If time is nothing but change, then the body is our personal benchmark for tracing it. We know when puberty is likely to arrive, when our metabolic rate will dip and when our ability to reproduce will stop. We even know when our natural life will likely to end. But beyond providing useful milestones, our bodies also directly impact how we experience time. Here’s how bodily rhythms and states enable us to feel time.
Right now, a whole network of clockwork mechanisms are at work inside you regulating your breathing, blood pressure, pulse, hormone release, digestion, cell division, alertness, metabolism and temperature – to name a few. Each has an individual cycle or rhythm, which often follows a peculiar periodicity, working almost like clockwork.
These biological clocks are found in virtually everything that lives. They are regularly repeated functions and behaviours that keep us alive and pace the rate at which we age. Some operate on a yearly cycle, some on a lunar month, and others on a daily cycle. Circadian 24-hour rhythms actually appear to be hardcoded into our cells. Plants will continue to unfold their leaves and honeybees will continue to feed at set times of day even when an external clue like light is removed.
But our external environment can still influence them. External cues like light, temperature and redox cycles can all adjust them. So we can make plants flower and bear fruit out of season in winter just by subjecting them to artificial light and temperature control. We ourselves can change our sleep/wake cycles by timed exposure to light or by going to bed a certain number of hours later every day. Crucially, it is the Earth’s particular rotation that has impressed a 24-hour regularity onto the genes of most living creatures.
Interestingly, our social designs for time best demonstrate our felt biological time. Take our master body clock, for example – the sleep-wake cycle. Busy work and social schedules, stress and travel all disorient it, causing huge fluctuations in the quality and patterns of our sleep.
We each have a biologically determined preference (a chronotype) for sleep and activity, making us either a late or early riser. Social schedules like school and work can considerably interfere with these, so that people with later chronotypes build up substantial sleep deficits by the end of the week and use free days to compensate for it. It’s a phenomenon scientists like to call “social jetlag” – the gap created between our biological clocks and the external clocks that rule our lives.
The social practice of daylight saving has a similar negative effect. Winding clocks forward in spring has been linked to an increase in accidental deaths and injuries – notably road traffic accidents. And clock changes in general have been tied to everything from elevated risk of heart attacks and strokes, to an increase in suicide attempts and psychiatric admissions.
Information from our bodies can also can help us situate ourselves in time. Changes in bodily states and sensations may function as timekeepers, warping our perception of duration:
“The perception of the bodily signals is really essential for our feeling of the passage of time. This is clearly seen in all these states when you’re feeling hungry, thirsty or even pain.” – Marc Wittmann
Take body temperature, for example – temperature fluctuations due to illness can cause our experience of time to speed up or slow down. So, the higher our body temperature, the longer a minute seems to last; and the lower our temperature, the shorter it feels.
Then there are environmental factors which induce changes in our physiology. Experiments show that people’s sense of duration becomes strongly impaired over several days when they are deprived of sensory stimuli, like sound, touch and visual cues – in most cases reporting time to pass painfully slowly.
Of course, what we actually take into our body can also affect how we experience time. LSD, mescaline, and cannabis can all produce states of altered consciousness, making time race for some, stand still or even reverse for others. Caffeine, cocaine and amphetamines actually speed up some of our bodily activities to make time intervals seem longer. Depending on what you take, you have a very different experience of yourself and of time.
So what we feel and how it makes us respond to the world around us is largely formed by information origination within our bodies. Since that information is individually felt, nobody’s time is quite the same.