The age of the individuals seemed to have no effect on the averages of the daily amount of time spent in sleep. Persons under the age of forty differed in no marked degree from persons over forty either in length of sleep or frequency of dreaming. There is general agreement on the point that they get just enough sleep, and that vacations make only a slight increase. The data is not yet sufficient to justify a conclusion as to the average time of sleep at different ages. In reference to dreams, about 15 per cent. report that they do not dream, and about 30 per cent. say they dream “rarely,” “seldom,” or “occasionally.” We are disposed to question these returns on the ground that they give an impression that dreams are less frequent than they really are. The investigations of most experimenters who have made special studies of dreams seem rather to show that the number of our dream-experiences grows as soon as we give our attention to them, just as, on a clear night, a hasty glance at the sky may reveal many stars, but a steady gaze reveals very many more. Our returns are interesting as to the character of the dreams. The favorite adjective used to describe dreams was “rational.” A lesser number of persons said their dreams were “pleasant,” less still that they were “fantastic.” Three times as many persons describe their dreams as pleasant than those who describe them as generally unpleasant. Either Professor Freud’s conclusion is correct, that we tend to forget unpleasant experiences more readily than pleasant ones, or else the dreams really afforded more pleasurable than they did disagreeable feelings. The most typical combination used to describe the nature of the individual’s dream-life was that it was “rational and pleasant.” Less than one-third of all the answerers confessed to having ever experienced nightmare. It should be observed that thus far we have encountered a group of replies from persons who, as a group, are remarkably healthy, normal, and fairly free from worry. Particularly, worry does not seem to be a vice of professors, as only 8 per cent. confess to it. About 17 per cent. of them say they need more physical exercise than they get, which is mostly walking. There is also a gratifying unanimity as to good appetite, simple diet, and absence of need for artificial means of inducing sleep. APPENDIX E BIBLIOGRAPHY It is surprising how little has been written about Sleep, and what a small part of what has been written is worth reading. Perhaps the best book, certainly the most exhaustive, is Marie Manacéïne’s “Sleep,” which contains a full but disorderly Bibliography.