Walker and van der Helm: sleep as overnight therapy

Walker and van der Helm, sleep scientists at the University of California, Berkeley, brought together brain-imaging and sleep studies to suggest that REM sleep, when most vivid dreaming happens, helps process emotional experiences.

Their idea is that sleep keeps the memory of an emotional event while softening its emotional charge, so it stings a little less the next day. Later studies have found mixed support, so it remains a promising theory rather than a settled fact.