Creativity usually thrives when emotions are felt at a level of high intensity. Times of fear, anger, sadness, joy, disgust and surprise are the general categories of emotions whose energy can be focused into creativity. Some people are able to harness the energy from these times and release it in various positive forms such as poems, story telling, dance, athletics, debate, business planning, cooking, fine arts, etc… When I am feeling down in dumps I immediately start exercising alot, I use this to kick my mood up a notch. When I am filled with excessive energy, I tend to write more, draw more, my imagination tends to run wild with creative thoughts. Some folks are able to harness sad energy to create art, it acts as almost a form of therapy for them. This creative energy, no matter if it is born from a dark place or a place of light, can be focused in a positive way.
There is also the possibility of a counterbalance at play. This counterbalance can be considered a negative effect to the positive release of creative energy. I consider this counterbalance to be any self destructive behavior (there are too many to list and they are different for everyone). This counterbalance can also overtake the positive creative energy or even replace it.
I believe it is a common misconception that depressive emotions can be the cause of a lack of creativity, but instead I feel that complacency is when the mind is at its least creative state. The lack of feeling real emotions, whether positive or negative robs the mind of its creative energy. Autopilot is the death of an interesting ride.
Moderation is a fatal thing. nothing succeeds like excess– Oscar Wilde