Such experiences are more common than some would like to think. And though they are not fully understood there is more known about them than some would like to think.

Related phenomena are near death experiences and autoscopy (and doppelgaenger phenomena).

Usually, the subjectively perceived position of the "I" is within the body (mostly above the waist though no necessarily inside the head). Under some conditions (lack of oxygen, medication, meditation, some states of sleep, neural stimuation, brain tumor, extremely high arousal etc...)the body scheme of the brain breaks down and the "I" s perceived subjectively to be outside of the onfines of the body.

The way I can induced that perception in me would be extreme sleep deprivation.

By itself, it is not unhealthy or dangerous but it may accompany otherwise dangerous states (near death, e.g., by definition).

Susan Blackmore is a researcher who has experienced this phenomenon herself (if I recall corrrectly under the influence of marihuana) and has written a lot about it from the POV of a brain researcher.

A lot of reasearch is also done in Switzerland. One link to an article is

Out-of-body experience and autoscopy of neurological origin .

Peter Brugger too (also from Switzerland) has often published on such things.

No serious researcher ever has ever scoffed such experiences BTW. Only sometimes some of those who have had such experiences do not like to hear other explanations than those they have made up themselves to explain what has happened to them.

Wolfgang