Lack of sleep had a significant impact on brain responses to an attention task, and circadian rhythms played a role, according to functional magnetic resonance imaging data from 33 healthy adults. The findings were published online Aug. 11 in Science.

Despite the data showing that acute sleep loss impacts cognition, “human performance remains remarkably well preserved until wakefulness is extended into the biological night,” wrote Vincenzo Muto of the University of Liège, Belgium, and his colleagues (Science 2016;353:687-90. doi: 10.1126/science.aad2993 ).

Study participants stayed awake for 42 hours, beginning in the morning and covering 2 biological days, 1 biological night, and part of a second night. They periodically performed the psychomotor vigilance task (PVT), a visual reaction time task designed to measure attention; and an auditory n-back task, and the researchers collected functional and structural MRI data across 13 sessions. The average age of the participants (17 men and 16 women) was 21 years.

Overall, PVT performance was stable during the first day, but decreased significantly after sleep deprivation, then recovered during the second day, and returned to baseline after a period of recovery sleep, the researchers said.

Brain responses to the n-back task were “significantly modulated by a circadian oscillation, synchronous to the melatonin rhythm,” they noted. “This finding rules out a global task-independent circadian influence and suggest the influence of a local, region-specific task-dependent circadian signal,” they added.

Although more research is needed on how different cognitive tasks are affected by sleep deprivation, the findings may help in “understanding of the brain mechanisms underlying the maintenance of daytime cognitive performance and its deterioration, as observed in shift work, jet lag, sleep disorders, aging, and neurodegenerative diseases,” the researchers wrote.

They had no financial conflicts to disclose.


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