Sleep Stages Are Important for Thought Process'

Lack of sleep can make you emotionally fragile, vulnerable to infection, reduce physical strength and reduce your ability to concentrate. Prolonged deprivation can increase these problems drastically. All these problems are symptoms of what neuroscientists believe the actual function of sleep is, learning and memory.

Sleep plays a critical role in flagging and storing important memories. It also helps in organizing sensory data, and in making important connections between the data.

REM

Rapid eye movement or REM sleep was first discovered in 1953 by Dr. Eugene Aserinsky. It has been found to be universal and occurs periodically throughout the night, alternating with other sleep states. There is a light stage, another deeper stage before REM, and finally, a very deep stage where the electrical waves become very slow and long.

Scientists have confirmed the link between REM and dreaming. Avi Karni, a scientist in Israel found in 1994 that depriving people of REM sleep undermined memory of patterns they had learned the previous day, but lack of deep sleep did not.

Memory and Sensory Data

Recently studies have shown that the day's information is first gone over, and then separated and categorized. The brain then places them into readable and retrievable sections.

If a persons sleep contains deep sleep, then performance on memory tasks is enhanced, compared to someone's whose doesn't. We normally fall into deep sleep about 20 minutes after falling asleep. We spend an hour or more in deep sleep early in the night, and usually less time through the rest of the night.

REM sleep, which comes later, is important for pattern recognition in sensory data. Things such as playing chess or language would be dealt with during REM.

Chemical Aides

Scientists have found that during sleep the brain is bathed in a chemical bath different than any that happens during waking hours. Inhibitory transmitters increase, and the levels of many activating messengers drop, or shut down entirely. Before REM, a small pocket of cells in the brainstem spurs a surge in glutamate, which leads to protein synthesis that supports long term memory.

This condition helps to clear away the excess information gathered over the day, and important details are replayed and reinforced.

Some scientists say that the brain mixes and matches the memories it has, but much more study is needed. What we do have are many good questions. We need more study on each individual sleep states to discover its exact role in sorting through sensory data.

Obviously, full sleep is important in minimizing the problems we've discussed here. Despite our minimal knowledge of exactly what the brain is doing during sleep, we can all see the detrimental effects of a lack of sleep.