New research coming out of Brigham Young University shows that there may be a link between how well you can perform visual search tasks and both the amount of sleep you have gotten and what time of day it is.  The findings, which were recently published in the Journal of Vision show that when people are sleep deprived, they experience performance deficits when completing these types of tasks.  Additionally, they found that our perception of how tired a person is has little bearing on how degraded their performance will be on these types of tasks.   This research adds another aspect to the wealth of data that supports the importance of getting enough sleep every night.

The goals of the study were to determine how sleep affects the performance of complex visual search tasks and to gauge if the participants knew how sleepy they were.  The team chose this type of task for the study because it is the type of task commonly completed by people in safety-sensitive jobs like air traffic controllers and power plant operation monitors.  These types of tasks require the person completing them to perform repetitive actions involving memory, visual information retrieval, and making important decisions based on that information.

In order to assess how sleep affects these types of tasks, the research team studied a group of a dozen participants over the course of a month.  The first week people were allowed to sleep 10-12 hours each night.   The baseline performance metrics for the test were set for each participant during this time.  During the other three weeks of the study, participants had their sleep significantly restricted.  Each participant was only allowed 5-6 hours sleep per day on a 28 hour schedule.  Participants were also isolated from knowing what time of the day or night it was for the entirety of the study.

At different intervals throughout the month-long study period, participants were tested on how quickly they performed a series of computer based tasks requiring visual search skills.  During each test, the research team monitored how long it took participants to complete the tasks.   The test featured tasks requiring the participant to locate specific information and the research team compiled data on how quickly and how accurately participants completed the tasks.

The findings were fairly consistent across the participants.  Increases in sleep deprivation showed a corresponding decrease in the speed with which participants could complete their task.  Accuracy, however, was not affected.  This means that as the participants became more sleep deprived, they were still able to accurately perform tasks; it just took them longer to do it.  They also found that once a person is overtired, they have difficulty determining just how overtired they are.  Participants often reported that they weren’t that sleepy but their test results showed they were experiencing a significant performance deficit that was more in line with someone who was very overtired.  This may have real implications for people who work alternate shifts.

There was one other interesting finding that contributes to the case for sleeping at night, all night.  The team found that people who took the test in the middle of the night also suffered performance deficits as contrasted with those tests taken during the day.  Meaning, even when two people get the same amount of sleep, the one who works during daylight hours will be more productive.


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