How seriously does sleep deprivation impact the productivity and alertness of employees? A classic study compared the effects of sleep deprivation to the effects of alcohol consumption, and showed an identical pattern of impairment.
Intuitively, it’s well known that sleep deprivation will impact your ability to react and think clearly. However, the true impact of sleep deprivation on the ability of employees to function can be difficult to measure. A breakthrough sleep deprivation test conducted by two researchers used alcohol consumption as a benchmark to measure the impact of not sleeping. Alcohol consumption is a useful benchmark as it is recognized that alcohol will significantly reduce the ability to function normally; in addition; many countries have determined the specific levels of alcohol content at which impairment occurs, have set limits for alcohol levels while driving accordingly.
In 2000, researchers Ann Williamson of Australia’s University of New South Wales and Anne-Marie Feyer of New Zealand’s University of Otaga, designed a laboratory experiment comparing the performance effects of sleep deprivation and alcohol consumption. The performance of 39 participants was tested at regular intervals either, over a 28-hour period, for sleep deprivation or after receiving measured doses of alcohol up to about 0.1% blood alcohol concentration (BAC). Eight tests were used in the experiments, measuring everything from hand-eye coordination, vigilance, response speed, accuracy, ability to accomplish two tasks at once, spatial memory, memory and search capability and grammatical reasoning. The tests covered a range of cognitive demands, from simple to complex.
The results were tabulated for a BAC of 0.05% and 0.1%, and for sleep deprivation of 13, 14, 18, 22 hours and 28 hours. At a BAC of 0.05%, not all tests showed a decrease in function, although the decrease was consistent within different types of measures. For example, response speed decreased by 8% to 15%. Hand-eye coordination decreased by 10%. On the other hand, grammatical reasoning and memory and search tests showed little decrease in performance. At a BAC of 0.1%, there was significance performance deterioration across the board — in some cases twice the decrease seen at 0.05%. For instance, accuracy measures decreased by 70%, while hand-eye coordination decreased by 50%.
The results for sleep deprivation showed a similar deterioration in performance. For example, between 13 hours without sleep and 23 hours without sleep, reaction speed decreased by 57% in the vigilance test, 9% in the reaction time test, and 27% in the dual task test. Hand-eye coordination decreased by 26% to 31%, depending on the test, and vigilance decreased by 40%. Once again, grammatical reasoning and memory and search tasks only showed slight decreases in performance.
Comparing the two sets of results, the researchers found the performance deterioration experienced at a BAC of 0.05% was equivalent to the loss in performance after 16.91 to 18.55 hours of being awake. For the passive vigilance test, for example, participants reached a performance level equivalent to the performance at a BAC of 0.05% after just 17 hours of sleeplessness. At a BAC of .1%, the performance results correlated with the results of participants who had been awake for 17.74 to 19.65 hours.
The last tests took place at 28 hours of no sleep. By that time, more than 75% of participants showed performance deterioration in a number of tests equivalent to, and in some cases worse than the performance deterioration levels at a BAC of 0.05%; and for most tests, about 50% of participants showed performance deterioration levels equivalent to deterioration occurring at 0.1%.
This study shows that, using legal limits for driving as benchmarks, employees start to become impaired as early as after 17 hours without sleep, and on average at 18 hours without sleep. It should be noted that most people end their days after 17 or 18 hours, and apparently with good reason. It also means, however, that employees who are ‘burning the midnight oil’ are probably working somewhat impaired; sometimes, the late night cannot be avoided, but employers who encourage long hours from their employees are in fact creating an environment of low productivity and efficiency.
It should be noted, also, that all of the participants in the test were required to have a good night’s sleep before beginning the test; unfortunately, employees who put in late hours tend to do so consistently, which means that their performance would be even more impaired than the performances measured in the study. Employers should take steps to avoid ‘chronic partial sleep deprivation’ if they want employees to be thinking and reacting at their best.
Moderate sleep deprivation produces impairments in cognitive and motor performance equivalent to legally prescribed levels of alcohol intoxication. Ann Williamson, Anne-Marie Feyer. Occupational & Environmental Medicine Journal (October 2000).
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