But for the first time scientists have shown that LSD really does wake up the mind, sparking connections in areas of the brain which do not usually communicate.
In a controversial study led by Imperial College, the brains of 20 volunteers were scanned while they were high on acid.
The astonishing images show that virtually every part of the brain is active during a trip, allowing users to experience a dreamlike state of vision normally only found while asleep.
The drug appears to break down barriers which usually separate areas of the brain from each other, allowing vision, movement and hearing to blur together, stimulating ideas that probably could not happen in a normal state.
The researchers say it may be the reason why many LSD users report religious or spiritual feelings of “connectedness.”