobiology Research Group at the Semmelweis University focuses on the sleep research in relation to sleep, behaviour and psychological phenomena. Like Sleep EEC, cognition and personality where the focus is on the “sleep related brain electric activity correlates of aging, general and specific cognitive abilities, personality and trait – like affective styles, including attachment”. The research group wants to find new opportunities by “latest EEG analysis methods to reveal the hitherto hidden aspects of the central neural activity in function of age, cognition, personality and mental health and also to correlates these data with volumetric Magnetic Resonance Imaging assessed brain morphology. ( Another area of research is the Neurophysiology and psychobiology of sleep and wakefulness where the focus is on the phenomena’s like sleep – waking states and phasic phenomena and the controversial issues like the hippocampal rhythmic slow activity in humans. ( The research groups also focuses on the topics like Dreams and Dreaming, Development of sleeping, Development of Dreaming. ( Methodological Aspects of Shift Work Research: One of the leading Taylor & Francis said in its article reviews “a number of common methodological issues which are of relevance to epidemiological studies”. (

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