How to Sleep - page 1
When you sleep, at first, you must stand with your back to the side of a bed, bend your knees slowly and put your buttocks on the bed. At such times, the imaginary line drawn vertically from the end of the buttocks that is the coccyx must cross a point on the bed at least 25 cm away from the edge. If possible, you should sit down deeply enough so that not only your buttocks but also some portion of the rear side of your thighs will rest on the bed. Due to the fact that ther e usually is sleeping equipment such as a mattress, a sheet and a blanket on the bed, generally unfixed (except for the case when two persons try to lie down simultaneously from both sides of a bed), the action of putting one's buttocks on the edge of a bed makes the upper half of the individual's body extremely unstable. Especially seeing as a mattress is a product whose value is argued or decided upon almost entirely by its elasticity, it is easily compressed by the weight of the upper half of the indiv idual's body, inducing a sudden sinking of its surface, and, moreover, augmenting the already sharp inclination of slippery cloth products such as a sheet or a blanket.
This inclination, augmented at the edge of the bed, may throw the person down to the floor, the strength of the impact the human body receiving from the fall proportional to the height of the bed. Namely, if the height of the bed is less than 30 cm above the floor, though there are differences among individuals, the impact is attenuated by the elasticity of the buttocks themselves, injury to the human body can usually be avoided. If the height of the bed is approximately 50 cm, then bilateral ischii lying at the lowermost part of the pelvis receive a mild impact; and if you fall from the height of 1 m, the impact upon the coccyx and the pubic symphysis is transferred to the spine and you experience some difficulties in standing and walking for several minutes. If the height of the bed is 2 m, the pelvis is seriously injured: the impact travels along the spinal cord and reaches the brain,bringing temporary anopsia, dyspnea, dysarthria, or deafness. Likewise, the seriousness of the injury to the human body grows larger in proportion to the height of the bed, and if it is higher than 15 m, a fall from it almost certainly results in death.