Psychology -> The ways to study sleep
The ways to study sleep
The ways to study sleep: electroencephalograph (EEG), electromyograph (EMG), electro-oculargram (eye movements) and sleep laboratories.
Researchers use many different devices to study sleep and gain information about particular stages of sleep. The most important apparatus of a sleep laboratory is the polygraph. This is a machine which records on paper the output of various devices that can be attached to the person being studied. Sleep researchers use the following devices:
The electroencephalograph (EEG) is used to measure the electrical activity of the brain through small metal discs pasted to the scalp. Changes in brain wave patterns provide psychologists with information about a person's level of consciousness and which stage of sleep they are in.
When a person is awake and alert, the output of the EEG reveals brain wave patterns which are high in frequency (15-30 cycles per second) and low in amplitude. These small, irregular waves are called beta waves. (Try to remember beta = busy, as the person is active and alert.)
When a person is relaxed and somewhat drowsy, the EEG recording shows a higher amplitude and lower frequency rhythm (8-12 cycles per second). These brain waves are called alpha waves. These waves are characteristic of someone falling asleep, entering stage 1 of sleep. (Try to remember alpha = almost asleep.)