German scientists, publishing research in the November, 2006 issue of the online journal, Nature have found that stimulating the brain during sleep improves memory. The subjects were asked to memorize pairs of words before sleep. During sleep, one group of the subjects received slow, oscillating electrical current that mimicked brain waves. The stimulation was low energy and caused no discomfort (in fact, the subjects could not feel the stimulation at all) or side-effects. The other group was given sham stimulation.
The group receiving the electrical stimulation had significantly better memory retention than the control group—about 8% better, which is significant. The scientists believe that the stimulation improves the function of the hippocampus, which is one of the first areas of the brain to be affected by Alzheimer’s disease.