insomnia. it afflicts most people from time to time. although i haven't suffered from an intense bout for a while, i did once go for about three and a half months without getting a good night's sleep. i remember one person saying that they'd love to have that problem because they'd get so much done. i think i killed them for that. (i'm joking, as far as you know.)
insomnia is often misunderstood as simply not wanting to sleep, i.e., not getting tired. the fact is that insomniacs are frequently tired and with good reason- they aren't getting enough sleep. so rather than bouncing around at all hours, capable of anything, one becomes a bit lethargic, run-down and, what's worse, dull-witted from lack of sleep. your body ultimately doesn't care that your mind isn't getting tired and it's revenge is a sort of work-to-rule campaign.
it's also a common misconception that insomniacs don't sleep at all. the disorder is characterised by the inability to get the rest that your body actually needs. even during bad stretches, it's been infrequent that i've gone for days without any sleep at all. but the problem is, i'm only catching cat naps, which is not what i need. (what's worse is that the acute desire for such naps does not recognise when they may be inappropriate, such as in the office, at dinner with friends, or in the bath.)
a third thing that most people don't realise is that not being able to sleep can be really boring. sure, i'd love to be spending these hours writing, but see my description of the first misunderstanding above. my brain isn't up to any heavy lifting at the moment.
eventually, no matter where you are or how assiduously you cultivate acquaintances in every time zone, there will come a time when the people you know have gone to bed, have other plans, have gone to work, or simply found something more rewarding to do with their time than keep their sleepless friends entertained. so (un)rest assured, you will eventually find yourself alone and wide-eyed in the middle of the night, writing semi-coherently for your little internet nook, trying to think of anything that would get your mind and your body thinking along the same track.