Each November, as we shift our clocks back to standard time, we are answering the body’s subtle call to fall into rhythm. The early sunsets and cool dark mornings nudge us toward the seasonal slowing of our ancestors, as we more closely align ourselves with the cycle of the sun. And yet this transition can often leave us feeling groggy, moody or otherwise “off”.
These sensations are not imagined. They are rooted in a highly sensitive time-keeping system orchestrating daily rhythms in nearly every organ of the body. The circadian rhythm is a fascinating process, described by scientists as
internal daily fluctuations in physical, mental, and behavioural activity that can synchronize with the earth’s rotation1
Our bodies are intricately wired to align with the rise and fall of the sun. When this happens – when our internal clock and our social clocks are aligned – we feel rested and energized. When we fall out of sync, the body loses it’s natural cadence. And that’s when imbalance begins to take root.
This system plays an important role in metabolic, mental and hormonal health and can be used to help influence our well-being. Understanding the factors that support circadian health is easier than you might think.
The Biology of Time
This internal timekeeping is regulated by a variety of CLOCK genes, with the master clock living deep in brain tissue in the hypothalamus, sending out commands like an Army General to local clocks throughout the body. In fact, astonishingly, roughly 80% of all genes that encode proteins (genes) appear to be regulated by this mechanism.2 Which means that this system is crucially important to how we function.
Even more crucial are knowing what disrupts this delicate balance. Environmental influencers are known as Zeitbergers, or “time-givers” and are part of an interplay between our genes and our environment, which can be used to our advantage in supporting health.
The Master Clock (SCN)
- Located in the hypothalamus and receives light from photo-receptive cells in the retina
- “Tells time” based on cues of light and dark3
- Morning light, higher in blue light, raises cortisol production. This stimulates alertness, prepares the body digestion and coordinates hormones
- Evening light, higher in red and orange light, stimulates melatonin production
- Synchronizes local clocks in body organs and tissues
Peripheral Clocks
- Found in organs such as the liver, GI tract, heart, pancreas, immune system and reproductive organs
- Disrupted by Zeitbergers such as exercise, meals and social cues
- Mismatches between our master and peripheral clocks can impair blood glucose regulation, increase inflammation, alter lipid metabolism and weaken our cellular function
Consequences of disruption
Did you know that in the days following daylight savings time, rates of heart attacks, strokes, car accidents and mood disturbances rise? Our return to syncing with the sun in the fall shows a similar fall in these effects, illuminating the importance of aligning ourselves with nature.
Modern life, too, contributes to the blurring of our social, circadian and the solar clock. We keep late hours with artificial light, eat quickly and at varying hours and play “catch-up” a few days a week to try and reset.
These disruptions affect nearly every system in our body.
Metabolic and hormonal disruption
When circadian rhythms are disrupted, metabolic changes begin quickly. In a controlled study of healthy adults, just three days of misalignment lead to “significantly elevated fasting glucose and free fatty acids”4. Elevated morning blood glucose can be one of the earliest signs of circadian stress.
Hormone rhythms depend heavily on circadian integrity. When these rhythms shift, metabolic stability declines.
- Cortisol (stimulated by daylight) follows a steep morning rise and gradual decline
- Melatonin peaks at night (stimulated by fall in cortisol, darkness)
- Ghrelin and leptin – the hunger hormones – follow predicable daily cycles
- Insulin sensitivity is higher earlier in the day (another reason to avoid late night snacks)
- Liver enzymes that metabolize medications follow circadian rhythms and can alter medication effectiveness
Stress, Mood and Cognitive disruption
Clock genes influence our sleep-wake cycles, emotional regulation, and cognitive functions like learning and memory. Emerging research in Alzhemier’s disease supports that disruption in our circadian cycle can affect the ability to clear toxic waste from our brain, contributing to Alzheimer’s pathology5.
Disruption can lead to:
- Increased anxiety
- Lower stress resilience (measured by HRV)
- Altered mood
- Impaired cognitive performance
- Increased risk of depressive symptoms
Circadian Health in the Modern World
While we cannot always control our schedules, we can support our circadian alignment with small. meaningful shifts. These practices are simple, but they have a profound impact on our health.
- Get morning light within 30 to 60 minutes of waking. Aim for at least 5-10 minutes
- Get evening light to stimulate melatonin
- Eat during daylight hours, avoiding late night meals.
- Exercise at consistent times each day
- Dim lights at night and use warmer bulbs or lamps
- Use blue light blockers or minimize screens after sunset
- Keep sleep wake times consistent – even on weekends
- Get outside time every day, in every weather (bundle up!)
- Develop a consistent bedtime routine
Functional Medicine and Rhythms
From a functional medicine perspective, circadian health is one of the clearest examples of how lifestyle can influence gene expression in real life. Choices made every day such a light exposure, food timing, movement and rest are sending signals which support, or disrupt, our biological clock.
When circadian rhythms are aligned, the body is more efficient, resilient and adaptable.
Supporting rhythm is one of the simplest and most powerful ways to support root cause healing.
To learn more about Functional Medicine and see how it may help you, schedule a free 15 minute consultation or head to the Work With Me page! Don’t forget to sign up for our newsletter below as we delve into topics like lifestyle medicine, ingredient highlights, medication concerns and more.
Anytime that you are experiencing a health concern, please contact a healthcare professional for guidance. In the meantime, ensuring that you are providing your body with the nutrients it needs and supporting it through sleep and stress reduction will always provide benefit. The content on this site is for informational or educational purposes only and does not substitute professional medical advice or consultations with healthcare professionals.
References
National Center for Biotechnology Information. (2024). Circadian rhythm, epigenetics and disease interaction (PMC11800305). U.S. National Library of Medicine. https://pmc.ncbi.nlm.nih.gov/articles/PMC11800305/
- Pilorz, V., et al. (2021). The role of clock genes in sleep, stress and memory. Biochimica et Biophysica Acta (BBA) – Molecular Basis of Disease, 1867(6), 166184. https://www.sciencedirect.com/science/article/pii/S0006295221000897
- Genetic Science Learning Center. (2016) The Time of Our Lives. https.//learn.genetics.utah.edu/content/basics/clockgenes
- National Institute of General Medical Sciences. (n.d.). Circadian rhythms [Fact sheet]. https://www.nigms.nih.gov/education/fact-sheets/Pages/circadian-rhythms.aspx
- Roenneberg, T., & Merrow, M. (2019). Genetics of the human circadian clock and sleep homeostat. Neuropsychopharmacology, 44(1), 186–201. https://www.nature.com/articles/s41386-019-0476-7
- National Center for Biotechnology Information. (2024). Circadian disruption, clock genes, and metabolic health (PMC11245155). U.S. National Library of Medicine. https://pmc.ncbi.nlm.nih.gov/articles/PMC11245155/
- National Center for Biotechnology Information. (2024). Circadian disruption, clock genes, and metabolic health (PMC11245155). U.S. National Library of Medicine. https://pmc.ncbi.nlm.nih.gov/articles/PMC11245155/
- ScienceAlert. (2023, September 12). Alzheimer’s may hijack your cells’ clocks, hinting at new treatments. https://www.sciencealert.com/alzheimers-may-hijack-your-cells-clocks-hinting-at-new-treatments
- American Academy of Sleep Medicine. (2020). Permanent standard time is the optimal choice for health and safety: An American Academy of Sleep Medicine position statement. Journal of Clinical Sleep Medicine, 16(10), 1789–1795. https://doi.org/10.5664/jcsm.10898