2. Introduction
Rhythmicity is a wonderful phenomenon of nature.
Day night seasonal cycle, moon cycle, tidal cycle etc are example
of rhythm of nature.
Rhythmicity in behavioural activities of organism are known as
biological rhythmicity or biorhythms.
Chronos = time
Bios = Life
Logos = To study
“Study of life with respect to time is called Chronobiology”
3. The most important rhythm in chronobiology is the circadian
rhythm a roughly 24 hours.
Circadian shown by physiological process in all these organisms.
Circadian comes from the Latin; circa= around and dies; day=
approximately a day.
It is regulated by circadian clock.
The circadian rhythms can further be broken down into routine
cycles during the 24 hours day.
Diurnal:- Active day time
Nocturnal:- Active in night time
Crespercular:-Active during dawn and dusk
4. History
de Mairan described circadian
rhythms of plants in the 18th
Century.
Franz Halberg coined the term
Circadian in the 20th century.
(Circa- about or approximately;
dian- day or about 24 hour).
Considered as one of the founders
of Modern Chronobiology.
5. Biological rhythms
Circadian:- Lasting about 24 hours.
- Sleep wake cycles
Infradian:- Cycles longer than 24 hours.
- Menstrual cycle
Ultradian :- Cycles shorter than a day.
- Neuronal firing time
Seasonal:- Seasonal effective disorders.
6. Scope of Chronobiology
In medicine three disciplines take into account the
influence of time :
1. CHRONOPHYSIOLOGY
2. CHRONOPATHOLOGY
3. CHRONOPHARMACOLOGY
7. 1.CHRONOPHYSIOLOGY
•Chronophysiology is a segment in chronobiology that studies the
timely organization of physiological processes.
•The human body is subject to 24 hours rhythms.
•Indicate such as light, darkness and temperatures influence our
biological rhythm which is already set deep with in our genes.
•Hormones, neurotransmitters, sugar molecules that are
consumed and antibodies with in the blood cells show variously
alternating concentrations in the throughout the day.
•The time change for e.g. Jet lag, including problems sleeping and
concentrating, or even depression.
8. 2. CHRONOPATHOLOGY
Chronopathology deals with the subject of disrupted
timing in the vital biological processes.
It described different phenomena in the abnormality
of chronobiology sequences, as well as it
characteristics, causes , prognostic and diagnostic
significance and therapeutic implications.
9. 3. CHRONOPHARMACOLOGY
Chronopharmacology is the study of
now the effects of drugs vary with
biological timing and endogenous
periodicity.
Dosing time dependent changes also
include qualification of parameters
characterising endogenous circadian
rhythm, in terns of pharmacologic effects
