Are dreams the brain's start up test ? : New measurements taken by US scientists from sleeping people explain, at least in part, why dreams tend to have such bizarre but vivid story lines. The findings deal a blow to the Freudian interpretation of dreams but leave open the possiblity that some useful personal meaning can be extracted from them. The main purpose of the dreams, however, the authors of the new study believe, is to test whether the brain has had enough sleep, and if so, to wake it up.