Brief reportBrief Sleep After Learning Keeps Emotional Memories Alive for Years
Section snippets
Methods and Materials
To determine long-term effects of sleep on emotional and neutral memory formation, we contacted subjects (healthy men) for a memory test 4 years after they had learned standardized neutral and emotionally arousing text material with a 3-hour interval of either sleep or wakefulness immediately following learning (Wagner et al 2001). To obtain retention sleep with high amounts of slow wave sleep (SWS) and rapid eye movement (REM) sleep, respectively, the 3-hour intervals after learning were
Results
Overall, subjects performed well above chance in the text recognition test, indicating sufficient test sensitivity of this measure for long-term memory assessment (48.9% correct recognition, p < .01 for comparison with 33.3% chance level). Frequency distributions of correctly recognized text topics across experimental conditions showed that sleep after learning specifically enhanced long-term retention of emotional texts (Figure 1). This was confirmed statistically in the hierarchical loglinear
Discussion
The present study investigated for the first time memory effects of postlearning sleep on retention of neutral and emotional memory contents over extended time intervals of several years. The results demonstrate a highly significant and long-lasting impact of only a short period of sleep taking place within a narrow time window of 3 hours immediately after learning, specifically on emotional memory formation. The effect cannot be attributed to influences of superior subjective levels of
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