Kundalini

"Kundalini (Sanskrit "coiled one"), in the concept of Dharma, refers to a form of primal energy (or shakti) said to be located at the base of the spine. Different spiritual traditions teach methods of "awakening" kundalini for the purpose of reaching spiritual enlightenment and supernormal powers. Kundalini has been described as a highly creative intelligence which dwarfs our own. Kundalini awakening therefore requires surrender; it is not an energy which can be manipulated by the ego." - wikipedia

"Kundalini may unravel and arise from the base of the spine (or sometimes from the feet) due to spiritual practices, or in response to life events, and when this happens it may move gradually, uncoiling like a snake, or quickly and explosively, into the gut, the heart or the head.  This event can be startling and chaotic, frightening or blissful, and it usually triggers months and years of new sensations and changes in the person who awakens it.  It may feel like the body’s wiring has moved from 110 to 220, and it takes time to adapt to it...

Kundalini awakening offers a profound opportunity for those called to follow a spiritual path.  It gradually releases many patterns, conditions and delusions of the separate self.  It can be threatening to the ego-structure because a person may feel a loss of interest in their old life and identity, and consciousness may go into unfamiliar expansive or empty states that are disorienting.  It also makes people who are unfamiliar with it afraid they are ill or losing their minds. So understanding is important..." - Bonnie Greenwell

http://www.kundaliniguide.com/what-is-kundalini/

"Spontaneous kundalini awakening can occur after something harsh has taken place in your life, something very traumatic, examples would be, death of a loved one, severe injury, having sex with someone whose kundalini is awakened, shock or even using drugs.
Fundamentally anything that postpones the logical mind and allowing the natural energy to arise can cause a kundalini awakening. The unexpected onslaught of energy allows considerable amount of adrenaline to be dumped into the system, which can cause havoc. There are many risks including insanity...One thing we can be sure about is when the kundalini is awakened, the life we know will never be the same again...
Your unconscious thoughts can be brought forward as conscious thoughts. Nothing will be buried, whether you want to deal with it or not. It will be out there..." - spiritualunite.com