This is a report on the findings and preliminary indications of various sleep studies which have been made during the last fifteen years, some by the author who has had a three year National Science Foundation grant. Physiological recordings of mental activity during sleep now make possible more precise determinations of what we dream, when we dream, and what these dreams signify, although, as Freud first speculated, they are closely interrelated with the personality of the dreamer. Foulkes' book indicates the three stages of sleep: REM (rapid eye movement) or vivid dream sleep which occurs four times each night; the NREM sleep which is most important to the organism and where there is some dream activity of a less intense nature; and the sleep onset or hypagogic period. The main conclusions point to the fact that dreams are revelatory and purposive and the ways in which their interpretation can be validated, but beyond that, speculations about ""good"" (i.e. healthy) vs. ""poor"" (i.e. neurotic) sleepers are at this time contradictory and ambiguous... The book is not only clinical but also quite technical in its presentation and is designated for a professional audience; whereas the Luce & Segal Sleep (Coward-McCann- p. 285) can both find and reach the general reader.