REM Sleep (rapid eye movement sleep) is the mentally active sleep time in which dreaming occurs. In humans this active period of sleep is characterized by intense activity in the brain and rapid bursts of eye movements (REM). The discovery of REM sleep patterns has lead to the treatment of sleep disorders - insomnia, sleep apnea (a medical condition which should be evaluated by a physician) and intense interest in lucid dreaming.

One-third of our life is devoted to sleep. The need for sleep overpowers all other physical needs. It appears that sleep benefits the mind more than the body. Without sleep people can become disoriented or psychotic.

Sleep may look like a passive activity. Sleep is a dynamic bodily function. During sleep, blood pressures, heart rate and other body functions such as muscle activity and brain waves rise and fall in a specific individual pattern. Sleep patterns shift from periods of very rapid eye movement and rapidly changing brain waves that alternated with periods of deep, quiet, sleep marked by large, slow brain waves. It was discovered that the body is paralyzed during REM sleep.

When a person is awaken during REM sleep almost everyone can remember their dreams. When a person is not deliberately awaken they may not recall their dreams the next morning. Researchers discovered that dreams vary in length according to the length of the REM period. Because a dream seemed like a fleeting event individuals do not realize just how long their dreams can be.

Non-REM sleep has four stages which equal about 75 percent of total sleep. In each stage, brain waves become progressively larger and slower, and sleep becomes deeper. When the fourth stage is reached (this is the deepest sleep period), the pattern reverses. Sleep becomes progressively lighter until REM sleep, the most active period, occurs. For most people this cycle occurs about once every 90 minutes.

How does the brain do this?

REM sleep begins in the pons, a structure in the brainstem, and neighboring midbrain regions. The pons sends signals to the thalamus and to the cerebral cortex, which is responsible for most thought processes. It also sends signals to turn off motor neurons in the spinal cord, causing a temporary paralysis that prevents movement.

Why sleep is important

Scientist discovered that about 70 million Americans have a sleep disorder. These disorders include insomnia (difficulty in falling asleep) and sleep apnea (a person stops breathing for extended periods during sleep). These can cause behavior problems and accidents related to fatigue.

The brain is a highly complex and complicated organ. Scientists and researchers have made great strides in understanding patterns and functions of sleep. Yet more is unknown than known about sleep.  Today we know that sleep phases are closely related to the activity of certain groups of nerve cells releasing brain chemicals that relay information from one neuron to another.
     

When people sleep, they experience periods of Rapid Eye Movement. During this stage, which is associated with dreaming, the brain becomes very active. REM sleep and dreaming are triggered by the pons and neighboring structures in the brainstem. The pons sends signals to the thalamus and the cerebral cortex -- which is responsible for most cognitive activities. The pons also sends signals to shut off the neurons in the spinal cord.