Deep sleep stores facts while dream sleep stores skills

Much of what sticks from studying gets locked in while you sleep. Deep sleep files away facts, while dream filled sleep locks in skills.

It starts during the day. What you see and hear is briefly recorded in nerve cells as short term memory. That trace then travels to the hippocampus, a memory center that strengthens the involved neurons. Through neuroplasticity, the brain's ability to rewire itself, the brain grows new links between nerve cells and builds a stronger network for long term memory. Memories formed with strong feeling get recorded even better, because of the hippocampus link to emotion.

Sleep then does the heavy filing. Sleep comes in four stages, and the two deepest stages are deep quiet sleep and REM sleep, the active dreaming stage. Recordings of brain waves show electrical pulses traveling through a relay chain linking the lower brain to memory and thinking centers during these stages, which help form memories.

Each stage handles a different kind of memory. During deep quiet sleep without dreams, fact based memory, the facts, names, and formulas you can state out loud, rests briefly in the front of the hippocampus. Signals pass back and forth between the hippocampus and the cortex, the outer layer of the brain, reactivating the memory again and again until it is gradually moved into long term storage there.

The dreaming stage, when brain activity looks a lot like being awake, helps fix procedural memory, the skills and habits you learn by repetition. The research suggests, though not as a proven rule, that sleeping about three hours after memorizing formulas and about one hour after practicing musical scales would be most ideal for holding onto each kind.