Einstein’s theory of relativity is complex, but at its core, the theory expresses a truth that people grasp intuitively: time is not a universal constant, but a subjective experience. As a physicist might explain, the faster you move through space, the slower you move through time.

While time is a subjective experience, two people who have their feet planted firmly on the Earth should perceive time in the same way because they are traveling through space at the same relative speed. Yet everyone who has made it through their teens and twenties understands that, subjectively speaking, time speeds up as we age. Those endless summers in grade school give way to weeks rushing past as we labor in middle age to finish a project.

In our senior years, time moves even more rapidly. As our birthdays approach, we think to ourselves, it wasn’t that long ago that I was ten years younger. Grandchildren who seem to have been just recently born are suddenly graduating from college. The perception that time flies — and does so with increasing speed as we age — is nearly a universal phenomenon.

Time and Memory

Philosophers and psychologists have long tried to understand the subjective impression that time speeds up as we age. As a team of psychologists at Stanford University explains, our shared perception is not “a moment-to-moment sense of time acceleration that occurs with age but rather the hindsight perception that years and decades passed increasingly faster.”

The phenomenon is particularly pronounced when we look back at blocks of time. Research demonstrates that the last ten years of our life seem to have passed more quickly for older adults than for younger people. On the other hand, our perception of the speed at which the last year passed is about the same regardless of our age.

One theory suggests that subjective impressions of the passage of time are related to how we process memorable events. In childhood, we frequently have new experiences. We recall the first day we attended school, the first time we tied our shoes, our first bicycle ride. The period in which those “firsts” occurred seem longer because so much happened — that is, so many long-term memories are formed.

As we age, however, we have fewer memorable “firsts”. Even when we do something new, we’ve done something like it before. We might be middle-aged when we take our first trip to France, but if we’ve taken other trips to other countries, the experience doesn’t have the same novelty. Memories of recent experiences tend to be less vivid than those of early experiences. Our experiences become routine and routine experiences begin to flow together. Fewer events stand out in our memory. This theory posits that subjective time accelerates with age because we form fewer memories of striking events.

The Role of Cognitive Decline

A study published in 2026 questions the theory that subjective impressions of accelerating time occur because we have fewer memorable experiences as we age. The researchers “found no link between how fast people felt the last 10 years had passed and how many autobiographical (personally significant) memories they could recall from that decade.”

Compared to younger study participants, older adults described their memories as “more vivid and meaningful” than younger participants did. The researchers concluded that aging does not cause us to “lose richness of experience; we may even savor it more.” Dr. Marc Wittmann, a psychologist who participated in the study, writes:

In a way, it’s a quiet reminder to embrace the moment—carpe diem—and growing older doesn’t dull our memories; it deepens them. What an unexpected and genuinely encouraging twist in our study.

So what is the actual cause of the universal sense that time moves faster as we age? The psychologists who conducted the study tie that perception to a gradual cognitive decline that begins in our 30s and becomes more pronounced in our 50s.

The study found that the sense of time passing more quickly was strongest in older study participants who scored poorly on tests that required them to recall spoken words after some time had passed. The researchers hypothesized that as we age, our ability to encode new memories deteriorates. Dr. Wittmann writes:

When fewer everyday events can be encoded in detail, the memory “density” of a decade thins out. Looking back, that sparse record makes the years feel compressed.

This theory differs from previous understandings of the phenomenon because it rejects the theory that our ability to make meaningful memories — the ones that stand out as special — is diminished as we age. In the researchers’ view, older adults still form “special” memories that are as rich as those we make during our younger years. It is our declining ability to recall a large volume of less significant events that links memory to the (seemingly) faster movement of time.

The Good News

While it may be discomfiting to understand the subjective acceleration of time as a function of declining cognitive abilities, Dr. Wittmann suggests that we have some control over that decline. The perception that time moves more quickly is probably inevitable, but older adults can take steps to protect against cognitive decline and thus make their perception of time slow down.

Physical activity (including regular exercise) is a safeguard against deteriorating cognitive abilities. Other safeguards include mental stimulation and social connections that keep us emotionally engaged. “In other words,” Dr. Wittmann reports, “living well with people we enjoy may help to both keep our minds sharp and o