used. Sometimes the relaxation, which is experienced in a hammock, can be improved, by putting on a headlamp and following the light spot on a ceiling with the eyes. In this way the head and the light spot generate an axis — like a pendulum. These two senses, the sense of gravity and the sense of seeing, experience something same. So one sense is the feedback-sense for the other and feedback can be frequently a great help for becoming healthy. This exercise has a lot in common with the …