Conscious generalized immobility, in which the musculature remains in the tonic state in which it has been placed voluntarily, is known amongst naval officers, printers and nurses, amongst the last being known as “night nurses' paralysis.” Its duration is of a few seconds or minutes, and it appears to be a cataleptic phenomenon. It differs from cataplexy in that the musculature is tonic, and perhaps hypertonic, with the eyelids open, whereas in cataplexy the subject falls to the ground with muscles limp and eyelids closed, as if asleep.