I Bought a Flowtime head band which provides realtime brainwave data.
I find there are a lot of problems with it.
I'll start with what I like: you can see realtime graphs of alpha, beta, delta, theta and gamma brain waves that shows their amplitudes on the same chart and you can select which to display at any given time. It keeps a record so you can review it after using the device. I used the android app to see the data and the headband connects using bluetooth.
The problem is that it only has sensors on your forehead and scientific researchers use sensors at more/other locations so you don't know if the device is showing what you read about - you don't know if the brain wave intensities you see from the device mean what the scientific research says they mean. If scientists have shown increased theta wave amplitude correlates with increased creativity, if that was measured in the back of the head, then learning to increase theta waves in the forehead might not corrleate with anything similar.
So the main purpose for which I bought the device, to try to see if I could increase certain brainwave types cannot really be accomplished with it. And I am probably going to return it.
There are a lot of other problems:
It doesn't connect to my phone consistently: sometimes I have to go into the android settings and do a force stop and restart the app before it will show the brainwave data.
It shows the combined wave form in real time but not in the saved statistics. I am getting some weird readings where the combined wave form intensity goes way up, off the chart, for a second or so - I don't know what this means, if it is normal, a technical flaw in the device, if I have a brain tumor, seizures or what and I would like to study what is happening to the individual brainwave types after a session, and maybe share it with someone else such as a doctor.
The heart beat monitor doesn't closely agree with the pulse rate I measure by feeling my own heartbeat directly. It uses the heartbeat to calculate other types of statistics so those other measures are not reliable.
From brain waves alone you can't tell if you are concentrating in meditation or on solving a problem, or if you are relaxed because of meditation or because you are falling asleep. So measuring your brainwaves is not necessarily telling you how your meditation session is going.
And the subjective experiences in meditation are much clearer and more meaningful than watching brain waves. I know when I'm relaxed or tense by how I feel, I know when I have good concentration or when my mind is turbulent. I know by feel the different soft jhanas, higher jhanas, metta, afterglow, and other sorts of feelings etc. Looking at brainwaves doesn't give you better information than what you can feel directly, it doesn't really help with meditation.
And I think it is a distraction. My opinion is that people forget that meditation is an tool to accomplish a higher purpose and they become infatuated with meditation and states. But the ultimate purpose of meditation in Buddhism is to be non-attached and to be mindful in daily life (which are the same thing in a lot of ways), to experience nirvana. When people should (in my opinion, if they are aspiring to the goals of Buddhism) be observing the three characteristics, they are instead focused on how well they are concentrating or, for example, on their level of alpha waves. They are neglecting to do the most important thing because they are attached to lesser attainments. (Well, people are trying to wake up through indirect means - attaining states, when they will have a much better understanding of their progress and the dharma in general if they use direct means - observing the activity of their mind. Indirect means work for many people, I am not trying to deny that, just in my opinion I prefer a conscious, intentional, informed path. But what works best for one person is not necessarily the best for everyone.)
So I don't see this or similar devices useful for improving meditation or helping you to progress on the path, or change your brainwaves based on what scientific research has reported.
