Depending on the dominant frequency, we now classify these brain waves into Alpha, Beta, Delta, and Theta waves, or rhythms. Alpha waves (8-12 cycles per second) seem to occur most often during relaxed meditation. Delta waves (1-3 cycles per second) are most prominent during deep sleep. Theta waves (4-7 cycles per second) seem to be associated with mood. Beta waves (13-22 cycles per second) seem to be associated with the frontal area of the brain, where complex mental processes are handled.
There are many interesting subjects associated with these various waves, but we will concentrate on one. It is thought that our brains are capable of creating only one dominant variety of these waves at any one time. Associated with this, simple monitors and feedback systems were developed which became fairly popular with the public. In the 1970s, many inexpensive "Alpha wave monitors" were sold. Such devices use medical-style skin sensors (GSR) placed next to specific areas of the forehead or skull to sense brain activity and they included simple filters to identify the dominant frequency in the brain waves being produced. Actually, even better results could be had if people were willing to shave small areas of their hair off, as is done for medical EEGs, but most people would not put up with that! Interestingly enough, when a person was thus aware of his/her own production of Alpha waves, that person could usually quickly learn to consistently produce them, even though no one knows exactly how that is accomplished.
These many products were sold primarily to people who were looking for a method of attaining a meditative state. Since such a state was when Alpha waves were dominant, an Alpha-wave feedback monitor often assisted in achieving this end.
As mentioned above, it has always been assumed that our brains are capable of creating one dominant type of these waves at any one time. However a person achieved the production of Alpha waves as a result of using such a monitor, he/she apparently simultaneously reduced the production of Beta waves of analytical thought.
The human brain has bilateralism, that is, it is composed of two cerebral hemispheres, the left and the right. Each hemisphere is capable of storing and processing information on its own, independent of the other hemisphere. There is a separate portion of the brain that interconnects the two, called the corpus callosum. In certain severely epileptic patients, a surgical procedure that cuts the corpus callosum is done. Effectively, this operation entirely separates the functioning of the two nearly fully functional half-brains. The people are then generally said to have a "split-brain". Apparently, that operation stops some "feedback loops" from occurring and causing the epileptic seizures. The left hemisphere generally normally includes verbal abilities, so such patients could describe many things and a good deal is known about that half. The right hemisphere does not generally include verbal abilities, so it has been much more difficult for researchers to fully learn about that half.
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Further research has shown that, in healthy humans, the fibers of the corpus callosum do not even mature until about one year after a child is born, and the process continues until around ten years of age. A child therefore might not develop an integrated both-hemisphere consciousness until several years of age.
Somehow, there must be some advantage of having each half start the learning process independently.
Like a human, a dolphin has a corpus callosum connecting the two hemispheres of its brain. The really useful information here is that a dolphin can apparently control the passage of information through the corpus callosum. When one hemisphere is to sleep, messages from the other, somewhat active hemisphere are apparently somehow not passed to it. However, during waking periods, the corpus callosum apparently operates as it does in humans, with two-way communications between the hemispheres.
There IS a potential alternative understanding, in that the corpus callosum just naturally has little activity in a dolphin's life, and that their brain always acts like two separate brains!
I have grave concerns on whether this is a good idea or not! The physical, mental and emotional implications and consequences of never actually sleeping are entirely unknown. It seems very likely that at least some bad results would occur. In addition, during each of the two (different) semi-waking states, very different capabilities and abilities and possibly even personalities may exist. There may turn out to be no actual benefit for humans from never actually sleeping in a traditional way.
Horses may demonstrate another example of this. Many horses get "spooked" if someone rapidly goes around behind them, disappearing from the sight of one eye and appearing in the vision of the other. A horse's corpus callosum must not be very effective or active (although post-mortem autopsies have shown that it is fully developed), because the two halves of its brain seem to have almost entirely independent existence. This is also related to why riders always mount a horse from the left side, because that eye/hemisphere is familiar with the concept (because nearly all trainers teach the horses to expect that), while the other eye/hemisphere generally panics if a rider attempts to mount from the opposite side.
That bird evidence does not (yet) include EEG recording to confirm that half the brain is actually in a sleep mode, but so much evidence has been collected to strongly imply that.
Other investigators have watched groups of birds resting on a utility line wire, and have seen the same patterns. The endmost birds do not seem to sleep as deeply as those birds in the middle of the group. In addition, some investigators have found that the birds sometimes briefly fly up and back down to land in different places in the pattern. The speculation is that the birds are taking turns at being the end guard birds! Far more investigation is needed regarding such intriguing subjects! There does not seem to have been very much funding for such research, so very few scientific studies have been done. Apparently, politicians do not see any value in knowing how birds sleep!
Researchers have also indicated that many other animals might have similar ability, of INTENTIONALLY controlling full- or half-brain sleep! This MIGHT suggest that it is something that humans might be able to learn.
I am not sure whether it is possible to attach an EEG to a bird!
Rather than the previous one-mode monitors, such monitors would need to be able of separately monitoring the two separate activities of the individual brain hemispheres on a continual basis. A radio transmitter could send the signals to a receiving monitor.
Such continuous monitoring should identify whether dolphins have REM (paradoxical, or rapid-eye-movement) sleep with dreams and whether they produce the various brain wave rhythms as humans do. It should also provide evidence of the process of the transition to their semi-sleeping state. As one hemisphere drops into Delta sleep, is the other necessarily in Alpha mode or is it still possible to accomplish the more advanced activities of Beta levels? Is there some specific sequence of states that precedes the semi-waking state?
Depending on the results from these experiments, it might be possible to develop dual-mode Alpha wave feedback monitors for humans. In whatever way that we can use feedback to create Alpha waves with a conventional Alpha wave monitor, it might be possible to learn to separately create Alpha waves in one hemisphere or the other. If the brain could be conditioned to accept its two hemispheres in different states, implicit inhibition of the activity of the corpus callosum would be the result. Learning to then have one hemisphere create the Delta waves of deep sleep might become possible, while still retaining some level of wakeful state in the other hemisphere.
This possibility would seem ludicrous, except for the fact that all dolphins and most birds already seem to be able to accomplish it!
Since dolphins, porpoises and toothed whales are VERY closely related, it also seems likely that these other species might also have this unique sleeping method. I am not aware of any research that has ever been done to investigate this in whales. Since whales are so large as to not be so endangered by predators, it might be possible that this capability did not develop in them. It might be valuable to also investigate whether any fishes have such a capability, which would allow them to have an awareness of predators, even when 'asleep'!
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C Johnson, Theoretical Physicist, Physics Degree from Univ of Chicago