The feeling that one had more time in youth is an illusion. There isn’t less time. That can’t be. What’s actually happening is that the brain has more stuff. Cramming even more things to it takes longer.
Measuring time in absolute units in the context of learning is not helpful. A measure for how fast the brain could process input per unit time would be more appropriate. Yet the many kinds of inputs and variations of brain states make for even more combinations of the two. Creating a yardstick for that is hard.
Sleeping is easy in comparison. There’s nothing like good sleep to give the brain time to make space for new data. It is of interest that the exact same cause as the brain having thoughts make getting to sleep difficult.
Once one makes the intention to sleep known, it’s as if thoughts become aware of being in line to the chopping block. Each one makes their best case right then hoping to survive the upcoming purge. Hear them one by one, but do not engage. It is their way to say goodbye.
Imagine holding a sieve against the current of a river. In fact we do not have to be so fancy. Imagine fingertips touching the sand spread against the coming and going of waves. Or against running water from an open faucet.
In this metaphor, there’s supposed to be some brain, some time, some sleep, and some learning; but they all got away. Sleep and don’t waste water. Enough for today.