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A sleep EEG measures brain activity and is used to determine if a patient is experiencing all five levels of sleep. Each level is characterized by different brainwave patterns and corresponds to different stages of sleep. Level 5, or REM sleep, is believed to be important for overall health.
A sleep electroencephalogram (EEG) is used to study sleep patterns. Excluding pain, sleep problems are thought to be the second most common symptom of illness, and a sleep EEG is normally used to determine if a patient is experiencing all five levels of sleep. An EEG machine detects and measures brain activity, which shows different patterns during different levels of sleep.
The human brain is made up of cells that must be able to transfer information. They do this using weak electrical impulses, which an EEG can detect and evaluate. When a person has a sleep EEG, small electrodes are attached to their scalp. The electrodes transfer electrical impulse activity to the EEG machine, which then presents the information, usually in the form of a graph.
Sleep cycles are usually characterized by rapid eye movements (REM) and non-REM, which normally correspond to EEG activity. Stage 1 sleep is a non-REM cycle that typically lasts only a short time and is sometimes referred to as drowsiness. During stage 1 sleep, people are usually very easy to wake up. The electrical activity of the brain during this stage is usually quite low.
As sleep transitions from stage 1 to stage 2, a sleep EEG begins to show much larger brainwaves. Stage 2 sleep comprises about 45 percent of the total time spent in non-REM sleep. Most sleep studies show that eye movement is significantly decreased during this level of sleep.
Stage 3 sleep is usually an introduction to deep sleep. During this time, this test typically shows brainwave activity as very large waves, occasionally interrupted by small spikes that are referred to as “delta” waves. During this level of sleep, it is often more difficult to bring sleepers to wakefulness.
When a person finally reaches stage 4 sleep, they are normally very sound sleepers. Sleepers awakened during this level can take several minutes to orient themselves to their surroundings. They will usually be quite groggy and confused. During this level, a sleep EEG mostly shows only delta waves.
Level 5 sleep occurs when a sleeper finally achieves REM-producing sleep, and dreams usually occur during this level. Sleepers sometimes show changes in breathing, blood pressure, and heart rate. During this level, a sleep EEG often shows a wide variety of wave patterns. Most doctors believe that overall health may be related to the amount of time an individual spends at Level 5.
