Often lots of people's third eye are not open because they are blocked. The third eye is a sixth chakra but connected to the first, second and third chakra's and blockages in this lower chakra's will also cause a blockage in the sixth. Oftentimes, the cause of blockages are fear and disbelief, though Tibetans and Indian yogis believe third eye is blocked for past life karma . Some people refuse to believe that they are blessed with a sixth sense while others are anxious of the images they might see once they have opened theirs.
Yoga nidra or yogi sleep has been used for thousands of years by yogis. In the Upanishads, there are three states of consciousness: waking, dreaming and deep sleep. Yoga nidra allows an individual to leave the waking state, move past the dreaming state and into deep sleep while remaining awake or conscious during the whole process. In yoga nidra, there are no dreams to explore. Instead, it is a process of emptying. It purifies the deeper aspect of the human mind by exploring deep impressions or samskaras. This is essential as samskaras drive our karma.