Sleep and the Brain
The brain is active when we are asleep but it is only partially processing information from the outside world. While we are asleep, there is a "wall" between the outside world and the conscious mind; however, the "wall" can immediately come down. We filter out important information such as an alarm clock from less important information such as background music. Sleep has its own pattern of activity. When awake, beta waves, rapid but low-energy waves, register in the brain. When relaxed or drowsy, our brain switches to alpha waves which are slower and slightly higher energy waves.
The first major form of sleep is non-REM which has few eye movements that are slow rather than fast.
Rapid Eye Movements (REM) are quick movements of the eye that occur during sleep and researchers believe they mark phases of dreaming.
REM is called paradoxical sleep because, while brain activity resembles those recorded during waking consciousness, the sleeper appears to be deeply asleep and is incapable of moving because of paralysis of the body's voluntary muscles.
- Heart rate increases and becomes irregular.
- REM is 20% of an adult's total sleeping time.
- Sleeper is hard to awaken during REM.
People deprived of REM sleep show a rebound effect when allowed to rest undisturbed, and they spend more than the average amount of time in REM sleep.
Research also indicates that both human and nonhuman subjects spend more time in REM sleep, after learning difficult material.
Each night adults experience 4 to 6 different cycles of non-REM and REM sleep, each lasting about 90 minutes. Click here for a video clip of sleep patterns.
