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Related Concept Videos

Aging01:26

Aging

Aging is a complex biological phenomenon influenced by various processes that affect cellular and systemic functions. Several prominent theories attempt to explain its mechanisms, highlighting cellular limitations, oxidative damage, and hormonal changes as central factors in aging.
Cellular Clock Theory
The cellular clock theory posits that the human lifespan is closely tied to the finite capacity of cells to divide, a phenomenon governed by telomeres, which are protective caps at the ends of...
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Biological Clocks and Seasonal Responses

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.
The Effect of Aging on Tissues01:19

The Effect of Aging on Tissues

Several body functions deteriorate with age. The external signs of aging are easily identifiable. For example, the skin becomes dry, less elastic, and thins out, forming wrinkles. The skin of the face begins to appear looser due to a decrease in the levels of elastic and collagen fibers in the connective tissue. Additionally, melanin production in the hair follicle decreases with age, resulting in gray hair. Moreover, the senses of sight and hearing decline, so glasses and hearing aids may...
Circadian Rhythms and Gene Regulation02:19

Circadian Rhythms and Gene Regulation

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 years,...
Circadian Rhythms and Gene Regulation02:19

Circadian Rhythms and Gene Regulation

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 years,...
Chronopharmacokinetics: Time-Dependent Pharmacokinetics01:20

Chronopharmacokinetics: Time-Dependent Pharmacokinetics

Chronopharmacokinetics studies the temporal change in drug absorption and elimination. These changes can be cyclical or non-cyclical. Cyclical changes occur over a regular interval, while non-cyclical changes occur over a longer, irregular period.
Time-dependent pharmacokinetics refers to non-cyclical changes in drug rate processes over a period of time. It can lead to nonlinear pharmacokinetics, where the relationship between drug concentration and time is not proportional. Non-cyclical...

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Related Experiment Video

Updated: Jun 24, 2026

Measuring Single-Cell Aging with an Imaging-based Biomarker of Chromatin and Epigenetic Aging
09:10

Measuring Single-Cell Aging with an Imaging-based Biomarker of Chromatin and Epigenetic Aging

Published on: January 30, 2026

Chronomics, human time estimation, and aging.

Franz Halberg1, Robert B Sothern, Germaine Cornélissen

  • 1Halberg Chronobiology Center, University of Minnesota, Campus Mail Code 8609-MMC 8609, 420 Delaware St. S.E., Minneapolis, MN 55455, USA. halbe001@umn.edu

Clinical Interventions in Aging
|March 14, 2009
PubMed
Summary
This summary is machine-generated.

Circadian rhythm stage significantly impacts mental aging. Over decades, time estimation changed, with morning estimates shortening and evening estimates lengthening, influenced by long-term biological cycles.

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Quantifying Yeast Chronological Life Span by Outgrowth of Aged Cells
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Quantifying Yeast Chronological Life Span by Outgrowth of Aged Cells

Published on: May 6, 2009

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Last Updated: Jun 24, 2026

Measuring Single-Cell Aging with an Imaging-based Biomarker of Chromatin and Epigenetic Aging
09:10

Measuring Single-Cell Aging with an Imaging-based Biomarker of Chromatin and Epigenetic Aging

Published on: January 30, 2026

Quantifying Yeast Chronological Life Span by Outgrowth of Aged Cells
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Published on: May 6, 2009

Area of Science:

  • Chronobiology
  • Human Aging
  • Biomedical Science

Background:

  • Circadian rhythm stage influences various outcomes, notably mental aging.
  • Understanding age-related changes in biological rhythms is crucial.

Purpose of the Study:

  • To map and analyze circadian and infradian rhythms in a healthy individual over 35 years.
  • To investigate age-related alterations in time perception linked to biological rhythms.

Main Methods:

  • Longitudinal analysis of self-assessed 1-minute time estimations (approx. 5 times/day for 1 year) from age 25 to 60.
  • Application of the extended cosinor method to analyze detected cycles.

Main Results:

  • First-time mapping of weekly, monthly, semi-annual, and annual cycles in time estimation.
  • Significant differences in time estimation between ages 25 and 60, particularly in the morning.
  • A linear decrease in morning estimation time and an increase in evening estimation time observed, modulated by a -33.6-year cycle.

Conclusions:

  • Circadian and infradian rhythm mapping is vital for scrutinizing aging effects.
  • Specific infradian components (approx. 30-day, circannual) present at age 25 were absent later; longer cycles emerged.
  • Rhythm stages may serve as markers for timing therapeutic interventions in disease.