The ayurvedic scholars and yogis knew the circadian rhythms long before the French geophysicist and astronomer, Jean-Jacques d’Ortous de Mairan, coined the term in 1719. The daily sadhana practices, are the external observances ayurvedic practitioners engage in, in order to maintain the synchronicity of our circadian rhythms. The daily sadhana practices, are collectively referred to as dinacharya. Dina means ‘day’ and acharya means, ‘to follow.’ As ayurvedic practitioners, we follow cues observed in nature with our behavior, so that our circadian rhythm is in line with the earth’s rotation. Ayurveda has taught, when we are out of sync with this rhythm, disease and imbalance can develop. Today it is known that circadian rhythm disharmony contribute to, and potentially cause, mood disorders such as depression, bi-polar disorder, adhd, and physical diseases such as heart disease, obesity, epilepsy, cancer, and Parkinson’s disease. Conversely, if we are able to align our circadian rhythm, we can maximize our health, mental alertness, immunity, awareness, and physical strength.
Our body’s ‘master clock’ that keeps the time of circadian rhythm is called the suprachiasmatic nuclei (SCN). It is found on the hypothalamus in the brain in many types of living creatures. Proteins called cryptochrome 1 & 2, originally discovered in plants, are also in the human eye, and respond to ranges from blue to ultraviolet on the light spectrum. When this light enters the eye it activates neurons that transform photons (light particles) into electrical signals, are then sent to the SCN. In response, the SCN suppresses the pineal gland from secreting the hormone melatonin when it is light, and stimulates melatonin secretion, when it is dark. Melatonin is an important hormone and antioxidant, responsible for stimulating the desire to sleep when it is secreted.
The circadian rhythms in the periphreal tissues are called “oscillators.” Upon our first exposure to light in the morning, the SCN informs the other cells in the rest of the body, who then augment their circadian rhythm accordingly. The SCN communicates its circadian signals, through several mediums such as the pituitary hormones and vagus nerve, to the peripheral tissues, such as the liver, kidneys, and gastrointestinal tract. The peripheral tissue oscillators integratively maintain numerous circadian rhythms in the body, such as respiration, temperature, hunger, tiredness and wakefulness.
Dusk and dawn are the most important zeitgebers to almost every living organism, including bacteria, animals, plants, and humans, on the planet. If the initial light exposure is different consistently over a period of time, circadian rhythms will shift. In normal circumstances this assists in our adjustment to seasonal changes. The sleep/wake cycle is the first circadian rhythm to shift to changing light exposures. The oscillators in the peripheral tissues take several days longer. This is harmless if it occurs slowly over time. When there are abrupt changes to light exposure, however, it is observed to cause imbalance. Researchers speculate that travel and dramatic schedule changes, can pose risks to circadian rhythm synchronicities. When circadian cycles in the peripheral tissues run autonomously from the SCN, they ‘free run,’ and the rhythms become ‘desynchronized.’ This desynchronization is observed in a wide variety of diseases. In clinical studies, cells taken from the SCN, and kept away from alternating exposure of light and darkness, continued its circadian cycle for up to 31-days before it began to ‘’free run.’’ It moved from the normal 24-hour cycle, to a 26-hour cycle. Cells taken from peripheral tissues ceased their circadian rhythm in only 9 days.
The pineal gland is a primary component in the sleep/wake cycle. It is primarily known for its secretion of melatonin, and is associated with the third eye in many Eastern traditions. Melatonin is a hormone that circulates through the body of many animals, and is believed to entrain the circadian rhythms of several biologic functions.It is sometimes called the ‘’hormone of darkness’’ because it triggers the desire for sleep. It is known to affect sleep cycles, circadian rhythms, suppress tumor growth, and act as a powerfult antioxidant. In healthy humans, it is secreted at low levels in dim light, and gradually increases over the next several hours, with peaks mid-sleep cycle.
Melatonin has been studied and used in the treatment of several diseases, including, cancer, immune disorders, sleep disorders, cardiovascular disease, and others. Artificial light from computers and t.v.s, are known to suppress the production of melatonin in the body, disturb circadian rhythm, and deprive the body of a precious natural antioxidant.Chronic light exposure inhibits melatonin secretion, and causes insomnia in some individuals. Even a single light bulb for a ½-hour can reduce melatonin production by 50%.
Some Vedic researchers theorize that melatonin is soma, a legendary immortality elixir believed to be secreted from the pineal gland (third eye) during meditation. A study done by Ulleval University Hospital in Oslow, Norway compared 27 meditators with 29 non-meditators, and showed that blood plasma levels of melatonin increased substantially for meditators, and declined slowly over a period of three hours.
Melatonin and light therapy are primary therapeutic adjuncts used to treat circadian rhythm disorders. Melatonin supplementation is advised by the world health organization (WHO), who named night shift work as a probable cause of cancer in 2007.Recent research has shown that eating times can also influence our circadian rhythms. In ayurveda, we use dinacharya practices to maintain and restore our circadian rhythms such as sleep hygiene, mediation, exercise, and daily cleansing.