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Many people feel that life speeds up as they get older. But what actually causes this sensation? A new study published in Personality and Social Psychology Bulletin sheds light on the reasons people perceive past periods of their lives as having passed quickly. Across four studies, researchers found that the feeling that time has flown by is more strongly associated with personal growth, satisfaction, and nostalgia than with daily routines or a lack of meaningful experiences.
Across cultures and age groups, people consistently report that time seems to pass faster as they grow older. This perception isn’t just a curiosity—it can influence life satisfaction, existential anxiety, and engagement with long-term goals. Despite its impact, the underlying psychological mechanisms remain poorly understood.
Historically, a common explanation is the routine-compression theory: when life is filled with repetitive tasks and few novel events, people form fewer unique memories. In retrospect, the time feels empty or collapsed, and thus shorter. An alternative hypothesis, based on self-determination theory, suggests that when people feel they did not experience personal growth, they judge the time as wasted and brief.
The researchers behind the new study sought to evaluate both theories and explore new possibilities. They wondered whether the perception that time flew by might actually be driven by how satisfied people felt with that period—and whether nostalgia could also play a role.
Across four studies involving nearly 2,500 participants in total, the researchers used surveys to examine how people recalled different time periods—such as the past year, a college semester, or the summer. They assessed participants’ memories of how routine or varied the period was, how much personal growth they felt they experienced, how many events stood out, and how satisfying or nostalgic the period felt.
In the first two studies, participants included university students reflecting on an academic year and a broader adult sample recruited online reflecting on their past year. In the final two studies, the team gathered responses from another online adult sample and from a new group of college students, this time reflecting on the past summer.
Participants responded to questions on a range of topics. These included how repetitive their days felt, how much they grew in terms of autonomy and competence, how many events they could recall, how satisfied they were with the period, and how nostalgic they felt about it. They also rated how fast that period felt in hindsight using slider scales.
The traditional routine-compression account received weak support. In two of the four studies, people who remembered a period as more routine also felt it had passed more quickly. But routine did not consistently predict how many events participants remembered. And even when it did, fewer events were not linked to slower time perception—in fact, sometimes the opposite was true.
The self-determination-based growth-deprivation hypothesis also did not hold up. Rather than feeling that time flew when they lacked growth, participants were more likely to say time sped by during periods when they did feel they were growing. This unexpected pattern led the researchers to reconsider their framework.
They proposed two new explanations. One was the growth-immersion account. According to this view, people feel that time passed quickly when they were deeply immersed in meaningful, challenging activities that supported their personal development. The satisfaction that came from those activities might have made them less aware of the passage of time—similar to how people lose track of time during a “flow” state.
The second was the growth-longing account. Here, the idea is that looking back on a time of growth may trigger a sense of nostalgic longing. The period might feel special and emotionally significant, but also fleeting, because it stands out as a high point in one’s personal development.
To test these new ideas, the researchers looked at whether feelings of satisfaction and nostalgia explained the link between remembered growth and time perception. Across two pre-registered studies, they found that both satisfaction and nostalgia predicted faster perceived time passage. And when these factors were included in statistical models, the direct effect of growth on perceived speed disappeared. This suggests that growth may influence time perception indirectly, by increasing satisfaction and nostalgia.
Between the two new explanations, satisfaction appeared to be a slightly stronger predictor of how fast time seemed to pass. Still, both played significant roles.
The studies relied on self-reports and cross-sectional data, which means they can’t definitively establish causation. It’s also possible that people who generally feel more nostalgic or satisfied with life are more likely to perceive time as passing quickly, regardless of actual events. Future research could use longitudinal or experimental methods to better understand how growth, satisfaction, and nostalgia shape time perception.
Age and lifestyle may also moderate how routine or growth is experienced. The routine-compression effect was more evident in older, more demographically diverse samples than in younger college students. This suggests that the meaning of “routine” may shift with age or life circumstances.
Finally, the researchers noted that people might be remembering different types of events when asked to recall memorable experiences. Their studies did not distinguish between ordinary daily events and major life milestones, which might have different effects on time perception.
The feeling that life flies by may not be a symptom of monotony or wasted time, as some theories suggest. Instead, it may reflect the opposite: periods filled with growth, satisfaction, and rich emotional meaning tend to feel shorter in hindsight. Rather than worrying that time is slipping away too fast, people might reframe that experience as a sign that the period was meaningful and well-lived.
This shift in perspective could help individuals come to terms with the pace of life and may even encourage them to seek out more self-determined, fulfilling experiences. As the authors suggest, perhaps the goal shouldn’t be to slow life down—but to make it rich enough that its swift passage feels worthwhile.
“Time appeared to pass swiftly when it followed a repetitive pattern of routine, but critically, when it also was fulfilling, evoking a sense of satisfaction and immersion, and perhaps to a lesser extent, nostalgia and longing,” the researchers concluded. “The growth-immersion and growth-longing mechanisms converge to suggest that time flies because you got a lot out of it. This conclusion points to a novel intervention to encourage people to reappraise life’s apparent acceleration as a sign of a meaningful life. In other words, perhaps the goal should not be to ‘slow life down’ at all, but rather to encourage people to interpret the feeling that a period zipped by as a sign that that period was well lived. Life goes fast, we say, but you wouldn’t want it any other way.”
The study, “Why Life Moves Fast: Exploring the Mechanisms Behind Autobiographical Time Perception,” was authored by Young-Ju Ryu, Mark J. Landau, Samuel E. Arnold, and Jamie Arndt.
