Napping often dream mainly because the nap time is relatively short, the body can not enter a deeper level of sleep, which leads to dreams. At the same time in the daytime the brain is generally in a more active state, this situation sleep cortical cells are also in an active state, resulting in a mild increase in nerve sensitivity, will also cause dreaming. In addition to the daytime nap when the external environment is unstable, such as more intense light, more noise, etc., the interference of these factors will produce stimulation of the body, thus causing an increase in neurosensitivity, resulting in naps when dreaming. If the patient itself is too much psychological stress or thinking about the problem, will also affect the quality of naps. After the emergence of a cold, fever or bronchial inflammation, affecting the normal ventilation, ventilation function, resulting in relatively low oxygen content in the body, can also cause dreams during naps.