I don't know how other's insomnia works, but mine works such that I NEED to sleep when I'm tired, which could happen at any time. Then, I seldom sleep for very long.
If I get under 8 hours of sleep (which happens all the time), I'm a complete wreck. It's really difficult.
Like last night, a rather good night all things considered. It took an hour to fall asleep, I woke up after about 4 hours, couldn't get back to sleep for another 3 or so, then slept another 2. So, that's 10 hours out of my day to get 6 hours sleep, and I'm nowhere near 100% since I'm still 2 hours behind in what I need (even ignoring that the disjointed nature of the night makes what I got be less efficient). All this, on what's a GOOD DAY for me.
Anything other than a consolidated 8 hours leads to headaches that make it incredibly difficult to function. Forget mental tasks (like WORK), even eating three meals a day or simply leaving the apartment is extremely difficult. In each of the past 2 weeks (since I've been writing this stuff down), there's been 3 days when I didn't manage to go outside at all, and one day that I was practically bed ridden due to exhaustion (and still not getting the needed sleep).
If I were working, I wouldn't even have the chance to catch up on any of the missing sleep. I'd need to operate on half the sleep I needed for the day, and I'd spend the entire day simply trying to keep awake (often failing), nevermind get any work done. That's what happened all the time at my job last year.
Does that sound like a plus?