Researchers from Duke-National University of Singapore and colleagues have found that sleep-deprived individuals experience periods of near-normal brain function interspersed with periods of slow response and severe drops in visual processing and attention.

They used fMRI to measure blood flow in participants who’d been kept awake all night or allowed to sleep (participants were tested in both states). During imaging, they did a task requiring visual attention.

When they had fast responses, all participants had similar patterns of brain activity. However, well-rested and sleep-deprived participants with the slowest responses–also called attentional lapses–showed different patterns of brain activity.

Attentional lapses normally induce activity in frontal and parietal regions of the brain, the “command centers” that can compensate for lost focus by increasing attention. During these lapses, the sleep-deprived had reduced activity in these command centers. They also had dramatic decreases in their higher visual cortex activity–the region responsible for making sense of what is seen.

Society for Neuroscience News Release and Duke University Medical Center news release