Emotional memories, sleep and depression
Recent investigations have demonstrated that negative episodic memories are selectively strengthened overnight [1,2], and specifically during rapid eye movement (REM) sleep . Depressed patients show drastic increases in REM  and have a bias towards negative memories . Antidepressants, which are associated with a gradual recovery of mood, typically correct the REM imbalance [6,7]. Based on these data, we have proposed that the strengthening of negative memories during excessive REM may be a factor in deepening and maintaining depression.
Work in our lab has demonstrated that overnight enhancement of negative memory is associated with enhanced connectivity between amygdala and hippocampus , a change believed to occur during REM . A portion of our current work builds on this finding by examiningthe interaction between such strengthening and the altered sleep physiology (enhanced REM) and pharmacology of depressed patients.
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