What the data actually shows
Surveys and everyday reports consistently find that people, especially older adults, feel that time passes faster than it used to — the experience itself is well documented even if its cause is not. So the starting point is solid: this is a real and common perception, not an illusion only a few people have.
One long-standing explanation is the proportional theory, often traced to the psychologist William James, who noted that as we age each unit of time becomes a smaller share of our total experience. To a 5-year-old, a year is a fifth of their whole life; to a 50-year-old it is a fiftieth. The same calendar year therefore feels proportionally smaller and so seems to pass more quickly. It is an elegant idea, though it is more a reframing than a measured mechanism.
A second strand emphasises novelty, attention and memory. Neuroscientists who study time perception, including David Eagleman, have argued that we judge elapsed time partly by how much detail a period left behind. Novel, rich experiences are encoded densely and feel longer when we look back; routine, predictable stretches are encoded sparsely and seem to evaporate. Because adult life tends to become more routine, more of it gets compressed in memory — which can make whole years feel like they slipped by.
Why this feels different from how it actually is
Part of why the effect is so convincing is that it draws on memory, which we mistake for a clock. We do not actually measure how long a year took; we infer it from how much we can recall happening. A year full of first experiences feels long because it left a thick trail of memories, while a year of repeated routine feels thin and short — even though both contained exactly 365 days.
Childhood, by this account, feels expansive largely because almost everything in it is new. The first day of school, the first time somewhere, the first of countless ordinary things all register vividly. As adulthood settles into familiar patterns, fewer experiences cross the threshold of being memorable, so the same span leaves less behind and reads as shorter when we look back.
The proportional idea adds a second layer: even setting memory aside, your internal sense of 'how big a year is' shrinks as your accumulated life grows. So two distinct effects can stack — a year is both a smaller fraction of your past and likely to be encoded with less novelty — which is why the sense of acceleration can feel so strong rather than subtle.
What the research says to do about it
If the novelty-and-memory account is even partly right, it suggests a gentle, low-stakes response: deliberately introducing new experiences tends to make a period feel fuller in retrospect. Travel, learning something unfamiliar, changing routines, or simply taking a different route can lay down denser memories, which is the mechanism the theory links to time feeling slower. This is offered as a plausible inference, not a proven prescription.
Paying closer attention to ordinary moments may have a similar effect. Because routine partly works by letting experiences pass without being encoded, attending more fully to everyday things can help them register as memories rather than disappear — which is consistent with how mindfulness is often discussed in relation to time perception, though the evidence here is suggestive rather than definitive.
It can also simply help to know that the feeling is normal and shared. The acceleration of time with age is one of the most commonly reported experiences there is, and understanding the leading explanations tends to make it feel less like something is being lost and more like a predictable feature of how memory and proportion work.
What the research says does not help
Treating the feeling as a sign that you are wasting your life usually does more harm than good. The acceleration is widely reported across people living very different lives, which points to general features of perception and memory rather than to any personal failing. Reading it as a verdict on how you spend your time misattributes a near-universal experience.
Frantically cramming activities in to 'slow time down' tends not to deliver, because the effect linked to slower-feeling time is novelty and attention, not sheer volume. A packed but repetitive schedule can leave just as thin a memory trail as an empty one; doing more of the same is not the same as doing something new.
It is also worth resisting confident, single-cause explanations. Popular accounts sometimes present one mechanism — proportion, or a specific brain process — as the settled answer. The honest state of the research is that several explanations are plausible and partly supported, and none has been shown to be the complete story.
Real numbers in context
There is no clean number for how much faster time 'really' feels, because the experience is subjective and the explanations are not fully settled. What the field does offer are two leading, partly supported accounts. The proportional theory associated with William James frames it arithmetically: at 5 years old a year is a fifth of your life; at 50 it is a fiftieth — so the same year is a far smaller fraction of your accumulated experience and feels correspondingly smaller.
The novelty-and-memory account, associated with researchers on time perception such as David Eagleman, frames it in terms of how densely a period is encoded: novel experiences leave richer memories and feel longer in retrospect, while routine ones leave little and feel short. Both are best treated as plausible explanations rather than proven mechanisms — the underlying feeling is well documented, but its precise cause remains an open question.