As I write this the clocks have gone back and we are passing over the threshold of winter… now each day is a step closer to the time of the longest night on December 21. It is a remarkable thing when you think about it, to live at a latitude where the balance between light and darkness varies so greatly across the seasons. And indeed the mystery of this phenomenon, particularly the long hours of dark winter, play as an overture to the millennia of myth and legend on this island. It was in these times of darkness and quiet, that myth and mystery were spun together to summon ancestors and the unseen. The time of Samhain when the veil was thin, a time which is still so resonant with us.
As I imagine into this, I picture an intimate and cosy darkness lit by candles and firelight and people gathered round spinning tales. An idealised image granted, but it strikes me how at odds this image is with our modern lives. The advent of electricity dispelled the visiting ghosts from the shadows and with it much of our sense of mystery. Our “ghosts” have been ejected and in their place came screens: first the flickering glow of television sets, themselves relics of a previous age, and now the irresistibly shiny virtual brightness of our digital devices.
Those long dark winter nights, which offered a time of rest, quiet reflection and connection have been replaced by relentless brightness and stimulation. The darkness remains, but our relationship with it has changed. Rather than entering into it, we resist it.
Yet our bodies have not forgotten the ancient dance between light and dark. And while my last article was an invitation to embrace the darkness of the long nights, we are creatures of homeostasis and our biology seeks equilibrium. In the shorter winter hours of natural light, it becomes vital to increase our time spent outdoors in nature. It is important to remember that adequate exposure to natural daylight helps regulate the body’s circadian rhythms and supports the production of melatonin in the evening. Without sufficient exposure to daylight, these rhythms can become disrupted, making it harder to fall asleep and maintain healthy sleep patterns.
Indeed, the change in the clocks, whether it is falling back or springing forward can lead to an increase in depressive symptoms in the days after the clock change due to the adjustment in our exposure to light. Interestingly, daylight saving as an official policy only came about during World War 1, as a wartime measure to conserve energy. It has fallen in and out of favour over the years for various reasons but at present over 70 countries still apply it despite growing health criticisms.
Light and darkness seem inseparable in our biology. We need darkness for rest, repair, and renewal, just as we need light to regulate countless processes throughout the body. It is this subtle yet profound relationship with natural cycles and rhythms that anchors us in ourselves, connecting us to a deeper sense of time, place, and belonging.
Natural daylight contains UV (ultraviolet) rays for vitamin D synthesis, blue and visible light for circadian rhythm regulation as well as red/near-infrared wavelengths. The bright intensity of midday light, particularly its strong blue-light component, provides one of the most powerful signals for synchronising the body’s internal clock and regulating hormone production. In this context, a simple lunchtime walk becomes something more than exercise; light itself becomes a source of nourishment for our biological processes.
Emerging research suggests that our relationship with sunlight reaches much deeper into our physiology than previously imagined.
A landmark study published in 2020 by Cincinatti Children’s Hospital, aimed to investigate how mice could maintain body their temperature in cold conditions. What scientists uncovered over the course of this research was a previously unknown pathway linking light, fat metabolism and energy balance. Their research found protein receptors in our subcutaneous fat cells deep under our skin which can sense and respond to light. These receptors in our fat cells detect violet and blue light, invisible to the human eye, which can penetrate clothing and skin to activate the receptors, influencing how brown and white fat cells work together to regulate energy metabolism.
The findings raise intriguing questions about the biological consequences of modern indoor lifestyles, where exposure to the full spectrum of natural sunlight is often greatly reduced. It is also worth noting that prolonged exposure to artificial light, particularly blue-enriched light from screens and LED lighting during the evening, can disrupt the body’s natural circadian rhythms. This may suppress melatonin production, interfere with metabolic regulation, and contribute to poorer sleep quality, with potential downstream effects on health.
As we enter the season of darkening hours, we are reminded of our need for light and of how profoundly our evolution as a species has depended upon it. We may have imagined that our technological advances could somehow free us from this dependency, allowing us to overcome the limits imposed by the rising and setting of the sun. Yet the reality is far more complex than we once understood.
We are wired for light. Deep within our ancient and sophisticated biology are systems that respond to the rhythms of day and night, reminding us that we are not separate from nature’s cycles. For the sake of our health and wellbeing, we are programmed to move in step with them, participating in a dance that has shaped life for millennia. Darkness too offers its own essential gifts. As I mentioned in my last article, darkness and sleep brings the body respite, where it can be restored, repaired and renewed.
At this Samhain time, I wish for you the equilibrium of darkness and light; the ancient rhythm that carries us through the turning of the year. On the threshold of winter, may you find space for rest and ease, remembering that we are wired for both the light that sustains us and the darkness that restores us.
