Circadian Rhythm: Nature’s Intelligent clock cycle

  • Embedded deep within the brain is a master clock, Suprachiasmatic Nucleus (SCN Weaver, 1998) inside the hypothalamus that regulates the timing of many of the biological, hormonal, and behavioral processes that occur in the human body, playing a critical role in sleep, metabolism, aging and overall health and maintaining homeostatic .
  • Circadian Rhythms (CRs) are biological temporal processes that display endogenous, entrainable free-running periods that last approximately 24 h. They are driven by molecular internal clocks which can be reset by environmental light-dark cycles on a feedback loop (Edery, 2000).
  • Researchers have shown over the past few years that cellular and regional, peripheral clocks can be found in the liver, kidneys, pancreas, heart, fat and other organs and tissues that are synchronized with the sleep-wake cycle (Zylka et al., 1998). These cellular clocks regulate the activity of 3 to 10 percent (and up to 50 percent) of genes in various tissues and other parts of the body as well, by regulating the expression of clock-controlled genes (Ccg).
  • The first clock gene was isolated, or cloned, from fruit flies in 1984. Now, we have identified dozens of genes in cyanobacteria, plants, and mammals (Reppert and Weaver, 2002) that help the body keep time, including those going by such names as Clock, Per (for period) and Tim (for timeless).
  • Important genes are involved in CRs including Clock (Circadian locomotor output cycles kaput), Bmal1 (brain and muscle aryl-hydrocarbon receptor nuclear translocator-like 1), Cry1 (cryptochrome 1), Cry2 (cryptochrome 2), Per1 (Period 1), Per2 (Period 2), Per3 (Period 3), and Ccg. They organize transcription/translation autoregulatory feedback loops comprising both activating and inhibiting pathways (Reppert and Weaver, 2002; Schibler and Sassone-Corsi, 2002) forming a complex network.
  • In mammals, sleep-awake and feeding patterns, hormone secretion, heart rate, blood pressure, energy metabolism, and body temperature exhibit CRs.
  • Zeitgebers like light and food (rhythmically occurring phenomena that have primary control over circadian rhythm) for e.g. Routinely eating or sleeping at the wrong times may throw these peripheral clocks out of sync with the master clock in the brain, seen often in people with shift working, frequent trans meridian air flight, exposure to artificial light.
  • There is sufficient evidence to suggest that these chronobiological disruptions predispose individuals to the development of obesity, diabetes, cardiovascular diseases, sympathetic/parasympathetic dysfunction, hypertension, ailments of the heart and stomach, as well as various cancers, neurological and neurodegenerative diseases, and psychiatric illnesses including depression and other disorders.
  • Resynchronizing the body’s many clocks may help to restore health and proper functioning and prevention of Many chronic illnesses.
  • In the presence of light, particularly of blue wavelengths, the hormone melanopsin is produced, inhibiting the release of melatonin. at night, in the absence of light and melanopsin, melatonin is released and contributes to sleep onset.
  • During the light period, particularly in the morning, larger amounts of cortisol and insulin are released. Notably, insulin secretion and insulin sensitivity are both controlled by circadian rhythms. Insulin production diminishes and remains low throughout the day unless foods requiring insulin are consumed. During the morning, we are particularly sensitive to the action of insulin. as the day progresses, we become more resistant to insulin, and during sleep we are most insulin resistant.
  • Disruption in the circadian function leads to abnormal levels of insulin, leptin, and ghrelin, hormones affecting appetite, satiety, metabolic rate, and fat storage—a key hormone mitigating this function is melatonin.
  • Night shift workers have among the highest rates of obesity due to the presence of light at night and disordered sleep and eating rhythms.
  • Circadian disruptors related to the second zeitgeber, food, include frequent snacking, high-fat foods, late-night eating, and medications that alter sleep-wake patterns. These disruptions lead to altered melatonin production, a potent hormone that, when dysregulated, leads to insulin resistance, glucose insensitivity, and sleep disturbance. Interestingly, because food is also a driver of the circadian clock, intermittent fasting mitigates circadian dysfunction and, if performed appropriately, resets a dysregulated circadian clock.
  • CR dysfunctions in blood pressure and heart rate, are involved in arrhythmias which may lead to sudden cardiac death, myocardial infarction or stroke, often occurring at the early morning during the surge in blood pressure.
  • CRs are dissipative structures due to a negative feedback produced by a protein on the expression of its own gene (Goodwin, 1965; Hardin et al., 1990). They operate far-from- equilibrium and generate order spontaneously by exchanging energy with their external environment (Prigogine et al., 1974; Goldbeter, 2002; Lecarpentier et al., 2010).

Benefits of Fasting

Fasting affects not just are physical and mental well-being, but also are emotional and spiritual aspects of health.

Many wise ancient cultures have recommended fasting to help with achieving optimal physical, mental, emotional, spiritual health and longevity, and also freedom from disease utilizing intermittent, periodic or seasonal fasting.

Yogic philosophy recommends and encourages to keep a fast on a particular day of the week or month based on your spiritual intentions. (for e.g. Monday or Thursday, or on a full moon day and 11th night of the lunar cycle). It is recommended not only to practice food abstinence on the spiritual fasting day, but also cultivate mindfulness and a positive attitude to help with spiritual progression. Sadhana is the discipline of routine spiritual practice and the surrendering of the ego to the higher self.

The Benefits of Fasting

Fasting, when done correctly, positively affects our physical, energetic, mental, emotional, and spiritual aspects, since we are much more than just the body and mind.

Fasting has shown to have the following health benefits, and more:

  1. Helps with weight loss, leading to physical Lightness, and increasing energy level. Fasting allows the body to use fat as it’s primary source of energy instead of sugar, enabling many athletes to hit low body fat percentages for competitions.
  2. Improving mental clarity, alertness and moods, decrease in depression and anxiety and improves subjective feelings of wellbeing.
  3. Resetting the metabolic button, improving metabolism of sugars and fats.
  4. Resting and healing the digestive system, helping with GI symptoms including IBS, food intolerances, constipation, acidity, gas, bloating.
  5. Revitalizing the immune system, helping with stabilizing many autoimmune diseases, Arthritis, IBD, Parkinson’s, Alzheimer’s dementia etc.
  6. Facilitating the natural detoxification and cleansing of the body, including the liver and the GI tract.
  7. Helps prevent and reverse several medical conditions like hypertension, hyperlipidemia, obesity, diabetes type 2, autoimmune diseases, clarifying skin problems. (More on detailed medical benefits, and the reasoning behind them.)
  8. It helps improve self-discipline and form long-term good eating habits and patterns.
  9. Creates mindfulness in eating patterns, controlling overindulgences of senses.
  10. It helps with emotional eating and food cravings too, since it enables one to rise above and beyond the set emotional patterns strengthens will power and self-confidence.
  11. It helps promote an inner stillness, and better alignment with out spiritual purpose in life.


Read here for the Scientific evidence of benefits of Fasting