You know those memories you determine to hold in your mind? Time has other plans. Your brain is too efficient, and it strips out all the details of life's events until all that is left is the emotional response you felt at that moment. You remember the event the way you remember a dream—almost as a outsider to your own life. My distant past is barely reality. My first love is but a mere idea. My childhood is only as real as the sepia-tone photos that document it.
Scientists have determined that adrenaline is the chemical that acts as a catalyst for binding long-lasting memories in your mind. The moments when one experiences increased adrenaline are usually "fight or flight" moments. The details that bring you into these survival mode moments are locked into memory as a defensive mechanism. I think this concept applies to dreams as well.
Most people don't remember their dreams after waking up. But those dramatic dreams—the ones where you fall off the roof or keep tripping in front of the steamroller rolling your way—those are the ones that stick. I think your body's adrenaline kicks in and causes those dreams to be locked in your mind. What do you think?
Memory recall in the 21st century is disappointing overall. I would like to offload memories like an external hard drive, dismissing the painful ones until I can deal with them. Nothing as extreme as "Eternal Sunshine of the Spotless Mind," but rather something to keep me from forgetting important mile markers in my life! I'd like to revisit some of them as a surprise too.