The following excerpt is from Kundalini Yoga: The Mother Power, by Sri Chinmoy.

Purity and Kundalini 

If one opens up the chakras without purification of the vital, especially the lower vital, then one can become unbalanced, mad, insane. Many people go crazy when they open up the chakras before purification takes place. Awakening the kundalini power without first being purified is like giving a child a knife. There is every possibility of his misusing it. He may cut his finger or do something most harmful and damaging. But if one is grown up and mature, then he will use the knife to cut fruit and offer it to his friends.

Power can be utilised in two ways: either to build or to break. We have come here to build, to build the Palace of Truth and Love. Now, while building, we have to know if we are an expert architect or builder. If we are not, then the building will not be perfect and at any moment it will collapse.

So we have to know when it is advisable for us to awaken the kundalini power. When we feel that our inner vessel is pure, when it can receive Light without any obstruction, then we can easily open up the chakras without any danger. But if we arouse the kundalini untimely through our persistent desire and effort, then we may run into great difficulty.

If you wish to follow the path of kundalini, my humble advice to you is to first try to awaken the heart centre. The heart centre is considerably pure. The vital or disturbing emotions will be purified by the opening of this centre. If you can first open up the heart centre and from there take the purity and enter into the lower centres, then there is no danger.

– Sri Chinmoy