Physical signs
Heavy eyelids, repeated yawning, long blinks, difficulty focusing the eyes, and the head dropping then jerking back up can signal worsening sleepiness.
Attention signs
Missing part of a conversation, rereading the same line, losing track of a video, drifting from a lane, or not remembering the last few moments are serious warning signs.
Eyes can remain open
CDC/NIOSH notes that a person can appear awake during a microsleep while the brain is not processing information. Camera eye-closure detection therefore cannot identify every microsleep.
Respond early
Pause the task, move to a safe place, and rest. Do not wait for an app alarm to confirm what your body is already telling you.
Sources
Written by the EyeJolt Editorial Team. Published and last reviewed 2026-07-14. Editorial policy.