Oculomotor impairment during chronic partial sleep deprivation

Area of Science:

• Ophthalmology
• Sleep Medicine
• Human Factors Engineering

Background:

• Assessing alertness is crucial for safety-critical professions, such as commercial driving.
• Oculomotor function is a potential indicator of cognitive and physical performance.
• Chronic partial sleep restriction can significantly impair performance and alertness.

Purpose of the Study:

• To evaluate the impact of chronic partial sleep deprivation and extended sleep on oculomotor function.
• To explore the utility of oculomotor assessment for monitoring alertness in fitness-for-duty testing.
• To correlate oculomotor measures with sleepiness scales and simulated driving performance.

Main Methods:

• Sixty-six commercial drivers underwent a 15-day study with varying time-in-bed durations (3, 5, 7, or 9 hours).
• Oculomotor parameters including saccadic velocity (SV), initial pupil diameter (IPD), and pupil constriction latency (CL) were measured.
• These measures were correlated with sleep latency test (SLT), Stanford sleepiness scale (SSS), and simulated driving performance.

Main Results:

• Saccadic velocity (SV) significantly slowed with 3-5 hours of sleep; initial pupil diameter (IPD) decreased with 9 hours.
• Pupil constriction latency (CL) increased significantly with only 3 hours of sleep.
• SV and IPD correlated with driving accidents, indicating impaired performance under sleep restriction.

Conclusions:

• Oculomotor measures, particularly SV and IPD, are sensitive to sleepiness and predict impaired simulated driving performance.
• Oculomotor testing shows potential utility in detecting excessive sleepiness and performance deterioration.
• These findings support the use of oculometrics for assessing operational readiness in sleep-restricted individuals.