The circadian rhythm, our internal clock, is the natural process that regulates the sleep-wake cycle. This has been an integral part of Chinese medicine for centuries and is being recognised in Western medicine as a fundamental aspect of health as well as an easy way to increase wellbeing. The circadian rhythm is an internal regulatory mechanism formed in all organisms in response to the environment around us and repeats roughly every 24 hours even in the absence of daily environmental signals (zeitgebergs)(1). Circadian rhythms optimise physiology and health by temporally coordinating cellular function, tissue function and behaviour. Yes every cell, organ, the whole body has a circadian rhythm that needs to stay in synch to balance health. The physiological processes known to be controlled by circadian rhythm include metabolism, hormone secretion, body temperature, cardiac functioning and ageing.(2)
In this blog post, we will delve into the understanding of circadian rhythm from the perspectives of both Chinese medicine and Western medicine, exploring the unique insights they offer on maintaining balance and harmony in our daily lives. Chrono-medicine (medicine with light) is one of the most important emerging themes in this field and provides countermeasures to circadian dysregulation.(1) There are little habits we can do with light to increase health, and tricks we can do if due to our work or lifestyle need to function outside the time of the sun.
Chinese Medicine Perspective of circadian rhythm
In Chinese medicine, the circadian rhythm is intricately connected with the flow of Qi (pronounced "chee") and the balance of Yin and Yang. According to this ancient tradition, the body's vital energy, Qi, moves through meridians in a cyclical manner, with each organ having its peak activity during specific times of the day.
The Organ clock - work with this to aid health
The Chinese organ (zangfu) clock divides the day into 12 two-hour intervals, each associated with a specific organ and its related functions. Check out this zangfu clock and examples of how the sages worked with it historically for health of the body within the environment.
3am - 5am | Lung time | Great time for early meditation and breathwork |
5am - 7am | Large intestine time | Gentle walk or movement to aid your morning bowel motion |
7am-9am | Stomach time | Great time to gently warm up your digestion with some warm water and ginger. |
9am-11am | Spleen time | This is when the body is digesting the first foods you have introduced if you are not fasting. Great time for focus. |
11am - 1pm | Heart time | Blood is in circulation, higher energy, time for social time, have your largest meal. I love social lunches with friends and family. |
1pm-3pm | Small intestine time | Time to sort and absorb food, lower energy and if you can time for a short nap. |
3-5pm | Bladder time | Energy is restored, liquid waste released, good time for work and study. |
5-7pm | Kidney time | Supper time, time to store your nutrients. |
7-9pm | Pericardium time | Protection, light reading, self love like massaging your feet. |
9-11pm | Sanjiao tripple burner time | Endocrine and metabolic balancing getting ready for sleep. |
11pm - 1am | Gallbladder time | Sleeping, cellular repair, building blood cells |
1-3am | Liver time | Deep sleep, detox Liver and Blood (often can wake at this time if you are stressed or have drunken alcohol). |
Acupuncture and Chinese medicine is a complex intervention(3). We utilise this cyclic nature of the body and give lifestyle advice such as eating, and exercising to align with the body’s natural energy flow. Understanding and being able to affect the organ clock through the movement of Qi through the body also enables us to help people recover and reset from jet lag.
Acupuncture and Chinese medicine also work on the balancing of the Yin and Yang of the body, emphasizing the balance of Yin (cool, restorative energy) and Yang (warm, active energy). Yin dominates during the night, promoting rest and rejuvenation with lower body temperatures, while the Yang phase prevails during the day, supporting activity and productivity displayed with higher body temperatures.(4) Maintaining this balance is crucial for overall health and well-being.
Western Medicine and circadian rhythm
The circadian rhythm is a temporal programme found in all organisms, coming from the millennia of the earth’s rotation, making a 24h rhythm on all processes at all levels. It is both a top-down and bottom up organisation. The cells generate daily rhythms that network to the tissues, organs and entire organism. Top-down the master conductor of this is the brain's hypothalamus, known as the suprachiasmatic nucleus (SCN). This internal clock responds to external cues, primarily light, and transduces this information to all the periphery clocks, synchronizing the body's functions with the natural day-night cycle. Without external cues our circadian rhythm could free-run and this could make cycle length of 18-30hrs.(5)
Entrainment is the process where the endogenous (internal) biological clock is reset or synchronised with exogenous (external) environmental cues. These environmental cues are called Zeitgebers. The pattern of behaviour around sleep/wake or your body clock is not a direct result of the environmental cues but they are there to make sure that the biological clock controlling behaviour doesn’t get too far out of synch with the environment. This is why we feel jet lagged when we travel, it takes a while for our biological clocks to be reset (entrained). Initially our sleep wake cycles which are determined by endogenous biological clock are out of sync with the environment but exposure to the environmental cues such as sunlight eventually helps the body to reset the biological clock.
Entrained phases (chronotypes) differ between individuals from extreme ‘larks’ to extreme ‘owls’ and most people falling somewhere between these. Factors effecting these can be lifestyle, stage of life, and environment.(1)
Things that affect circadian rhythm
Light – Morning light resets the biological rhythm. Blue light of the day represses melatonin and then this is on a timer to when you need to produce it again. When you wake up in the morning best practice is to go outside into the bright light for 10 minutes without sunglasses on. Bright blue light within 2 hours of waking increases metabolism and raises your alertness. The bright light through the window is more diffused than actually standing in the morning light and you do not receive the UV radiation for synthesising Vitamin D.(6)
Exercise – The more active day time is a better time for physical activity. Doing this at night sends your circadian rhythm the wrong messages for activity.
Food – Your body’s circadian rhythm and organs have timing. If you are eating late at night it effects your sleep, and the internal clock of your liver. Your body likes routine and prepares itself for the food arriving into your system. If you throw this out at night by eating late your body is processing food rather than slowing down for rest. As well, the readiness for the food at certain times increases digestion. A calorie taken at night is not the same on the body as one taken during the day. If you do need to snack at night have a small snack of foods high in melatonin such as pistachio’s or Goji berries.
Temperature – At night our body starts to cool into the Yin time of the evening, 2-3 hours before you wake up your temperature drops before starting to warm again for the more alert Yang time. Having a hot shower and then turning it cold in the morning will help raise your body temperature faster, and a hot shower in the evening will encourage your body to cool down to regulate.
Circadian rhythm melatonin and sleep
Melatonin is a hormone produced by the pineal gland. This plays a key role in regulating the sleep-wake cycle. In the evening as darkness falls, melatonin levels rise, signalling the body to prepare for sleep. Exposure to artificial light, especially blue light from electronic devices, can disrupt melatonin production and impact sleep quality. It is best to not have overhead lighting at night, use lamps. Have all of your lamps with a warmer hued light bulb in them. Sleep in a dark room without any electronic light sources from sleeping appliances is best.
Circadian Disruptions and Health
Western medicine acknowledges the impact of circadian disruptions on health. Studies done on mice has demonstrated that dysregulation of the circadian system leads to a multitude of pathologies.(1) Irregular sleep patterns have been linked to various conditions such as obesity, diabetes, cardiovascular disease, and mood disorders.
There can be many reasons for circadian unalignment; for many it is termed urban chronotypes (living in the city, lots of artificial light, long hours, not enough outdoors and bright light), shift workers, or lots of jet lag.
Life hacks for better sleep and balancing your circadian rhythm
Sleep in a dark room. If you are doing a night shift and sleeping during the day wear a black out eye mask.
Wake up and go outside for 10 minutes without sunglasses on and absorb some of that bright morning light. If you are working a night shift when you wake up put bright overhead light on you. Do some gentle exercise, have a cold shower.
As the sun goes down change all lighting to dimmer and a redder light, no bright light. If you watch tv or use screens at night use blue blocker glasses.
Don’t eat at night – at least 3 hours before bed. If you are working shift work don’t eat too close to when you are wanting to sleep.
There is a time delay from your waking light period to melatonin production.If you have had a bad nights sleep and you want to reset your sleeping the next night you are better to get up early and get bright light and have an afternoon nap rather than sleep in for too long.
Conclusion
It is important to realise that everyone has a varying degree of chronotype from ‘owl’ to ‘lark’, and every person may have unique circadian preferences. A personalized approach to wellness that works for you and your lifestyle is essential. But both Western and Chinese medical understanding of circadian rhythm can give you tips to add balance to your circadian cycle, giving you a personalised approach to your wellness that works with your environment and tinana (body).
The body likes routine and to synch this around your circadian clock is very beneficial to your health and wellbeing. It has been shown that an imbalance of your internal clock within itself, or to the environment increases co-morbidities. It is time to rebalance your calendar to suit your body’s needs. Honour the energy within your body, fostering a harmonious and sustainable approach to well-being.
References
1. Roenneberg T, Merrow M. The circadian clock and human health. Institute of Medical Psychology, 2016, 4(11)
2. Kondratova AA, Kondratov RV. Circadian clock and patholgoy of the ageing brain. Nature reveiws Neuroscience, 2012, Vol. 13. 325-335.
3. Paterson C, Britten N, Acupuncture as a Complex Intervention: A Holistic Model. The Journal of Alternative and Complementary Medicine, 2004, Vol. 10, pp. 791-801.
4. Refinetti R. The circadian rhythm of body temperature. Front Biosci (Landmark Ed), January 1, 2010,15:564-594.
5. Aschoff J. A survey on biological rhythms. New York : Biological rhytms (Handbook of Behavioural Neurobiology), Vol. 4. 3-10.
6. Ticleanu C. Impacts of home light on on human health. Lighting Research & Technology, 2021;53.