Know Your Biological Clock: Circadian Rhythm, Homeostat And Ayurvedic Body Clock
Have you ever wondered why you feel sleepy at certain times of the day or why you don’t even need an alarm clock to wake up in the morning?
Our sleep homeostat and circadian system regulate when we sleep and how long it takes us to fall asleep.
These two internal systems interact to regulate when we sleep and when we are awake. The sleep/wake homeostat monitors our need for sleep based on how long we have been awake, while the circadian system regulates a range of functions, including when we sleep and wake every day.
The pineal gland is a small, cone-shaped pea-sized structure located at the brain’s center. It produces the hormone melatonin. The pineal gland regulates sleep and wake cycles, allowing us to know when it’s time to fall asleep and when it’s time to be awake. And thus, it acts as a biological clock in humans.
One of the most important regulators in your body is the sleep/wake homeostat. This system regulates when we feel sleepy and when we feel awake. By being aware of this system and how it works, you can find more time to sleep and less time to be disturbed during sleep by an alarm clock.
Jet lag and shift work are two of the most common times when our sleep/wake cycle gets out of sync with our biological clock, causing sleepiness and fatigue instead of alertness and energy. Exposure to light late at night or during the day can throw off the timing of our circadian rhythm and make adhering to a consistent wake/sleep schedule more challenging.
It’s no surprise that both circadian and homeostatic systems control sleep and wakefulness. These two systems usually counterbalance each other. However, because they operate independently, they can become misaligned. For instance, during jet lag or shift work, we might experience an alerting signal when trying to sleep or, conversely, a powerful drive to sleep when we need to be awake.
Biological clocks are fundamental to the functioning of life and the organization and coordination of behavior.
They are found in most organisms (including humans) and regulate various functions, such as sleep patterns and reproduction.
Some biological clocks operate on a 24-hour cycle (circadian clocks); others are tuned to the circalunar rhythm, which repeats roughly once a month with the full moon and new moon at their peaks; some tell time by the number of hours since dawn or dusk.
Your sleep-wake homeostat and circadian sleep control systems work together to control when you go to sleep and wake up. The clock in your brain determines what time of day it is, affecting the homeostat. If you’ve been awake for a long time and the clock reads later in the day or evening, you’ll probably feel fatigued because it’s probably getting close to bedtime. When you get sleepy (based on how long you’ve been awake), signals from your body help keep you asleep so that your rest is adequate.
Many biological rhythms are set by external cues that change daily: light and dark, food availability, temperature fluctuations, and social interactions with other animals. These environmental oscillators synchronize internal clocks in response to a fixed set of cues. Thus, when you get up in the morning, your circadian clock automatically gets reset so that you go through your daily tasks without becoming disoriented.
Here, we review historical evidence for biological clocks in plants and animals, examine their structure at the molecular, cellular, and systems levels, and explore how they work to control biological processes. We also consider whether they can adapt to environmental changes and stressors such as temperature fluctuations or light/dark shift cycles (jet lag) and determine why they display such robust oscillations in some species but not others. We will explore potential future applications based on chronobiology, including time-of-day specific cancer treatments or memory training programs that use night shifts or bright lights to manipulate timing mechanisms of brain function.
Early research was critical in understanding structure-function relationships in the central nervous system. Indeed, identifying the pineal gland as a “master pacemaker” conveyed a sense that it hierarchically organized the system. However, as the properties of the pineal gland’s function became more evident, the identification of new pacemakers in the hypothalamus and retinae made the system appear more complex. The findings lead to a better understanding of how multiple inputs contribute to daily rhythmicity in wakefulness and sleep and how altered physiological states (such as aging) contribute to circadian disorganization, such as insomnia.
The molecular and physiological mechanisms by which circadian clocks regulate the timing of physiological processes and behavior remain unknown. The recent identification of fundamental oscillatory properties in the central pacemaker implies that these oscillations are coupled to peripheral tissues, presumably via sympathetic/parasympathetic diurnal rhythms. It opens exciting new avenues for investigating the mechanisms by which circadian systems transmit effector signals at appropriate times.
The latest research reveals that biological clocks are an opportunity to track and help understand aging. It allows investigating the differences in individuals’ biological versus chronological age and shows environmental factors influencing biological aging rates.
The corrections that could help maintain the normal biological clock can be better done by accepting the ayurvedic practices mentioned based on the normal physiological functioning of the human body.
- 3 am-5 am — lungs; self-cleaning; deep sleep ends.
- 5 am-7 am — large intestine; Do all cleansing activities such as Defecation, Yoga, Walking, exercise, kriyas, etc. if defecation is not done, water is withdrawn, and stool becomes hard to pass(constipation). Drink 1 liter of water.
- 7 am-9 am — stomach — have breakfast (largest meal) containing all the nutrients.
- 9 am-11 am — Spleen & pancreas; high alertness; meeting; exams; intensive mental activities. Do work.
- 11 am-1 pm — heart; pumps nutrients to the body received by the lunch, lightly socialize.
- 1 pm-3 pm — small intestine; completes digestion and absorption of food ingested earlier
- 3 pm-5 pm — bladder — work, study, tea break
- 5 pm-7 pm — kidneys — liquid detox takes place, Dinner; exercise can be done, restore energy
- 7 pm-9 pm — heart — socialize; intimacy
- 9 pm — 11 pm — triple burner — another accessory organ system — create equilibrium through the endocrine system and assist sleep.
- 11 pm-1 am –Gall Bladder
- 1 am -3 am — liver is most active. It is used to detox the day’s toxin accumulation in the entire body. If this time isn’t given, then toxin accumulation becomes very high. If late sleeping becomes a regular habit, then several diseases develop. It won’t help by sleeping during the day; one continues to feel tired, do less work, and the body gets weaker.
Body Clock according to Ayurveda
- According to Ayurvedic medicine science, in the morning hours, before and after sunrise, one should wake up and ease into the day calmly and slowly. In the first two hours, as the Kapha element is a predominant and sharpest rise in blood pressure, melatonin secretion stops at around 7:30 am, bowel movement is likely to occur, and the highest testosterone secretion at 9 am.
- One should eat the largest meal of the day at around 10 am, and as the pitta element dominates in the later hours of the day, facilitating the easy and complete digestion of the heavy meal, it is the time for high alertness.
- Mid-noon is the time of greatest productivity- work or exercise and best coordination.
- Post-noon, at around 2 pm, one feels most alert and creative. Good time for tackling problems, designing, or constructing projects as this hour of the day is highly dominated by vaata; that is to say, it is the fastest reaction time with the highest cardiovascular efficiency and muscle strength at 5 pm. Most elevated blood pressure again at around 6:30 pm.
- Post sunset, there is a surge of Kapha again; hence the ideal thing is to get to bed before 10 pm, peacefully falling asleep as the melatonin secretion starts and bowel movement is suppressed.
- Mid-night is the time reserved for organ healing and restoration and is not ideal for any activity or food.
- Late night, at 2 am, is an essential time for active dreaming. The brain can express creativity, and the body can physically be at rest and almost undisturbed with the lowest body temperature.
Dr Shuchitha is an Ayurveda Physician, Researcher and Yoga Practitioner with a Master’s in Pharmacology and PG Diploma in Clinical research. She has a modern mindset with a desi tadka. She is a passionate dancer, singer and an impromptu writer. She calls herself the scribbler of poems. She is a vintage soul who enjoys music, art and nature, loves capturing it’s vibrancy.
