It's just that most people are likely to get drowsy and go to sleep. But with direction, one's mind can still maintain "focus" and high sensitivity in this state of extreme relaxation.
只不過一般人在這種放鬆狀態下很容易昏沈而進入夢鄉；若經過有意義的引導，則在放鬆當中，精神還是可以保持在「局部集中」的敏銳狀態。