i wonder if that has something to do with getting older.
being tired, for me, is a very interesting state. i imagine it's less interesting to most people, who probably are tired much more frequently than i, having regular jobs and all that. (i probably wake up unnaturally maybe once every two weeks on average.) it's basically the same, except i'm stupider and sadder. i have a reasonable enough autopilot that when i'm mildly tired, i can get through the day (when extremely tired, i make one catastrophic mistake per day, most frequently locking my keys in my car.) but i'm not quite as sharp, and, most fascinatingly, i'm not quite as happy either locally or with my life.
it's weird that a simple lack of sleep can lead to so much discontent. it isn't really the pain of being undesirably awake; i just don't find things as funny or interesting or, well, happy. and i tend more to harp on bad aspects of my life (of which there are blessedly few at the moment, but still two big ones, which readers might be able to guess at) when i'm tired.
it's an instance of the general very strange phenomenon that a lot of times the actual facts of your life don't determine whether you're happy or not. it often happens that my happiness level dramatically spikes or dramatically plummets even though nothing has changed about my life. lack of sleep here is an obvious catalyst, but sometimes these things just happen. it's so strange that there is no intuitive psychological constancy; i don't think it's just me, though maybe it is, in which case i have a chance of making it into the DSM someday.
i guess for me the most common influence is the relationship thing. i've noticed that when i'm in a [happy] relationship, everything happy is 10 times as happy, and everything sad is 1/10 as sad. (actually, upon further reflection, the second part is untrue.) it probably has something to do with framework and hope, but regardless, it's very strange that being in a relationship should influence so strongly how happy i am while, for instance, playing bridge, or listening to a joke.
i mean it's not like i'm miserable today by any means. it's just curious that my happiness level is so much lower due to a simple missing hour of sleep. it hardly seems rational.