The brain, an electrochemical organ, is known to produce electrical activity. The 100 billion-odd nerve cells in the brain communicate by sending and receiving electrochemical signals. When millions of neurons, transmit electrical signals simultaneously, this combined electrical activity generates a 'wave-like' pattern, commonly referred to as brainwaves. Different kinds of brain waves are generated depending upon how attentive or focused we are in any kind of activity. For instance, when we are fully involved in some kind of activity, the brain produces beta waves, which are considered to be the fastest. During sleep, the slow delta waves are generated. The following Buzzle write-up discusses the alpha waves that have been associated with passive alertness.
Alpha brain waves that travel in the frequency ranging from 8 to 12 Hz are produced in the thalamus. They are slower than beta waves and have been associated with a relaxed state of mind. Alpha waves are generated when you simply lie down and relax yourself. When you close your eyes, there is sudden burst of alpha brain activity, which eventually dominates the entire cortex area. This is the beginning of the relaxation process, that precedes the sleeping state. Alpha brain waves are also dominant in the early stages of meditation.
In the alpha state, a sense of relaxation prevails, but that does not mean you feel drowsy or sleepy. This state of consciousness is often described as a state of relaxed wakefulness or effortless alertness in which the person is mentally and physically passive. When alpha waves are dominant, you loose focus and tend to breathe slowly. Negative mind state eventually disappears, and you are in a position to nurture positive thoughts. No wonder, you feel much better staying in the alpha brain wave state.