Biological rhythms in the body include ultradian (heart rate), circadian (sleep-wake cycle), and infradian (menstrual cycle) rhythms. The circadian rhythm is regulated by the suprachiasmatic nucleus in the hypothalamus and helps control sleep patterns, hormone release, body temperature, and more. Disruptions to circadian rhythms can lead to obesity, diabetes, fatigue, insomnia, and other issues. Treatments include lifestyle changes, light therapy, and medications like melatonin.

2. Biological rhythms
(periodic physiological fluctuations)
• Types of rhythms
1. Ultradian (Basic Rest-Activity Cycle) - those shorter than a
day e.g. heart beat, breathing pattern, blink rates
2. Circadian (sleep-wake cycle) - 24 hours cycle, day night cycle
3. Infradian (menstrual cycle) - >24 hours womens menstrual
cycle
All rhythms allow us to time events and
anticipate change!

3. Introduction
“ A daily rhythmic activity cycle, based on 24-hour
intervals, that is exhibited by many organisms which
helps to regulate sleep patterns, feeding behavior,
hormone release, blood pressure and body temperature,
a large proportion of our genes are regulated by the
clock ”

4. • The circadian system of an animal resembles a clock shop rather than
a single clock ” “Almost every cell in the body contains a circadian
clock ”
• This internal body clock is affected by environmental cues like
sunlight and temperature
• CR tells our body when to sleep regulate many other physiological
processes-
 Sleep wake cycle
 Body temperature
 Behavior
 Food and water intake
 Hormones
 Metabolism
 Body fluids
 Expression of genes

7. • Body has over 1000 clocks (in every organ and tissue)
• All controlled by the bodys 2 master clocks
1)SCN inside hypothalamus
2)Unidentified-regulates body temperature and alertness
• All cycles are governed by hormone released by internal body clocks
• If suprachiasmatic nucleus shut down by blindness , sleep disturbance
among visually impaired will be higher than normal incidence of sleep
disorder

8. Suprachiasmatic nucleus: the brain's
circadian clock
• SCN of the hypothalamus is directly dorsal to the optic chiasma
• One of the body's 2 major biological clocks
• Not only regulates hormones related to day /night cycle
• But orchestrates activities of many other internal clocks

9. light
retina
SCN
Pineal gland
Red Paraventricular Nucleus
Yellow Suprachiasmatic nucleus –Green
Through generating output signals that relay time-of-day information
Through gating its own sensitivity to incoming signals that adjust clock timing

12. If Circadian cycle disrupt?
• Obesity and diabetes
• Fatigue
• Disorientation
• Insomnia
• Sleep disorder
• Bipolar disorder
• Drug Effectivity

15. Circadian rhythm Sleep disorder
• Delayed sleep phase disorder (DSP)
• Advanced sleep phase disorder
• Jet lag disorder
• Shift work disorder
• Irregular sleep wake

16. Effect
1. Sleep less
2. Excessive sleepiness
3. Insomnia
4. Depression
5. Impaired work performance
6. Disrupted social schedule
7. Stressed relationship

17. Treatment
1. Life style change
2. Sleep hygiene
3. Ideal diet plan
4. Yoga , exercises and meditation
5. Well disciplinary actions in exact time
6. Bright light therapy
7. Medication such as Melatonin, modafinil , tasimelteon

18. • CR sleep disorders in persons who are totally blind
 Total blind having a tendency to cyclic form of insomnia because they lack receiving
light to the circadian time keeping system
• Feedback loop that reset master clock
• Eye is primary route by which mammalian circadian system senses light
• If optic nerve cut , lose their normal circadian rhythm
• So retina must contain light sensitive proteins other than traditional opsins
• Chemical in this receptor is made in retina and skin
• Thus skin and eyes affect the biological clocks of human
• No eyes with eyelids have more sleep problems than with low vision or those with
open eyes and normal retina

20. Thank you