Apart from the demons that are naught but the personification of certain diseases, it does not appear that the demons were limited in their power to one specific kind of action. In other words, sharp distinctions between the demons do not appear to have been drawn. As appears from the extracts above translated, the _utukku_, _shedu_, _alu_, and _ekimmu_ were grouped together, and hardly regarded as anything more than descriptive epithets of a general class of demons. At the same time it appears likely that at one time they were differentiated with a greater degree of preciseness. So the _ekimmu_ appears to be the shadowy demon that hovers around graves, a species of ghost or vampire that attacks people in the dead of night and lays them prostrate. _Lilu_ and _lilitu_ are the spirits that flit by in the night. Of a specific character likewise are the conceptions connected with a demon known as _ardat lili_, 'maid of the night,' a strange female 'will-o'-the-wisp,' who approaches men, arouses their passions, but does not permit a satisfaction of them. Great importance being attached by the Babylonians to dreams, the belief in a 'maid of the night' was probably due to the unchecked play of the imagination during the hours of sleep. Bad dreams came at the instigation of the demons, and such a demon as the _rabisu_ or the _labartu_ appears to have been especially associated with the horrible sensations aroused by a 'nightmare.'[347] Again the _utukku_ is represented at times as attacking the neck of man; the _gallu_ attacks the hand, the _ekimmu_ the loins, the _alu_ the breast. But these distinctions count for little in the texts. _Utukku_ becomes a general name for demon, and _gallu_, _alu_, and _shedu_ are either used synonymously with _utukku_ or thrown together with the latter in a manner that clearly shows the general identity of the conceptions ultimately connected with them. The same is the case with the _rabisu_ and _gallu_, with the _labartu_, _akhkhazu_, and _ekimmu_.