You may ask _when_ it happens that the dream-wish is able to overcome the censorship. This may depend either on the wish or on the censorship: it may be that for unknown reasons the strength of the wish at times becomes excessive; but our impression is that it is more often the attitude of the censorship which is responsible for this shifting in the balance of power. We have already heard that the censorship works with varying intensity in each individual instance, treating the different elements with different degrees of strictness; now we may add that it is very variable in its general behaviour and does not show itself always equally severe towards the same element. If then it chances that the censorship feels itself for once powerless against some dream-wish which threatens to overthrow it, it then, instead of making use of distortion, employs the last weapon left to it and destroys sleep by bringing about an access of anxiety. At this point it strikes us that we still have no idea why these evil, rejected wishes rise up just at night-time, so as to disturb us when we sleep. The answer can hardly be found except in another hypothesis which goes back to the nature of sleep itself. During the day the heavy pressure of a censorship is exercised upon these wishes and, as a rule, it is impossible for them to make themselves felt at all. But in the night it is probable that this censorship, like all the other interests of mental life, is suspended, or at least very much weakened, in favour of the single desire for sleep. So it is due to this partial abrogation of the censorship at night that the forbidden wishes can again become active. There are nervous people suffering from insomnia who confess that their sleeplessness was voluntary in the first instance; for they did not dare to go to sleep because they were afraid of their dreams—that is to say, they feared the consequences of the diminished vigilance of the censorship. You will have no difficulty in understanding that this curtailment of the censorship does not argue any flagrant carelessness: sleep impairs our motor functions; even if our evil intentions do begin to stir within us the utmost they can do is to produce a dream, which is for all practical purposes harmless; and it is this comforting circumstance which gives rise to the sleeper’s remark, made, it is true, in the night but yet not part of his dream-life: “It is only a dream.” So we let it have its way and continue to sleep.