From: David A Gabel, ENN
Published August 1, 2012 10:08 AM

Lack of Sleep Causes Slower Cognitive Abilities

Everyone is aware of the importance of a good night sleep to keep one's cognitive and physical abilities at a healthy level. Experts recommend eight hours of sleep as the ideal. However, many people often get only five or six hours of sleep, and many have grown accustomed to that level. It does not bother them one bit that they are not getting their eight hours. For these people, does this lower level of sleep really affect their work in a negative way? A new study has found that regardless of whether or not a person feels tired, a lack of sleep can influence your daily actions for certain tasks.

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The study was conducted by researchers at Brigham and Women’s Hospital (BWH). "Our team decided to look at how sleep might affect complex visual search tasks, because they are common in safety-sensitive activities, such as air-traffic control, baggage screening, and monitoring power plant operations," explained Jeanne F. Duffy, PhD, MBA, senior author on this study and associate neuroscientist at BWH. "These types of jobs involve processes that require repeated, quick memory encoding and retrieval of visual information, in combination with decision making about the information."

To conduct this study, the researchers observed 12 participants over the course of one month. In the first week, the participants were scheduled for 10-12 hours of sleep per night, ensuring that they were well-rested. Then for the next three weeks, they were only scheduled for an average of 5.6 hours per night. Furthermore, their sleep time schedules were based on a 28-hour cycle, mirroring chronic jet lag.

Computer tests were given, involving visual search tasks. The program recorded the speed in which the participants could find important information and how accurately it could be identified.

The results showed that the longer a person is awake, the slower the information was identified. Plus, during biological night time of 12 am to 6 am, the participants, unaware of the time throughout the study, performed the tasks slower than in the daytime.

"This research provides valuable information for workers, and their employers, who perform these types of visual search tasks during the night shift, because they will do it much more slowly than when they are working during the day," said Duffy. "The longer someone is awake, the more the ability to perform a task, in this case a visual search, is hindered, and this impact of being awake is even stronger at night."

The lesson is that the longer one remains on a given task, particularly into the graveyard shift, there are diminishing returns. The study found that as the lack of sleep continued throughout the month, the slower the responses got. While people grew accustomed to the sleep scheduled and reported only slightly less feelings of fatigue, their scores on the visual tasks were significantly slower.

This study has been published in the Journal of Vision.

Sleeping Man image via Shutterstock

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