Werewolves!

There might be something to the folklore linking the moon to human behaviour:

A study in an Australian hospital has identified a spike in out-of-control "werewolf" patients when a full moon is out.

A researcher observing:

Some of these patients attacked the staff like animals - biting, spitting and scratching.

A majority were drunk or drugged, or both, of course.

It is unclear exactly how the lunar cycle might be linked to human behaviour; it probably has something to do with extra night time light provided by a full moon. Regardless, the moon's link to erratic behaviour was once widely accepted, hence the word lunatic, which links madness to lunar phases.

It seems likely that the extra light of a full moon encourages ne'er do wells to be out and about burgling and stealing and such, and that some of them would be substance affected. Naturally some of these folk are going to hurt themselves roaming around in dim light and require treatment -- tripping over unseen bicycles or sprinklers, falling off fences, cutting hands on broken windows and so forth. That they are inclined to bite, spit and scratch is hardly surprising. Lunatics? Yes. Affected by the moon? Probably not.