Sleep deprivation has a definite effect on learning, memory, and the ability to think clearly. If a person is not able to get a full night's sleep after learning something new, he will not remember the new knowledge well. He will not fully assimilate the new ideas or task until he is able to go through a complete night of uninterrupted sleep cycles.
Different parts of the brain are rested and regenerated during different phases of sleep. During some phases of sleep, the neurons in the cerebral cortex regenerate. If sleep is interrupted so that this regeneration cannot occur, speech may be affected, since the temporal lobe of the brain is what controls speech. People who do not get enough sleep often have slurred speech. There is also measurably less activity in their temporal lobes than in those of well-rested people.
During REM sleep, memories are consolidated and categorized by the brain. New synaptic connections are also formed during REM sleep, aiding learning. If REM sleep is cut short, long-term memory may be affected and new knowledge might not be retained. Conversely, short-term memory might be better in the sleep deprived person because the part of the brain that controls short-term memory has never gone off-line, and the memories are still fresh.
Sleep deprived people are much more accident-prone than well-rested people. This is partly due to the person being groggy or sleepy due to lack of rest. It is also partly due to the fact that sleep deprived people tend to fall into sleep for very brief periods at unforeseen times. These brief periods of sleep are the body's way of making up for its lack of sleep the night...