Yep, seems somewhat ironic that a condition that causes such profound fatigue causes such significant problems with sleep... In fact becoming too fatigued by CFS actually worsens my ability to sleep, and apparently that's typical among patients with my condition.
In the early stages of CFS it is not uncommon to sleep A LOT (hypersomnia) but once you get into the chronic stage, often sleep becomes elusive. Sleep reversal is a very frequent problem, but allowing yourself to become nocturnal becomes a bit of a problem if you want to stay in touch with the majority of society- although it's fine if you only ever want to talk to hamsters... (Hmm, tempting...) It's often impossible for CFS patients to get to sleep until the early hours of the morning, but then often they can sleep into the afternoon the next day (if they don't have other commitments), this is a really frustrating problem, and is one that can easily become a cycle that is difficult to break. Often before holidays I get warned by someone medical to be very careful not to let my sleep pattern slip.. And it normally does... And I normally have difficulty getting it back to anything like something normal..
My biggest problem in terms of sleep is normally pain. Pain is one of the hardest symptoms to ever ignore. I'm on epilepsy meds to dampen down some of the ridiculous messages going on in my nervous system, but even with these my pain isn't very well controlled. I have codeine that I take as needed, but it's not something that I want to be reliant on in order to get any sleep because of problems with tolerance and dependence (tolerance, dependence and addiction have very different meanings by the way, but that's a whole separate matter).
The emotional consequences of the illness can also interfere with sleep at times. If you're worried about getting all your work done, worried about which medical appointments you've got coming up, worried what they'll say at said medical appointments, worried how you're going to manage to do X, worried how your symptoms are going to be tomorrow, worried about the future etc, its no wonder you can't get to sleep very easily. Surprisingly this is normally not the main reason I can't sleep though.
I can't honestly remember whether I ever got over-tired when I was well and couldn't sleep as a result- I think normally I just wasn't tired enough. Getting over-tired is like when you get past the stage of feeling hungry- you're still hungry, in fact you're even more hungry, but you lose the desire the eat eventually, but it feels great when you finally do. With CFS you get overtired to the point where you can't sleep, and the longer the problem goes on, the more tired you get, the worse you feel and the harder it is to get the much needed sleep. Thankfully after a few sleepless nights your body does eventually relent and you do fall asleep- but not before you've had some frightfully difficult days feeling dreadful.
Another thing is that sleep with CFS is not restorative. You never wake up feeling refreshed and like you've had a really good nights sleep, no matter how long you've slept. There have been sleep studies on CFS patients showing that we don't go into deep sleep for long enough, so the physiology backs up how we feel; although knowing we're right to feel rubbish doesn't make feeling rubbish feel any better..
So yes, CFS is a pretty stupid illness really- it makes you tired but stops you sleeping, and even if you do manage to sleep, you wonder why you bothered..
.. And apologies for rambling and any spelling mistakes etc- I'm writing this at 5 to midnight because I can't sleep- I wonder how I thought of the topic...