Think about it, you sleep in the dark, when you close your eyes to sleep, all you can see is darkness in your eyelids. This means that darkness has the potential to be everywhere, even in our favorite locations. There is always a dark place, a dark park, a dark alley, a dark road somewhere in the world, and sometimes, even in our dreams.
If you have a dream about a dark place then this can and usually is a very bad dream with dark undertones. The term dark place is usually used to refer to that area of a person that is inaccessible and contains their innermost terrible thoughts and all of their hatred and sadness. This is a term that is used by psychologists and psychiatrists to help people make sense of their son or daughter's strange fixation on going deep into themselves and dredging up all of the strongly negative emotions that make them seem like different people all together. If you have a dream in which you go to your dark place or in which you are in a dark place it means that you have been severely emotionally wounded and you are in the angry stage of your grieving. There is not much that can be done about this, you just need to come out when you are ready to feel good again.