There are no records of a human having been intentionally kept awake long enough to kill them, but a hereditary disease called fatal familial insomnia suggests there is an ultimate limit.

However, he said, understanding the molecular nature of this single genetic defect, which is at the root of a familial form of such a complex disease, offers invaluable clues.

Mutations in the DLST gene may be responsible for the familial Alzheimer disease (1).