The REM sleep - Memory consolidation hypothesis

It has been hypothesized that REM (rapid eye movement) steep has an importa nt role in memory consolidation. The evidence for this hypothesis is review ed and found to be weak and contradictory. Animal studies correlating chang es in REM steep parameters with learning have produced inconsistent results and are confounded by stress effects. Humans with pharmacological and brai n lesion-induced suppression of REM steep do not show memory deficits, and other human steep-learning studies have not produced consistent results. Th e time spent in REM steep is not correlated with learning ability across hu mans, nor is there a positive relation between REM steep time or intensity and encephalization across species. Although steep is clearly important for optimum acquisition and performance of learned tasks, a major role in memo ry consolidation is unproven.