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Losing Sleep Impairs Frontal Cortex Function: Presented at SFN
By Roberta Friedman, PhD
NEW ORLEANS, LA -- November 14, 2003 -- Lack of a night's sleep is paid for the next day in impaired function of the frontal cortex, as measured by electroencephalograph (EEG) potentials. This finding was reported here November 11th by sleep researchers at the Society for Neuroscience 33rd Annual Meeting.
Amplitudes of components of the EEG taken over the frontal and parietal cortex changed significantly in people kept awake in the lab overnight. According to study investigator Roger Godbout, PhD, professor of psychiatry, Université de Montréal, Montréal, Québec, Canada, "sleep deprivation has [a] specific impact on the frontal cortex." The findings of this study, he added, demonstrate "how sensitive different cortical systems [are] to a sleep disorder."
Ten young, healthy volunteers spent a night in the lab, kept awake by playing cards and watching videos. Event-related potentials over frontal and parietal cortex the next day revealed different deficits, depending on whether tasks required accuracy or rapidity.
If a novel choice appeared in 1 of the tests, a parietal-lobe potential related to novelty gained in magnitude after sleep deprivation.
"When you are sleep-deprived, you are recruiting more parietal resources [because the frontal lobes are impaired]," said Dr. Godbout. "The parietal lobe counterbalances for lack of frontal function," Dr. Godbout stated. The frontal cortex is thought to govern so-called executive function, such as decision making, which matures only at the end of adolescence. The difference in parietal signal was statistically significant (P < .05), he said.
Sleep deprivation also resulted in subjects using more frontal-cortex resources for accuracy. The event-related potential recorded over the frontal lobe of sleep-deprived subjects was more negative compared to that recorded after a normal night's sleep (P < .05).
The next stage in the research will be to test different psychostimulant drugs to see how they affect these cortical signals, Dr. Godbout said.
[Study Title: Effects of sleep deprivation on event-related brain potentials. Abstract 616.6]
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