There are four main types of brain waves: Alpha, Beta, Delta and Theta, and a fifth - Gamma - that also deserves a mention. Brain waves work a bit like the gears on a car engine, shifting brain activity up and down according to what we are trying to do. Delta (seen only in deep sleep) is a bit like first gear, Theta (light, dreaming sleep and drowsiness) the second, Alpha third, and Beta fourth - with Gamma for a high performance fifth gear.
As with driving, skillful use of gear change can get the best performance out of a car. When we are driving a complex route, we operate mainly in Beta, dipping in and out of the more relaxed state of Alpha - which is good for creative time-out and a bit of restorative daydreaming. Just as there is no benefit to driving in only one gear, we need to create balance and opportunity to match the right level of brain wave for what we are trying to do.
Gamma brain waves are those that resonate at a higher frequency than Beta - typically at 40 Hz and above - and these have become more easily identified since the introduction of digital electroencephalography (EEG) as analog EEG was restricted to around 30 HZ. So although Gamma waves have always existed, they were previously not recognised on monitoring equipment. They are associated with a state of hyper-alertness, perception and integration of sensory input, usually seen in those who train for peak performance in a physical or intellectual capacity, as they are evidence of extreme levels of concentration and focus. But for the rest of us, a good example is when time seems to "slow down" during a car or other accident, for example. This is the brain entering a phase of Gamma waves where our survival may be dependent on the fastest of information processing and reaction times.
For many of us, life is just one long round of Beta wave activity, which is tiring and, in the end, counter-productive as it's impossible to deliver continuously well when utilising only one wakeful state (if you drove a car continuously in fourth gear, you'd wreck the engine). Certainly, consciously working towards more balance between Beta and Alpha waves means a more creative way of concentrating, problem solving and working. Balancing between the two, and dipping into Gamma wave activity occasionally, could serve us even better. Along with lots of Theta and Delta waves at night!