funny thing about insomnia...it doesn't make you tired until you should be doing something other than sleeping.
i used to be a chronic insomniac, from about 13 years old. i blamed it on racing. i was always so keyed up about it. i would lie awake in bed and hear our grandfather clock bong every 15 minutes until the wee hours of the morning, and then i would pop out of bed like a jack-in-the-box by 7am. i'd be thinking about races and training and bikes. soon, i added girls to that list. then cars. then money. onset insomnia, i think that's what it's called. as i got older, that eased somewhat and except for the occasional night, i go to sleep fairly fast.
besides onset insomnia, i've always been a very light sleeper. anything can wake me up. then i have the type of insomnia where you can't go back to sleep, or i sleep so fitfully i may as well be up watching trucker commercials on tv. that's the type of sleep trouble i've had the last 6 months to a year. no trouble falling asleep at night (or feeling like i'm going to fall asleep ALL DAY LONG!) but anytime after midnight, it's bad news.
one of my favorite books is stephen king's insomnia. after the main character's wife dies, he finds that he is getting less and less sleep every night. eventually, he is up 24 hours a day. after a while of this, he starts seeing creepy things in the night, and then in the day time. only they aren't creations of his sleep-deprived mind, they are real. like all stephen king novels, they start off with completely believable characters that end up doing completely unbelievable things in completely unbelievable situations, only you believe them because king has such a way with weaving a story. at least i think so.
or, maybe i'm just sleep deprived enough to write completely unbelievable things?