The Science of Sleeping

So my sister and her husband are down for a few days for the holiday weekend. At dinner it comes out that my sister, and my brother as well, suffer the same problem as I do when it comes to sleeping. It seems that we, as a family, have a knack for falling asleep at inconvenient times, despite getting "enough" sleep. By inconvenient times I mean in the middle of classes or conversations or what not. I suppose this could be confused with a low grade narcolepsy but I'm not so sure these days. My sister has apparently been to a sleep clinic and they said there was nothing wrong with her. But what I wonder is this: a sleep clinic studies you in more or less a controlled environment, but what if, as in this case, the problem occurs outside of normal sleeping hours or conditions?

To that extent, I propose some sort of portable EEG machine, which would pretty much just consist of electrodes and some sort of miniature data recorder. An iPod sized drive that would record the brain wave data. Concurrently, the patient could make a record of what they do as they go through their daily routine, noting when they slept or when they felt tired and so on. This can then be analyzed to see if there is indeed any problem on the mental side of this or whether this is something more physiologically based.