Why does time seem to go faster as we get older?

There is no single scientific consensus, but psychologists and neuroscientists have proposed a few compelling theories as to why time feels like it accelerates as we age:

• The Proportional Theory: This is a mathematical perspective. When you are five years old, one year represents 20% of your entire life. When you are 50, one year represents only 2% of your life. As we age, each unit of time becomes a smaller fraction of the total time we have lived, making it feel shorter by comparison.
• The Novelty Effect: When we are young, the world is full of "firsts"—the first day of school, the first time driving, the first job. Our brains process these new experiences deeply, creating rich, detailed memories. As we get older, our lives often fall into predictable routines. When experiences become familiar, the brain stops paying close attention to the details, which can make a month or a year feel like a blur because there are fewer unique "memory anchors."
• Biological Clock Changes: Some researchers suggest that as our metabolism and heart rate slow down over time, our internal "pacemaker" might also slow. If your internal biological rhythm slows down relative to the external world, the outside world seems to be moving faster.
• Information Processing: Studies have shown that the speed at which our brains process visual images decreases slightly as we age. When the brain processes information more slowly, it can lead to the perception that time is moving faster, similar to how a high-frame-rate camera captures more detail than one moving slowly.

In short, it appears to be a mix of how we cognitively measure our lives against the past and how our brains prioritize new information versus routine.