But mice that had learned to associate a general physical environment with administration of an electric shock were less likely to do so after sleep deprivation. Sleep-deprived mice spent just 4 percent of their time frozen when returned to this environment the following day, compared to 15 percent among mice whose sleep was not disrupted in the five hours immediately after shock administration.

"It has been suggested that sleep serves a variety of physiological functions, ranging from energy conservation to refreshing the immune system," Abel said. "Another important hypothesis is that sleep regulates neuronal function during memory consolidation. Our findings provide support for this theory, and, by implicating hippocampal-dependent tasks during a specific time window, we have taken an initial step in clarifying the neural effects of sleep deprivation."

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Contact: Steve Bradt
bradt@pobox.upenn.edu
215-573-6604
University of Pennsylvania
8-Jul-2003