vigilance

• Keep your eyes peeled

  To look very carefully and be on the alert for something specific or anything unusual.

• Have eyes in the back of one's head

  To possess an exceptional level of awareness, seemingly able to perceive everything happening around oneself, even things out of direct sight.

• Sleep with one eye open

  To remain extremely vigilant and cautious, even while resting, due to a sense of danger or unease.

• Have eyes in the back of your head

  To be exceptionally observant and aware of everything happening around you, even things out of your direct line of sight.