We wear watches to help us keep track of time. We hang up clocks in the office and at home for the same reason. People tell me they look at their smartphones for the time, but that rarely works for me. In most cases when I pull out my phone intending to check the time, I end up being distracted by notifications and when I’ve returned my phone to my pocket or my bag, I realise I still don’t know what time it is. Maybe that’s just me. In any case, we are surrounded by objects that measure and record time for us, so that we don’t have to. But we could do it, if we had to. That’s what our circadian clock is for.
We’re all born with a circadian clock, an internal biochemical mechanism that operates in regular cycles, naturally alerting our bodies when to wake up, when to eat and when to go to bed. You may have heard of the hormone melatonin, which is produced naturally in the body but also sold in pharmacies as a way to combat jet-lag and regulate sleep patterns. Melatonin is created in the pineal gland, in the brain, and is at its highest levels at night, which is why some people call it the “sleep hormone”. You might also know that at night your core body temperature drops slightly, as part of your body’s way of telling you it’s time for bed. These physiological changes are controlled by your circadian clock, whose rhythms are baked into our genetic material.
A Harvard research paper published in 1999 showed that our circadian clocks naturally follow a cycle of approximately 24 hours, whether or not we receive external stimuli or information like daylight. Researchers placed human subjects in rooms with a constant level of low light and observed them. Over time, it was observed that even without any conscious awareness of the day-night cycle taking place outdoors, the bodies of the study participants underwent hormone production and temperature changes in a manner consistent with the 24-hour day. This happened even when researchers simulated 28-hour days through artificial lighting and programmed activities. Despite experiencing a 28-hour sleep-wake cycle, participants continued to exhibit hormonal and body temperature fluctuations in 24-hour cycles.
This is all very fascinating on a biological and neurological level, but on an emotional level, what this tells us is that we were made for this world. Even if the world ended tomorrow and we were somehow able to escape in some sort of interplanetary Noah’s Ark to establish a new colony on Mars, our bodies would still signal our terrestrial belonging. Just like the mechanical oscillator in a watch movement, which is calibrated to measure time in units that only make sense on Earth, our circadian clock is a biochemical oscillator that keeps us in sync with the planet we were born on.
We all have that friend who has a preternatural sense of time, who can tell you what time it is without looking at a watch or even glancing out of the window. I’m no expert on neurobiology, but my current working theory is that these are people who are highly in tune with their bodies, who understand what their bodies are telling them, who lead well-adjusted and balanced lives. Cortisol, otherwise known as the stress hormone, is also linked to the circadian clock, which goes a long way towards explaining why stressed people forget mealtimes and have problems sleeping.
Those of us who love watches do so for various reasons — we’re attracted to their creativity, their complexity, their beauty. But maybe on a deeper level, we love timepieces because we recognise a common chronometric kinship.
