Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Biological Clocks and Seasonal Responses02:45

Biological Clocks and Seasonal Responses

42.1K
The circadian—or biological—clock is an intrinsic, timekeeping, molecular mechanism that allows plants to coordinate physiological activities over 24-hour cycles called circadian rhythms. Photoperiodism is a collective term for the biological responses of plants to variations in the relative lengths of dark and light periods. The period of light-exposure is called the photoperiod.
42.1K
Circadian Rhythms and Gene Regulation02:19

Circadian Rhythms and Gene Regulation

4.7K
The biological clock is involved in many aspects of regulating complex physiology in all animals. It was in 1935 when German zoologists, Hans Kalmus and Erwin Bünning, discovered the existence of circadian rhythm in Drosophila melanogaster. However, the internal molecular mechanisms behind the circadian clock remained a mystery until 1984, when Jeffrey C. Hall, Michael Rosbash, and Michael W. Young discovered the expression of the Per gene oscillating over a 24-hour cycle. In subsequent...
4.7K
Circadian Rhythms and Gene Regulation02:19

Circadian Rhythms and Gene Regulation

2.5K
2.5K
Chronopharmacokinetics: Circadian Rhythms and Influence on Drug Response01:15

Chronopharmacokinetics: Circadian Rhythms and Influence on Drug Response

479
Circadian rhythms are cyclic changes that are crucial in plasma drug concentrations. Various standard circadian parameters, including core body temperature, heart rate, and other cardiovascular factors, directly impact disease states and the therapeutic response to drug therapy.
The time of drug administration is an important factor to consider, as it can influence the toxic dose of a drug. For example, a study conducted by Prins et al. in 1997 examined the effects of the timing of...
479
Global Climate Change01:50

Global Climate Change

29.8K
Throughout its ~4.5 billion year history, the Earth has experienced periods of warming and cooling. However, the current drastic increase in global temperatures is well outside of the Earth’s cyclic norms, and evidence for human-caused global climate change is compelling. Paleoclimatology, the study of ancient climate conditions, provides ample evidence for human-caused global climate change by comparing recent conditions with those in the past.
29.8K
Apparent Weight and the Earth's Rotation01:28

Apparent Weight and the Earth's Rotation

4.4K
Since all objects on the Earth's surface move through a circle every 24 hours, there must be a net centripetal force on each object, directed towards the center of that circle. The points of the north and south poles are the only exception to this rule.
For an object on the Earth's equator, the net centripetal force that accounts for its rotation is the Earth's pull towards its center, or the weight minus the normal force that prevents it from piercing into the Earth's surface....
4.4K

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Author Correction: How can social jetlag affect health?

Nature reviews. Endocrinology·2026
Same author

Reflections of a conceptualist.

Npj biological timing and sleep·2026
Same author

Sleep and activity patterns in autism.

Autism : the international journal of research and practice·2026
Same author

Challenges and Recommendations for Integrating Circadian Medicine in Critical Care: A Roadmap.

Chest·2025
Same author

The Pittendrigh-Aschoff Lecture 2024.

Journal of biological rhythms·2025
Same author

Chronotype-specific changes in subjective sleep quality: Differential responses to the relaxation of social time pressure in Japan.

Chronobiology international·2025

Related Experiment Video

Updated: Apr 1, 2026

Human Circadian Phenotyping and Diurnal Performance Testing in the Real World
10:16

Human Circadian Phenotyping and Diurnal Performance Testing in the Real World

Published on: April 7, 2020

9.2K

Having Trouble Typing? What on Earth Is Chronotype?

Till Roenneberg1

  • 1Institute of Medical Psychology, Ludwig Maximilian University, Munich, Germany roenneberg@lmu.de.

Journal of Biological Rhythms
|October 9, 2015
PubMed
Summary

This commentary clarifies two distinct chronotype assessment methods: the Morningness/Eveningness Questionnaire (MEQ) for daily preferences and the Munich ChronoType Questionnaire for circadian rhythm phase. Understanding their differences is crucial for appropriate research application.

Keywords:
MCTQMEQ

More Related Videos

Collecting Sleep, Circadian, Fatigue, and Performance Data in Complex Operational Environments
08:36

Collecting Sleep, Circadian, Fatigue, and Performance Data in Complex Operational Environments

Published on: August 8, 2019

13.0K
Parallel Measurement of Circadian Clock Gene Expression and Hormone Secretion in Human Primary Cell Cultures
06:53

Parallel Measurement of Circadian Clock Gene Expression and Hormone Secretion in Human Primary Cell Cultures

Published on: November 11, 2016

8.9K

Related Experiment Videos

Last Updated: Apr 1, 2026

Human Circadian Phenotyping and Diurnal Performance Testing in the Real World
10:16

Human Circadian Phenotyping and Diurnal Performance Testing in the Real World

Published on: April 7, 2020

9.2K
Collecting Sleep, Circadian, Fatigue, and Performance Data in Complex Operational Environments
08:36

Collecting Sleep, Circadian, Fatigue, and Performance Data in Complex Operational Environments

Published on: August 8, 2019

13.0K
Parallel Measurement of Circadian Clock Gene Expression and Hormone Secretion in Human Primary Cell Cultures
06:53

Parallel Measurement of Circadian Clock Gene Expression and Hormone Secretion in Human Primary Cell Cultures

Published on: November 11, 2016

8.9K

Area of Science:

  • Chronobiology
  • Sleep Science
  • Psychometrics

Background:

  • Chronotype assessment is vital in sleep and chronobiology research.
  • Existing questionnaires may yield different types of chronotype information.
  • Distinguishing between these measures is essential for accurate interpretation.

Purpose of the Study:

  • To differentiate between two primary methods of chronotype assessment: the Morningness/Eveningness Questionnaire (MEQ) and the Munich ChronoType Questionnaire (MCQ).
  • To highlight the distinct outputs and underlying constructs measured by each questionnaire.
  • To guide researchers in selecting the appropriate tool based on study objectives.

Main Methods:

  • Conceptual analysis and historical context of chronotype questionnaires.
  • Comparison of the scoring and interpretation of MEQ (preference score) versus MCQ (phase of entrainment time).
  • Discussion of the validity and appropriate application of each instrument.

Main Results:

  • The MEQ assesses subjective daily preferences for morning or evening activity.
  • The MCQ estimates the objective phase of circadian entrainment.
  • While correlated in populations, these measures represent different aspects of chronotype.

Conclusions:

  • MEQ and MCQ measure fundamentally different constructs and should not be conflated.
  • Researchers must choose the questionnaire that aligns with their specific research question regarding chronotype.
  • Appropriate use of these tools enhances the validity and interpretability of chronobiology studies.