Henri

It can be very helpful to dive, say two weeks a year, in a course or teaching you`re really interested in. These two weeks will give you enough energy for the rest of the year and will be a real start for your personal development.

It can help with certain illnesses, but limited. You can even reach samadhi with certain type of drugs but it won`t last long. There`s always a chance that it will harm your nervous-system and that`s too much of a danger. In the end self-developing is about independance and freedom so I would suggest to get rid of it.

A good book on this topic; The marriage between sense and soul bij Ken Wilber.