system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are our dreams so easily forgotten?

I often feel that I have the most vivid and elaborate dreams but as soon as I wake up, my recollection of the dream is completely wiped from memory as if it never happened. What accounts for this strange phenomena?
gpt
The ability to remember dreams changes from person to person although studies have shown that more than 95% of us are like you and completely forget our dreams.
Basically we have short term memory and long term memory. Dreams are a sort of stream of consciousness that pass rapidly through your short term memory and you won't remember it unless it's passed into your long term memory as soon as you wake up.

Nothing has been 100% proven but among the most plausible reasons put up by scientists are:

* Neuro-chemicals in our brain are different when we are asleep and when we are awake. For whatever reason, they block dreams from your memory. Dreams help us process unconscious information absorbed throughout the day. It's possible that the brain understands it's all a bit gibberish and decides for us that it's not necessary to remember it.

* You can't "purposely try to remember" dreams while asleep so you're not passing the dream information into your long-term memory.. It's the same for people who sleep walk.. they walk around, cook food, cross roads.. but pass none of the information into their long term memory to "remember" later.

That being said, there *ARE* some things that you can do to help you remember your dreams. Research has shown that the biggest difference between people who remember their dreams better than others is just that they are more interested in dreams in general, or place more importance on the significance of dreams.
People with poor dream memory are a lot less likely to be good at tasks that involve their visual cortex (eg. they are shown a picture of a fruit bowl and are then given the fruit and asked to arrange it all in the same order as in the picture they were shown)

If you keep a notepad and pen next to your bed, and write down what you remember of your dream as soon as you wake up, you are, in part, training your brain to remember dreams (because you are placing importance on them and in writing it down, passing it to long term memory) and bit by bit your brain should adapt and start to better remember your dreams! (As best it can anyway, given the potentially nasty neuro-chemicals that are trying to make you forget ;p)

HTH
(EDIT for formatting)