The Half-Life of Dreams

Here's something I've noticed about my recollections of dreams. The amount I seem to remember follows something like an exponential decay process. The amount of decay each time has reasonably big error bars (it could be 30% or 70%, I dunno), but the time intervals seem about right.

Immediately upon waking up instantly I've forgotten about 50% of the dream.

10 seconds after waking up, I've forgotten 50% of what I initially remembered

1 minute after waking up, I've forgotten a further 50%.

5-10 minutes after waking up, I've forgotten a further 50-70%

1 hour after waking up, I've forgotten more (the rate slows down a bit by now, but call it 50%).

By that afternoon, I've lost maybe another half (which by now gets us to about 1.5% of the original memories, which seems about right). The decay continues, so that after a week or so it's practically all gone. The number of dreams I can remember over the space of years (anything about at all from the dream) is probably about 5, and all were weirdly vivid at the time.The process can get delayed somewhat if I repeat my dream to someone soon after waking, but even then they get forgotten for good before long.

It's as if the brain knows not to junk up valuable neurons with recollections of dreams. Evolution has wrought strange mysteries indeed.