Brief sleep after learning keeps emotional memories alive for years.

BACKGROUND

Sleep after learning supports memory consolidation. However, long-lasting memory effects of sleep have not yet been investigated. Postlearning sleep may be particularly involved in the long-term retention of emotional memories and could thereby contribute to the development of posttraumatic stress disorder (PTSD), a disease thought to result from overconsolidation of traumatic memories.

METHODS

Subjects (healthy men) who had learned neutral and emotional texts immediately before sleeping or remaining awake for the subsequent 3 hours were recontacted after 4 years for long-term memory assessment (forced-choice recognition test).

RESULTS

Sleep following learning compared with wakefulness enhanced memory for emotional texts after 4 years (p = .001). No such enhancement was observed for neutral texts (p = .571).

CONCLUSIONS

Brief periods of sleep immediately following learning cause preservation of emotional memories over several years. Sleep deprivation in the immediate aftermath of traumatic events could be a promising therapeutic measure to prevent PTSD.