Observable cues
Eye closure, blink duration, face visibility, and head movement can contribute to an alertness estimate.
Not a clinical measurement
Clinical sleep assessment may use EEG and other physiological signals. A phone or laptop camera does not provide an equivalent diagnosis.
False positives and misses
A robust system must expect both. Sensitivity, lighting, position, glasses, and individual facial behaviour all affect results.
The safe role
A warning can be useful, but it cannot guarantee alertness or make a safety-critical activity safe.
Written by the EyeJolt Editorial Team. Published and last reviewed 2026-07-14. Editorial policy.