The state or quality of being watchful; alertness, vigilance or wakefulness.
Continuous watchfulness is maintained around the clock.
1784, Samuel Johnson, letter addressed to Mr. Langton dated 25 August, 1784, cited in James Boswell, The Life of Samuel Johnson, London: Charles Dilly, 1791, Volume 2, p. 545,
Nights of watchfulness produce torpid days […]