To a child, a week can sometimes seem like an eternity, particularly when it’s the last week of school before the glorious summer vacation begins. The older we get, however, the faster time seems to pass us by, until eventually it can seem like a month is over before it’s even started. There are a number of theories that might explain why time seems to speed up as we age, but first it’s important to understand that it’s all in our heads.

Time is constant

Time passes at exactly the same rate for every single human being on Earth. But for humans that aren’t on Earth, for example those who have spent time aboard the International Space Station (ISS), things are a little different. Einstein’s theory of special relativity suggests that for every six months someone spends aboard the ISS, usually an astronaut or a cosmonaut, the individual lags behind people on Earth by a whopping 0.005 seconds. While this does technically mean that people who visit space have a slightly different experience of time compared to the rest of us, it’s not exactly a meaningful difference.

They did the math

One explanation for the time-speeding-up phenomenon has to do primarily with mathematics. “The reason we feel it goes faster as we get older is simply because a unit of time becomes an increasingly smaller percentage of life as more is added to it,” explains Merriam Saunders, a Licensed Marriage and Family Therapist, children’s author, and adjunct professor at Dominican University. “So, for example, when you are 2 years old, a year represents 50% of your entire life; when you are 10 years old, it represents 10%. But when you are 50 years old, it only represents 2% and at age 80 it is only 1.25% — so infinitesimal that it whips by in a flash.” This is similar to the way many of us think about delivery charges. Paying a $3 delivery charge on something cheap, like a small box of batteries, might seem ludicrous, but paying the same fee on something expensive, like a new computer, is an absolute bargain. Even though it’s the exact same amount of money in both cases, the charge seems a lot smaller when compared to something much more expensive.

Time flies when you’re distracted

Saunders suggests another factor could be at play, which has to do with the well-known saying, “Time flies when you’re having fun.” She believes there is a bit more at play here. “The psychology behind that saying is valid, but pertains mostly to being distracted, not necessarily only to having fun. The part of the brain that is responsible for executive functioning — the prefrontal cortex — manages our ability to organize, plan, control impulses, remember things we recently heard/learned, pay attention; in other words, everything our brain needs to accomplish tasks. It also manages our understanding of the passage of time and the concept of lengths of time. So, it is likely that as we get older, we are far more distracted with the business of our lives than we were as youths with far less to juggle in that part of the brain. These distractions could account for time seeming to pass more quickly as adults.” It appears our brains become far too preoccupied with adult responsibilities to worry about trivialities like the steady forward passage of time.

Clock zooming through cyberspace
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Experiences are only new once

Yet another theory revolves around the idea that our brains use new experiences as a way of gauging how quickly time is passing by. Dr. Craig April, Ph.D., is a licensed psychologist and director of The April Center for Anxiety Attack Management in Los Angeles. As he puts it, “One major theory states that as we grow older we’re having fewer unique and original experiences. Our lives become more routine and days can blend into the next. This tends to reinforce the experience that time is moving more quickly.”

Dr. April continues, “Additionally, once you’re aware there are more days behind you than in front of you, time also seems to move more quickly based on awareness of one’s own mortality. When we’re younger, we look forward to lots of new, exciting experiences planned in the near future. And they can’t come fast enough.” He gives an example to clarify his point. “For instance, a planned trip to Disneyland, for any kid, seems to take forever to arrive. Even if it’s just one long month. This creates the experience of time moving more slowly. However, when we’re older, there are fewer and fewer of these unique, exciting experiences to look forward to. This can contribute to a feeling time is moving faster.”

A more recent theory

Dr. Adrian Bejan, the J.A. Jones Professor of Mechanical Engineering at Duke, published a paper in the journal European Review detailing his thoughts on the matter. As he writes in his paper, Dr. Bejan believes the time-slowing phenomenon is related to the fact that “the rate at which changes in mental images are perceived decreases with age.” In other words, we experience life like a movie, a continuous series of mental images. Children’s brains are able to process these mental images quicker than adults, and are therefore able to process more mental images per second. As we get older, our neural networks become more complex, which means signals take longer to travel to separate parts of the brain. Because of this, adults process fewer mental images per second, so the older we are when an experience happens, the faster it seems to have gone by in our memory.

Let’s slow it down

Having time move faster as we get older is pretty undesirable for most people, even if it is just an illusion. After all, the faster we age, the faster we reach our eventual demise, and most people would like to put that off for as long as possible. Understanding why we experience this sensation could help us develop strategies to feel like time is moving a bit more slowly. For example, if we try more new things as adults, we will have more experiences to look forward to and be excited about, which will make time seem to move slower. We can also ensure we get enough rest. Although this may seem counterintuitive, because time definitely seems to move faster when we’re asleep, it means our well-rested brains will process mental images more quickly.

Other factors

Our perception of time isn’t just related to age. For example, time seems to slow down significantly for people who are in a state of fear, probably because the increased arousal in fearful situations has an effect on our internal clock system. Body temperature can also have an effect, with perception of time increasing when body temperatures are raised, and decreasing when temperatures are lowered. On a smaller scale, we can have experiences such as the stopped clock illusion. You’ve likely experienced this illusion yourself, where you’ve glanced at a clock during a particularly boring meeting and the second hand appeared to pause for just a little too long before ticking over. This strange sensation happens because when you look at something, your brain automatically tries to fill in what was happening just before you looked. Your brain, shrewd though it may be, refuses to even consider the absurd notion that the clock was ticking the way all clocks do, one second at a time. It tricks you into thinking the second hand has lingered for just a little bit too long, by making you think it was somewhere it wasn’t before you looked. I only wish my brain would be courteous enough to play these tricks when I’m doing something I actually enjoy.