Scientists have developed tests for sleep impairment by tracking eye movements. A new report published by The Physiological Society describes the development of simple testing for sleep-related impairment based on a range of movement in the eyes.
At NASA’s Ames Research Center, a team of experts has identified eye-movement measures that can be easily and reliably tested to detect small neural deficits.
When humans operate on a lack of sleep, they are often unaware that they are dangerously affected, yet sleep deprivation is believed to play a role in up to 30 percent of all motor vehicle crashes. Lack of sleep has also been implicated in many catastrophic accidents, including the Chernobyl nuclear disaster.
“There are significant safety ramifications for workers who may be performing tasks that require precise visual coordination of one’s actions when sleep deprived or during night shifts,” said study senior author Lee Stone.
“By looking at a wide variety of components of human eye movements, we could not only detect sleepiness but also distinguish it from other factors, such as alcohol use or brain injury, that we have previously shown cause subtly different deficits in eye movements.”
For two weeks, study participants were instructed to sleep 8.5 hours each night on a consistent schedule and to abstain from any alcohol, drugs, or caffeine so that the individuals started the trial completely rested with no sleep deficit.
Next, the participants spent up to 28 hours awake in the Fatigue Countermeasures Laboratory at NASA Ames, as researchers tested their eye-movement performance periodically to track how it changed throughout the day and night.
By using advanced eye movement scanning techniques, the team pinpointed consistent effects that represented increasing impairment throughout the night for components of motion perception. When participants were asked to track stimuli with unpredictable direction, speed, or starting location, their eye movements were dramatically impaired.
According to the researchers, the findings have important implications for individuals who work in jobs that require vigilant monitoring and precise motor action, such as military personnel, surgeons, and truck drivers. The eye-movement measures could be used to gauge whether individuals are impaired when starting off the work day with a lack of sleep or before working a night shift.
The study is published in the Journal of Physiology.
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