One widely held theory about the purpose of dreams is that they help you store important memories and things you’ve learned, get rid of unimportant memories, and sort through complicated thoughts and feelings.
Research shows that sleep helps store memories. If you learn new information and sleep on it, you’ll be able to recall it better than if asked to remember that information without the benefit of sleep.
How dreams affect memory storage and recall isn’t clearly understood yet. But dreams may help the brain more efficiently store important information while blocking out stimuli that could interfere with memory and learning.
What Science says about it ?
The question of whether dreams actually have a physiological, biological or psychological function has yet to be answered. But that hasn't stopped scientists from researching and speculating. There are several theories as to why we dream. One is that dreams work hand in hand with sleep to help the brain sort through everything it collects during the waking hours. Your brain is met with hundreds of thousands, if not millions of inputs each day. Some are minor sensory details like the color of a passing car, while others are far more complex, like the big presentation you're putting together for your job. During sleep, the brain works to plow through all of this information to decide what to hang on to and what to forget. Some researchers feel like dreams play a role in this process.
