Most dreaming takes place during the REM phase of sleep. In this time, brain wave activity becomes similar to waking brain activity. And studies, including one reported by the International Business Times, have shown that there could be a direct link between the amount of brain wave activity in the temporoparietal junction (an area of your brain which processes emotions and information, amongst other things) and how well people remember dreams. Increased activity in this area of the brain could put people into a state closer to wakefulness whilst still asleep, allowing the brain to better encode and re-member dreams. But it could be much simpler than that.
Whilst you sleep, many of the processes which allow you to create long term memories lie dormant. For example, the production of an important neurotransmitter, norepinephrine, which helps you to form memories, slows down while you sleep, only existing at very low levels during the night. As we wake up, our brains start to turn on the processes needed for long-term memory storage. This means that if you wake up directly out of a dream then you have a much higher chance of remembering it.
Extremely vivid and emotional dreams, such as nightmares, are much more likely to wake us up, as they stimulate the brain and body more intensely. Vivid dreams are more likely to be experienced by people going through grief, stress, or trauma, or by people with mental health conditions such as depression, anxiety or PTSD. Even things like an alarm clock which wake you up suddenly from REM sleep can make dream recall more likely. So, whether or not you remember your dreams could simply be a result of when and how you wake up. This also explains why dream recall sometimes varies from day to day for the same person. And this, in turn, could be influenced by factors in your life and your character.
It is possible to use techniques to increase dream recall. Anything that distracts you immediately after waking can stop you from remembering dreams, as your brain may not have had enough time to form long term memories. One of the best ways to improve dream recall is to note down any dreams that you can remember immediately when you wake up, before your memory has been disrupted or forgotten. You could also set an alarm to wake yourself up roughly five hours after you have gone to sleep (this is when you are most likely to be in REM sleep). At this point, you are most likely to remember your dreams. The world of dreams is a mysterious one, and the scientific research is still developing. But, whatever the reasons, when you go to sleep tonight you might be well on the way to an amazing scientific or creative discovery! Sleep well…