DREAMS are a widespread subject in Judaism. First of all, the Torah is telling us about different people having dreams. The most famous examples are Yosef (the son of Yaakov) as well as Paraoh. Moreover, the Talmud (Tractate Berachot) dedicates a whole chapter on dreams and their results. Just to give you an insight: In Berachot 55a teaches Rabbi Chisda:
"A positive dream is not destined to be fulfilled in its entirety, nor is a negative dream destined to be fulfilled in its entirety".
Meaning that many different elements influence our dreams. For instance, thoughts sticking in our minds and anything subconscious. Therefore, not everything you dream is a 100% true.
Further Rabbi Chisda teaches:
"A negative dream is better than a positive dream".
"A negative dream is much more advantageous for us. At least in some ways, as it makes us think and eventually do Teshuva".
In the same Gemara (rabbinic discussion) Rabbi Berechyah teaches:
"A dream referring to a future event, even though part of it may be fulfilled, all of it will not come true".
On what exactly based Rabbi Berechya his statement ?
On one of Yoseph's dreams. When Yoseph dreamt that his eleven brothers as well as his parents would bow down to him. When Yoseph had this dream, his mother Rachel had already died years before. Thus we learn that our dreams are being influenced by other elements wandering around in our minds.