Which statement best describes microsleeps in aviation risk?

• A. Microsleeps can occur with eyes closed and full awareness
• B. Microsleeps always last several minutes
• C. Microsleeps can occur with eyes open and the brain not processing information
• D. Microsleeps only occur during rest periods

Answer: (C)

Microsleeps are extremely brief, involuntary slips into sleep that can happen while a pilot remains outwardly awake. A defining feature is that they can occur with the eyes open, and the brain momentarily stops processing information, so attention and perception lapse for a few seconds. This is why they’re a major risk in aviation: a pilot may miss critical cues, delay responses, or lose situational awareness even though they appear to be functioning normally.

They are not long events; they typically last only a few seconds, sometimes edging into a few more, but not minutes. They’re not limited to rest periods either—they can happen during continuous, demanding flight tasks when fatigue is present. The other statements misrepresent microsleeps: they don’t require the eyes to be closed, they aren’t minutes-long, and they don’t occur only during rest.