Nagasena has stated that there are six causes of dreams, three of them being organic, wind, bile and phlegm. The fourth is due to the intervention of supernatural forces, fifth, revival of past experience and sixth, the influence of future events. It is categorically stated that dreams occur only in light slumber which is said to be like the sleep of the monkey. Of the six causes given Ven. Nagasena has stated positively that the last, namely prophetic dreams are the only important ones and the others are relatively insignificant.
Dreams are mind-created phenomena and they are activities of the mind.
All human beings dream, although some people cannot remember. Buddhism teaches that some dreams have psychological significance. Every single thought that is created is stored in our subconscious mind and some of them strongly influence the mind according to our anxieties. When we sleep, some of these thoughts are activated and appear to us as ' pictures ' moving before us. This happens because during sleep, the five senses which constitute our contact with the outside world, are temporarily arrested.