Saccadic eye movements estimate prolonged time awake.

Area of Science:

• Neuroscience
• Sleep Science
• Human Performance

Background:

• Sleep pressure, driven by homeostatic sleep drive and circadian rhythms, significantly impacts human alertness, performance, and error probability.
• Cognitive functions, particularly attention, are highly susceptible to disruptions from circadian rhythms and increasing sleep pressure.
• Objective, practical metrics for quantifying sleepiness are crucial for safety and performance monitoring.

Purpose of the Study:

• To investigate the potential of using saccades, measured via electro-oculography (EOG), as a non-laboratory metric for estimating total time awake.
• To assess the relationship between saccade performance and sustained wakefulness outside a controlled laboratory setting.

Main Methods:

• Eleven participants performed an 8-minute saccade task, with saccades recorded using EOG every six hours over 54 hours of continuous wakefulness.
• Measurements were conducted outside the laboratory, with participants completing the task on two separate occasions.
• Data analysis focused on the number of executed saccades and its correlation with time awake, accounting for circadian rhythm influences.

Main Results:

• A decrease in the number of saccades was observed during prolonged periods of wakefulness.
• Saccade task performance showed a mathematically monotonous relationship with time awake after removing circadian rhythm effects.
• Individual performance varied, but remained stable within participants, aligning with the three-process model of alertness.

Conclusions:

• Saccade measurements using EOG outside the laboratory show promise as a reliable and objective metric for estimating time awake.
• This method could offer a practical tool for monitoring sleepiness and its impact on human performance in real-world settings.