The rising sun outside the window must hit the wall first, then the face, and then the body. The influence of the sequential change of temperature and light will cause bad dreams in a trance. At this time, the photosensitive signal is fed back to the sleeping computing center to make subconscious stress reactions, such as the feeling of falling into the water, cold body, hot face or being taken to hell, rapid increase of adrenaline, accelerated eye movement, and even suffocation or nightmares. So this sensory-induced imagination is a terrible experience.
From a scientific point of view, the human body contains ferromagnetic elements such as iron, cobalt and nickel, especially the blood contains a lot of iron, so sleeping according to the geomagnetic field can make the geomagnetic field pass smoothly and promote sleep.
In Chinese medicine, the direction of sleep is very important. Chinese medicine says that the human body should "stand pulse" and "stand qi" during sleep. The word "Li" means that the pulse trend in the human body is consistent with the pulse of nature, so that the blood vessels will be unobstructed.