In Kabbalah we learn that a dream can contain one sixtieth of prophecy.
Meaning that sometimes in your dreams there are visions of the future or guidance offered to you from the spiritual realm.
The issue with this is first getting to a place where this type of prophecy is contained in your dreams and second being able to understand that portion of your dream is a prophecy and interpret it properly.
For the most part your dreams are a collection of thoughts that you are internally preoccupied with during the day or things in your subconscious mind.
Your dreams can also be a physical response to something you ate during the day or any intense emotions or stress you felt throughout the day.
However, if you are able to go to sleep with a calm mind clear from thoughts, and without any distracting physical responses to food you have eaten or drunk, then it is possible that you could receive a prophetic vision in your sleep.
Further, you may even ask G-d before you go to sleep to communicate with you in your dreams or to answer a question in your dreams.
We know of one person who did this before they went to sleep and they had a dream in which they saw and spoke to both of their parents, who they were very close to when they were alive but were both now deceased).
This person woke up with such a calm and positive feeling about his life and was so happy to have had the chance to see his parents again.
Usually when you have a dream it is very hard to know whether this is just random thoughts or is there a meaning behind it, a higher power trying to tell you something,
According to Kabbalah one of the basic tenets in dream interpretation is to always interpret your dream in a positive way because it is written that the dream follows its interpretation.
Meaning a dream will be what you make of it. Therefore even if a person has a dream that sounds terrible; there are drowning or they are falling etc.. you have to be creative and try to interpret it positively; that you will soon be consumed and drowning in love; that you need to let something bad in your life fall off so you can get to a higher place.
You have to look at every dream to try and interpret for your good.
If you have a nightmare and no matter how much you try to interpret it for the good you still feel unsettled about it, then the Kabbalah says that you should give charity.
Charity will nullify the effects of a bad dream.
So there are things you can do about bad dreams and there are ways to understand dreams that you feel are prophetic.