Etymology: Zeitgeber literally translates from German as “time giver.” The term was coined in the late 1950s by physician Jürgen Aschoff, a pioneer in the study of biological rhythms, or chronobiology. Aschoff established that humans and animals synchronize their circadian rhythms, meaning the cycles that command the body’s internal clock, to the Earth’s rotation. According to his research, our notion of time and the way our bodies adapt to it respond to zeitgebers—environmental time cues—such as sunlight or feeding cycles. In an experiment that lasted over two decades, from 1964 to 1989, Aschoff tested how volunteers responded to being cut off from those zeitgebers when isolated in a bunker for weeks at a time. His conclusion: Devoid of time cues, humans no longer had an internal clock and each individual developed zeitgebers of their own. 

In her 2023 book, Saving Time: Discovering a Life Beyond the Clock, artist Jenny Odell proposes a new, 21st-century take on the word. Our notion of time, she argues, is malleable and expands or shrinks following zeitgebers that can be as varied as a mother’s breastfeeding cycle, an assistant organizing their time according to their boss’s preferences or a Twitter user’s ever-updating news feed. 

Meaning:“Are you still watching?” Most Netflix subscribers will know—and dread—what this question implies. Namely, the realization that it’s already been 90 minutes (roughly three episodes) since the moment they started watching a series on the platform. As hours dilute into a dopamine-filled storyline, a streaming-induced zeitgeber can take the form of how many episodes one can binge-watch at a time.

How we experience the passage of time is subjective, but so is the way our bodies and our brains adapt to it. Odell believes that capitalism and modern technologies can shape our perception of time just like dark-light cycles do. For instance, she says, she noticed how Twitter’s nonstop notifications accelerated her own relationship to time passing. Living at the pace of outrage-fueled tweets and breaking news affected her interest in events that developed more slowly or “less sensationally,” like the local effects of climate change, or even what happened in her friends’ lives, she writes in The New York Times. 

The same goes for someone who is accustomed to constant communication from their employer, or who has to wake up before dawn to commute to work. Through these artificial cues, our brains can be entrained into cycles that continue to influence our lives’ patterns even after the original zeitgeber is gone. Odell was able to opt out of social media and readjust to a calmer life offline, but she warns against the lasting impact of modern society’s frantic pace on our body clocks. While it’s not always possible to do away with those external factors, awareness of what shapes our time allows us to slow down and focus on what really matters: our loved ones, our immediate environment and being in the moment.