Why Summer Feels Shorter Every Year

It's Monday, June first. Summer starts in three weeks, and if you're over twenty five, you already know how this goes. You'll blink and it'll be August. You'll blink again and someone will be talking about Halloween costumes. By December you'll say "I can't believe this year went so fast," the same thing you said last December and the December before that, and you'll mean it every time. When you were a kid, summer lasted forever. A single afternoon at the pool felt like it had its own time zone. Now entire months disappear without leaving a trace. You're not imagining this. It's a measurable psychological phenomenon, and the explanation involves math, memory, and the uncomfortable possibility that your brain is editing out most of your life because it's decided you've already seen it. The simplest explanation was proposed by a French philosopher named Paul Janet (zhah-NAY) in 1897, and it's the kind of idea that's either brilliant or depressing depending on your mood. When you're five years old, a single year is twenty percent of your entire life. That's enormous. A summer is roughly five percent of everything you've ever experienced. Of course it feels infinite. You're living inside a huge fraction of your total existence. By the time you're fifty, a year is two percent of your life. A summer is half a percent. The same three months that once represented a significant chunk of everything you'd ever known now register as a rounding error. This is called proportional theory, and the math is clean but relentless. Your tenth birthday to your eleventh birthday is ten percent of your life. Your fortieth to your forty first is 2.5 percent. Each year is objectively the same length, but subjectively, relative to everything that came before, it shrinks. The twenties feel faster than the teens. The thirties vanish faster than the twenties. And everyone over fifty reports the same thing: decades feel like they used to feel like years. The good news is that proportional theory probably isn't the whole story. A 2025 study tested it directly and found that it explains some of the effect but not all of it. Which means there's something else going on, and that something else is actually more interesting because, unlike the math, you can do something about it. William James, the psychologist who showed up in our emotions episode arguing that you're sad because you cry rather than the other way around, wrote about this in 1890. "The same space of time seems shorter as we grow older," he observed, and his explanation was about memory. The more distinct memories you form during a period of time, the longer that period feels in retrospect. The fewer memories you form, the shorter it feels. This is why childhood summers felt endless. Everything was a first. First time at camp. First time staying up past midnight. First crush. First time getting hurt badly enough to remember it. First time being somewhere without your parents. Each of those experiences was novel, and your brain encoded novel experiences in extraordinary detail, building dense, vivid memory structures that took up a lot of mental real estate. When you looked back on a summer that contained thirty distinct, richly encoded memories, it felt vast. Your brain had a lot of footage to review. Now think about last June. What did you do? Can you name five specific things? Most adults can't, because most of adult life is routine, and the brain handles routine by compressing it. If you drove the same route to work two hundred days in a row, your brain didn't store two hundred separate memories of that drive. It stored one template and applied it to all of them. The individual days collapsed into each other. Same thing with meals you've had a dozen times, meetings that blur together, evenings spent scrolling on the couch. Your brain is efficient. It doesn't waste storage on information it's already cataloged. The problem is that this efficiency makes your life feel shorter, because when you look back, the compressed sections barely register. Months that contained no novel experiences get filed as if they barely happened. Neuroscientists describe this in terms of "temporal landmarks," the small disruptions to routine that give your brain something worth tagging. A vacation creates temporal landmarks. A new job does. Moving to a new city does. Learning a skill does. Anything that forces your brain to pay attention and encode new information stretches your subjective experience of time. Without those landmarks, weeks and months slide by in a blur, and when you look back, there's nothing to grab onto. There's also a physical component to this that's slightly unsettling. Adrian Bejan (beh-ZHAHN), a mechanical engineering professor at Duke, proposed in 2019 that the brain's processing speed literally slows as you age. As neural networks grow larger and more complex, electrical signals have to travel farther, which means you process fewer "frames per second" of visual and sensory information. A child's brain is capturing more snapshots per unit of time than an adult's brain. More frames means more perceived time. Fewer frames means time feels like it's moving faster. Your brain is running the same movie at a lower frame rate, and the result feels like fast-forwarding through your own life. The practical implication of all this is that the feeling of time accelerating isn't inevitable. It's a side effect of how you're living, and it can be reversed, at least partially, by changing what you expose your brain to. Travel is the most reliable time-expander. A week in a country you've never visited will feel longer in retrospect than a month at home, because every day of the trip is packed with novel sensory input: new streets, new food, new language, new customs. Your brain is encoding at maximum density the whole time. This is why people come back from a two-week vacation and feel like they've been gone for months. They have, in terms of their brain's recording. But you don't have to buy a plane ticket. Novelty is the variable, and novelty can be local. A new running route. A cooking class. A conversation with someone outside your usual circle. Driving a different way to work. Any break from autopilot forces the brain to pay attention, and attention is what creates the temporal landmarks that make time feel real. The research also suggests that mindfulness and present-moment awareness slow time perception in real time, not just retrospectively. When you're fully absorbed in what you're doing, time feels like it's passing at its actual pace rather than skipping ahead. Boredom, weirdly, might also help. Kids experience time more slowly in part because they feel boredom more intensely. Adults have learned to fill every idle moment with a phone screen, which eliminates boredom but also eliminates the stretchy, elastic quality of unstructured time. I think about this heading into summer because summer is the season that reveals the gap between how time worked when we were kids and how it works now. When you were ten, summer was an ocean. When you're thirty five, it's a puddle. The length didn't change. Your brain's relationship to novelty did. The encouraging part is that you can hack the system. Not with productivity tricks or time management apps, but by doing things you haven't done before, even small ones, and giving your brain something worth remembering. The summer will still be three months. Whether it feels like three months or three weeks depends almost entirely on what you fill it with. So if this comes up in conversation, here's how to think about it. Time feels faster as you age for two reasons. First, each year becomes a smaller fraction of your total life, so it registers as proportionally less significant. But the bigger factor is that your brain compresses routine experiences and only records novel ones in detail. Childhood summers felt infinite because everything was new and your brain was encoding at maximum density. Adult summers disappear because most days look like the days before them. The fix is novelty: new experiences, new places, new skills, anything that forces your brain out of autopilot and gives it something worth tagging as a distinct memory. Summer starts in three weeks. Make it a long one. Stay informed, stay curious, and we'll see you tomorrow.