Eli5: Why, if at all, does it seem like the years go quicker as you get older?

Question

I hear a lot of people making that remark, that the years go by quicker as you get older.
For me, at least, it seems like that’s only the case if nothing much changes in my life in that year.
To me, years seem to feel like they go slower if there’s lots of new/different things happening.

In: 348

Answer 1

Because your brain compares times in terms of how much time it has been alive, a day as a kid seems like an eternity because you really only have less than 10 years to compare it to, so it looks ‘bigger’ for your brain.
When you are an adult days start to be a less significant part of your entire life and your perception of time speeds up.