Stimulating the brain with gentle electric currents during sleep boosts memory, German scientists say.
When they applied several currents that mimic natural slow, oscillating brainwaves in sleep they enhanced the memory of medical students.
"It leads to improved memory retention," said Jan Born, a neuroscientist at Luebeck University.
The scientists, whose results were published online by the journal Nature, believe brain stimulation could help people with memory problems and Alzheimer's disease.
Dr Born and his team asked the students to learn a list of words before they fell asleep. The researchers stimulated their brains and after they woke up, the students had to recall the words they had memorised. The students recalled a greater number of words than if they had been given a sham stimulation.
"This is proof that this slow oscillation has a real function during sleep - to build and consolidate memory," said Dr Born.
He believes the electrical currents affect the hippocampus, one of the first regions of the brain that is damaged in patients with Alzheimer's disease.
