I’m as guilty as the next person. The allure of just one more episode of my latest favourite TV series on streaming services as one am ticks past on my watch, or the ten more minutes in bed turning into an extra hour at the weekends and the occasional skipping of meals to make up for the jumbo-sized snack scoffed down the night before.
We’ve all done it, thinking that our bodies would correct themselves in time, but what if those naughty indulgences become habit? What if we are wrecking our bodies without even noticing?
The number of recent studies into the effects of a dysfunctional body clock stopped me short today. Published in the last six weeks alone, I found four separate studies that cite sleep-wake cycles and circadian rhythm disruption as causal links to Parkinson’s Disease (UC San Francisco Weill Institute for Neuroscientists, June 2020), asthma and allergies (European Lung Foundation, July 2020), children’s emotional control (University of Houston July 2020), and cardiovascular disease (PLOS, June2020).
And that’s just the tip of the proverbial iceberg. A little more digging and you find that our body clock is responsible for the smooth running of just about every system in our bodies, from the more obvious hormonal control to decreased cognitive function and attention deficits.
What are circadian rhythms?
In us mammals, there is a central clock sitting inside a region of the hypothalamus in the brain. It’s called the suprachiasmatic nucleus, or SCN for short. It receives signals from photoreceptive cells in our eyes that are designed to pick up on the blue wavelengths of the spectrum. That means during the morning and afternoon, the sun’s rays are filtered by our atmosphere so that much of the light reaching our eyes is in the blue region, although we hardly notice that consciously. This burst of strong light at around 480nm triggers these cells in our retinas. They fire a message up to the SCN forcing it to switch off the production of a chemical which makes us naturally drowsy, melatonin.
By the time the sun starts to set, the rays reaching us through the layers of the atmosphere are closer to the red end of the spectrum (>600nm). Over the course of thousands of years, we have adapted to pick up on these environmental cues. The special cells in the eyes are designed to almost ignore the red light, allowing the SCN to begin producing melatonin once again. This makes us more receptive to sleep.
Most of us already knew that these factors are involved in our natural sleep-wake cycles, but I was less aware of the associated chemical and neurological cascade from this suprachiasmatic nucleus. This central clock is not alone in regulating our body systems. It may receive environmental cues from sunlight and eating times, but it also sends and receives information to peripheral clocks present in other areas of the brain and in most other cell types and tissues throughout the body.
For optimal health, ALL our body clocks must be in sync.
According to Frederik N Buijs and his colleagues (2015), dysfunctional circadian rhythms are associated with diabetes, hypertension, cancer, and psychiatric disorders. Our molecular body clocks are directly influenced by the environmental cues received from the SCN. Together with a set of carefully balanced feedback loops and a number of interacting genes, this system is perfectly attuned so that the whole process takes twenty-four hours to complete, thus driving our natural circadian rhythms.
Without any natural cues such as daylight, we go on following this cycle, even if we are isolated in deep space or a bunker for long periods of time, although eventually the rhythm does begin to lengthen.
This SCN region of the hypothalamus in turn, sets the speed for other glands and organs to function optimally. The synchronisation between each system provides the feedback on temperature fluctuations, hunger cycles and hormone balances. Like most finely tuned systems, when one part is significantly disrupted, the rest of the linked rhythms are similarly knocked off course too.
The problems resulting from this are obvious. Our delicate body clocks cannot adapt quickly enough to accommodate rapid changes to modern life. What took thousands of years to evolve can no longer cope with high levels of blue light from our electronic gadgets of the last twenty years.
More and more studies are proving beyond any shadow of doubt that our natural sleep-wake cycles are significantly contributing to our declining health.
Sleep debt
The most noticeable impact is exhaustion. One or two nights of disrupted sleep can be tolerated by the average person, but when this tips over into persistent sleep issues, other symptoms can be indicative of more serious conditions.
Without the full range of sleep stages per night, from Rapid Eye Movement to deep sleep, our brains are not able to flush out the metabolic waste products accrued in tissues during waking hours. If these toxic chemicals are allowed to built up, it can result in increased inflammation and, in extreme cases, the break down of neural connections and healthy tissue.
Poor sleep leaves us groggy, with low attention spans, slow reaction rates and cognitive impairment. Put simply, lack of sleep slowly kills off our ability to function.
Mental health issues
An unsynchronised body clock has been shown in various studies to drastically increase the risks of developing mental health disorders. This includes papers on anxiety (Flo and colleagues, 2012), Bipolar disorder (Bellivier et al, 2015) and the severity of schizophrenia (Benson et al, 2015).
Publishing in the New England Journal of Medicine (2008), Belmaker and colleagues made a strong case for linking circadian rhythm disruption to Major Depressive Disorder.
The symptoms associated with MDD are typically alterations in sleep patterns, sexual desire, appetite, an inability to sense pleasure, a slowing of speech or actions, suicidal thoughts, and perpetually crying. This ailment affects huge numbers of people worldwide. The Global Burden of Disease Consortium ranked MDD in the top ten leading causes for disease in all but four of the 195 countries included on their list. They claim that the number of people diagnosed with depression increased globally by 18% during a ten-year period.
While researchers are working on definitive proof to ascertain whether the disturbance to circadian rhythms is responsible for mood disorders or the other way around, the link is indisputable. Tests on lab rodents show that artificially disrupting body clocks incites mood disorders and that resynchronising rhythms improves symptoms.
Could it be that over those ten years, our fascination for 24 hour access to electronic media has battered our body clocks to such an extent that our systems are wholly unaligned? And that’s not taking into account the jet setters who jump through time zones or those who have no option but to work shifts. Most of us have the ability to switch off our devices and alter our behaviour to achieve better sleep, but many cannot afford such a luxury.
Increased risks of hypertension and strokes
In addition to the light cues from the SCN region of the hypothalamus, critical timing regulators synchronise our bodies in ways that impact our kidneys, brain, nervous system, vasculature, and heart rhythms. Together, they send messages back and forth to regulate the speed at which everything runs, from food metabolism to heart rate.
Just as dysfunctional circadian rhythms can influence mood, it can also have a significant impact on blood pressure. Whether you are diagnosed with hypertension or not, disharmony of the body clock is associated with an increased risk of cardiovascular disease.
The evidence for this is strong enough for insurance companies to rate shift workers at greater risk of developing heart disease and strokes, thus amending their policies accordingly and charging higher premiums.
According to a new study, published in the journal, PLOS Biology, disruptions to the sleep-wake cycle exacerbates atherosclerosis (deposition of fatty plaques on blood vessel walls) and thus may increase the risk of strokes from increased inflammatory pathways.
What can we do?
I dare say within months there will be another raft of new studies linking our failure to listen to the subtle signals of our bodies and more diseases and ill health. So, what’s the solution to this most modern of ailments?
Unless we can all evolve to cope with such a change to our biological chronology, we need to restrict the amount of blue light reaching our eyes during the evenings and stick to a more regimented pattern of sleeping and eating whenever possible. Statistics show that we are hurtling into a medical maelstrom that could dwarf our recent global troubles on a gargantuan scale.
If rats and mice can reset their heart rates, blood pressure, and mood swings with chrono-therapeutic practices then perhaps we ought to start listening to the growing number of scientists in agreement. The more we shun our natural ties to the environment, the worse our health will be.
Sleep well, everyone and I wish you all good health.