This is a concept believed by the worshippers of Sufism. The mystical night defines a state in which all sensory perception is blocked out in order to achieve mystical contemplation. This idea has sometimes been taken literally as for example by the Brahmin Yogis, who carefully closed off the eyes, ears, nose, and mouth to attain visionary ecstasy.
The essence of the concept is that it is necessary to shut off all physical sensory input in order that the inner or spiritual senses might operate more freely. This essentially means the shutting out of all external sense impressions such as hope, fear, consciousness of self, and every human emotion so the interior light or vision may be seen more clearly. A.G.H.
Source: 81, 297.