The key factor to remember the dream turned out to be the theta wave which is around 4 to 7 hertz according to an Italian research team.
I know that REM is related with our dream but sometimes I didn't remember dream even while I was awoken during REM( I believe) so this research has given me a clue to resolve the question. It says we only remember our dream when there is a slow pulse that is called theta wave and the wave is also crucial to the remembering power while we are awake. I think if we want to remember something, we had better to use the time and places it happened along with the associated emotions and other contextual knowledge so the theta wave might occur on our cerebral cortex.
I am suffering a short term memory loss these days and might use this knowledge to improve my memorising skill.
