Most dreams are insignificant and are generated by one’s thoughts during the day.[1] On the other hand, there is a concept that dreams are 1/60th of prophecy.[2] Commentators explain that just as full prophecy used to be revealed in a special type of dream, so too, when there is no prophecy, semi-prophetic messages can be conveyed through a dream. In the era of prophecy, it would be clear to a prophet that he was receiving prophecy and what its meaning was. Similarly, a semi-prophetic dream is likely to be more powerful than a regular dream and, if it causes the dreamer to be shaken emotionally, it might be a sign that he should take it seriously.
Although the exact understanding of the Talmud’s approach to dreams is elusive, a short excerpt may be instructive: “Rabbi Yochanan said, ‘One who had a dream that depressed him should have it interpreted by three people.’ Have it interpreted? Didn’t Rav Chisda say that an uninterpreted dream is like an unread letter [in other words, it will be less likely to have an effect]? Rather, what was meant is that he should go to three people to ‘improve it’ (hatavat chalom).”[3]
From this and other Talmudic discussions we see our Rabbis’ view on four possible reactions to serious, negative dreams: 1. The dream is interpreted negatively – this is potentially dangerous. 2. The dream is suppressed – this is a relatively safe response. 3. A hatavat chalom ceremony (found in some siddurim) is performed – a good idea for people who are worried. 4. One fasts on the day of the dream to overturn possible negative decrees that were revealed – this may prove especially effective, as the dream might be a warning to the dreamer to repent in order to avert a potential negative decree. One may fast for this purpose even on Shabbat (which is usually forbidden). Nowadays, since we don’t always know how to recognize a significant dream, step number four is often extreme.[4]
In summary, there may be reason not to reveal an upsetting bad dream.[5] If one is particularly upset, he can perform a short ceremony and/or fast. The best advice is probably to train oneself not to take dreams too seriously. Nevertheless, if an especially powerful dream or a person’s experience causes him to take them as potential signs of the future, he can consider the aforementioned steps.