The study showed test subjects had diminished short-term memory, counting skills and cognitive abilities during the groggy period upon awakening known as sleep inertia, said CU-Boulder Assistant Professor Kenneth Wright, lead study author. The new study has implications for medical, safety and transportation workers who are often called upon to perform critical tasks immediately after waking, since cognitive deficiencies following 24 hours of sleep deprivation have previously been shown to be comparable to the effects of alcohol intoxication, he said.
The study appears in the Jan. 11 issue of the Journal of the American Medical Association. Study authors included Wright and Adam Wertz of CU-Boulder's integrative physiology department and Joseph Ronda and Charles Czeisler of Brigham and Women's Hospital in Boston, which is affiliated with Harvard Medical School.
"This is the first time anyone has quantified the effects of sleep inertia," Wright said. "We found the cognitive skills of test subjects were worse upon awakening than after extended sleep deprivation. For a short period, at least, the effects of sleep inertia may be as bad as or worse than being legally drunk."
Following six nights of monitored sleep lasting eight hours per night, the study participants were given a performance test that involved adding randomly generated, two-digit numbers, said Wright. Based on the results, the researchers concluded the subjects exhibited the most severe impairments from sleep inertia within the first three minutes after awakening, he said.
The most severe effects of sleep inertia generally dissipated within the first 10 minutes, although its effects are often detectable for up to two hours, according to the stu
Source:University of Colorado at Boulder