Narcolepsy

[SleepersWife07]

I'm posting this because I really have nowhere to turn at the moment, and I'm at my wits end. For almost 3 years now, my husband has been a very sleepy man. We live in a very small town, and the Dr here seems to know nothing on sleep disorders. Regardless of the amount of sleep he has every night, he is exhausted day in and day out. Most recently, it has come to affect our marriage, and I'm trying desperatly to save us...

In the mornings, he wakes, every day, at 3am (he has to be at work at 5:30). The amount of time it takes him to "wake up" is ridiculous, and I've seen him fall back asleep after coffee and/or energy drinks. Throughout the day, he has sudden onsets of fatigue and/or sleep. This has been going on for a while, but has gotten progressively worse. It doesn't matter if hes sitting, standing, walking, talking, singing to the radio.... he'll fall asleep. The ONLY exception we've found is if he is doing something that seems to involve a lot of brain power, like doing math or video games. Recently, he fell asleep at work while walking and pushing something, which ran into a wall and proceeded to give him whiplash. After the initial adrenaline shock wore off, he was back to his sleepy self.
This has been the cause to many an argument between us, and he gets between 7-8hrs of sleep every night. Once the drowsiness sets in, nothing seems to be able to combat it. One day recently, he poured himself a cup of coffee and put it in the microwave to heat it up. In the 60 seconds that he had nuked it, he fell asleep.
He does not snore, doesn't sleep excessively heavy or light, and doesn't wake up very much. He does get up once a night to use the restroom, but that's due to the high amounts of fluids he always drinks. I have noticed that once he falls asleep, he will start talking within 10 minutes, and its always about something he later recalls he dreamed about.
The Dr here did a full lab panel on him and gave us the troubling report that "all blood work came back normal". We're at a loss, and what was lovingly and jokingly referred to as his passive narcolepsy has now become a big issue. Like I said, his episodes will strike at any time of the day, regardless of what he is doing, UNLESS he's doing something that takes a lot of mental concentration. Mundane things like folding laundry or doing dishes will wipe him out. It will be at least 2 months before we can see the sleep specialist (about 60 miles away), and I know this is a lot of background info, but it is all for one good question...
I've studied some nursing in college, so I know a bit about sleep cycles and brain wave activity. Will narcolepsy strike even if your brain is fully engaged? Or is it possible that there is a form of narcolepsy, or another sleep disorder, in which one falls asleep simply because brain waves fall below a certain level?
Any help that anyone can give me would be greatly appreciated. We are going back into the Dr this week to try other options. Hopefully, with your help, we can find a diagnosis soon.