In the book Empires of Time: Calendars, Clocks, and Cultures, sociologist Anthony Aveni summarizes some of the factors that affect people's subjective sense of time. The brain's Intuitive system includes several internal "clocks" that use signals from the environment to regulate our behavior. For example, we use temperature signals to regulate our daily sleep-wake cycles; think about how well you sleep under the covers in a cold room, versus under a thin sheet on a hot summer night. Another kind of external signal is provided by the sun: Morning light triggers a cortisol surge in the adrenal gland, which produces alertness and focus but also stresses the body. If you have ever pulled an all-nighter or crossed several time zones on a flight, you know that the worst part is the time just before local dawn when the body desperately wants sleep. If you push through that part, you will gradually start to feel better when external cues like daylight cause the the normal daily (circadian) rhythm to reassert itself. Environmental factors like light and temperature are called zeitgebers (German: "time-givers") because they serve as controllers to set or regulate our internal clocks.
Besides circadian rhythms, humans are also sensitive to longer-term (ultradian) cycles like those of the sun and the moon. In the springtime when days grow longer, many people experience improved mood and more energy to accomplish tasks -- a particularly useful tendency in agrarian societies when there is more work to be done. Autumn brings a tendency for lower activity levels, which in modern societies contributes to seasonal affective disorder but in agrarian ones is useful for conserving energy at times when food reserves are dwindling. Lunar-cycle examples are harder to find in humans, although there are hypotheses related to reproductive activity (for primitive societies, this is better timed during the dark part of the month than at full moon, when added daylight hours could be used for hunting instead). A much stronger example of lunar influence is seen in the behavior of oysters transplanted from New Haven CT to Chicago IL; even when kept in a closed environment, these mollusks can sense lunar gravitation and modify their daily open-close cycles to match the tides of a nonexistent ocean in the middle of the great plains. Like many Intuitive-level factors, humans' sensitivity to environmental factors leads to effects that can be quite strong, but that are often outside our awareness.
Besides a strong sensitivity to factors such as light, temperature, and the time of the year, humans also possess an internal clock that regulates our behavior separate from any external cues. This clock is found in the suprachiasmic nucleus of the brain, and produces wakefulness and fatigue by regulating the production of hormones (e.g., melatonin produced by the brain's pineal gland). The internal sleep-wake cycle lasts slightly longer than 24 hours, so that when a person is isolated from external cues they tend to wake at a gradually later time each day. In normal circumstances this tendency for the internal clock to run longer than a day is offset by the body's sensitivity to external cues: Like the way our calendar adjusts to the solar cycle by periodically adding leap days or even leap seconds, the body adjusts its internal rhythm to the external cycles of days, months, and years. In older people the electrical activity of the suprachiasmic nucleus decreases, contributing to sleep disturbances; the brain therefore may become more dependent on external cues to stay regulated as people age.
The sensation of being "out of sync" with natural rhythms is a disconcerting one. Jet lag, for instance, is not just a state of fatigue due to sleep deprivation. It makes you feel much more bone-tired because it involves a disconnect between your body's internal clock and the timekeeping cues from your environment. Similarly, people who are chronically stressed experience a kind of "burnout" in the adrenal gland so that they no longer get a morning surge of cortisol -- instead, the hormone stays at a relatively constant level throughout the day. This contributes to feelings of fatigue and depression, and predicts worse longer-term health. Finally, most countries consider it a form of torture to keep people in an environment with constant light and/or in uncomfortable positions that prevent normal sleep. Sensitivity to external cues normally helps to keep us regulated, but when our internal clock is too far off from our environment the experience of being out of sync can be a painful one.
To keep our internal and external clocks aligned, societies throughout history have developed complex timekeeping mechanisms. The image at the top of this page shows how specific celestial events at different times of the year line up precisely with specific positions of the dolmens and menhirs at Stonehenge. The primary modern theory about Stonehenge is that it was designed for this purpose, so that ceremonial activities could take place at specific times that were tied to astronomical observation. Dr. Aveni's book traces the similar timekeeping mechanisms of other ancient civilizations, such as the orientation of the Mayan city of Uxmal which aligns buildings with the positions of the sun at specific times of the year (solstices and equinoxes), as well as the movement of the planet Venus around the sky. The Inca aligned monuments in different parts of their widespread empire so that they would match not the local time, but the solar apex and zenith in their capital city -- a kind of "Cuzco standard time." And in North America, the itinerant Lakota people used the positions of constellations to tell them when to gather together at specific geographic locations such as Black Elk Peak, the Stone Prairie (Pe Sla) in the Black Hills, and the Bear Lodge (Devil's Tower, WY) where they would perform the Sun Dance ceremony. These ceremonial activities are often viewed by modern people as superstitious, religious, or perhaps even mystical in nature. But they likely also served a practical purpose, which was to synchronize people's internal clocks to the larger rhythms of nature.
Coming back to our collective "out-of-time" experience in 2020, it seems likely that we are lacking basic cues to help our internal clocks track to the seasonal rhythms. Modern humans have less direct connection to the activities of planting or harvest, and therefore the days and seasons themselves are less useful as cues. We instead tend to rely on ceremonial time, although instead of druids celebrating the solstice at Stonehenge we look to the start of football season or the end of summer vacation as our key indicators of time. When these types of ceremonial cues were disrupted by the pandemic, we had fewer anchors to correct our free-running internal clocks. Even on the daily level, the absence of a commute or a clear start and end to the workday may leave us feeling adrift in time.
Collectively, then, we are experiencing a kind of societal jet-lag as our Intuitive time sense drifts further from the social rhythms that help it stay aligned with the days, months, and seasons. It's a subtle but potentially meaningful consequence of the pandemic that can leave us feeling vaguely out-of-sorts, and like many aspects of the Intuitive system this phenomenon can affect our moods, our energy level, our sleep, and our behavior without us completely knowing the reason why.
Comments
Post a Comment