This is very interesting. For years, meditation researchers have noted that meditators produce different (often slower) types of brain waves when they meditate compared to "regular" awake states. But we haven't really come up with any great reason how or why these two things correlate.
Typically, when a person closes their eyes, they immediately produce a spike in alpha brain waves (8-12 Hz). The beginnings of meditation also show an increase in these brain wave frequencies. When they open their eyes, their brain waves speed up to produce beta wave states (13-38 Hz). Experienced meditators show greater quantities of even slower brain waves. Theta waves, (4-7 Hz) are found in greater quantities in experienced meditators and in sleep states of normal individuals. Delta waves (< 4 Hz) are also found in sleep and deeper meditative states. Oddly, very experienced meditators show deep states of meditation correspond with very vast brain waves called Gamma waves (>40 Hz).
Research from Brown University using magnetoencephalography (MEG) show that sensory attention correlates with alpha rhythms in the cortex. Additionally, persons who have mindfulness training are better able to regulate localized alpha brainwaves than non-trained individuals. A computer model was also built by the investigators that simulates electrical activity of neural networks and makes predictions about how the alpha waves are produced.
The model predicts that timing and strength of alpha waves can be controlled,
"from two separate regions of the thalamus, called thalamic nuclei, that talk to different parts of the cortex. One alpha generator would govern the local “tuning in,” for instance of sensations in a hand, while the other would govern the broader “tuning out” of other sensory or cognitive information in the cortex."
So, as we gain control of our focus of thought during meditation, we also gain control of our focus of thought on our sensory system and our regulation of our alpha wave brain states. Let's not forget that the alpha wave brain state also seems to correlate with people being able to overcome depressive thoughts or chronic pain signals. There are a lot of correlates in this train of research, but nonetheless, its very interesting.