Upfront

The lastest findings on sleep deprivation from David Dinges, PhD, made national headlines with such major news outlets as BBC, CNN, Fox News and Reuters. Why all the buzz? The University of Pennsylvania School of Medicine psychologist showed for the first time how our drowsy brains cope with restless nights.

As reported in the May 21 Journal of Neuroscience (Vol. 28, No. 21), Dinges recruited 17 adults to come into his lab and take visual reaction tests while inside an fMRI machine. Some participants came in after a full night's sleep, while others took the same tests after being kept awake in the lab the night before. They repeated the tests the next week, with the rested from the first trial becoming the weary, and vice versa.

Unsurprisingly, the tired participants were slower and less accurate. Looking at the fMRI activation patterns, though, Dinges identified several brain regions that seem to make the difference: Sleepy people's frontal, parietal, visual sensory and thalamic cortices all showed reduced activation. But, curiously, when Dinges compared brain activations during both groups' fastest reactions, he found virtually no difference in frontoparietal activity.

Dinges concludes that when we're sleep deprived, our brains alternate between normal neural activity and an involuntary sleep impulse - that familiar feeling of wakefulness interspersed with bouts of zoning out. A better understanding of how the mind copes with sleep deprivation might help prevent accidents for industrial and transportation workers, medical staff and other people whose jobs often require them to work through weariness.

--M. Price