Insomnia.
My nighttime spring was always wound tight. From childhood to late middle age, sleep and myself were barely on a first-name basis. It was an artifact of hypervigilance, where the adrenal fight-or-flight response was permanently lit. Possibly it originated in infant abuse by a violent father. Can't say, but, that's plausible.
Granted the pointlessness of staying in bed I'd typically read, with headphones blasting The Who or Led Zeppelin or the Stones. You get a lot of reading done that way. And you come to know those early-to-mid 1970s dadrock albums lick-for-lick.
Depression fucks up your Circadians. Those are, like, little crickets that live in your brain and chirp super loud when it's time to wake up. Just kidding.
Depression interferes with circadian rhythm. Depression and sleep disruption nearly always come as a pair. You sleep way too much, or not at all. Andrew Solomon:
Michael Thase, of the University of Pittsburgh, has observed that many depressed people have substantially reduced sleep altogether, and that insomnia during depression is a predictor of suicidality. Even for those who can sleep, the quality of sleep is substantially altered during depression. Depressed people tend to have low sleep efficiency; they seldom or never enter the deep-wave sleep that is associated with feelings of being refreshed and well rested. They may have many brief episodes of REM sleep rather than the fewer and more protracted episodes typical of a healthy individual. Since REM sleep may be described as a minor awakening, this repetitive REM is exhausting rather than restful. Most antidepressants reduce REM sleep, though they don't necessarily improve the overall quality of sleep. Whether this is part of their mechanism of action is hard to know. Thase has observed that depressives with normal sleep may be more responsive to psychotherapy, and that those with abnormal sleep tend to require medication.
— Andrew Solomon, The Noonday Demon: An Atlas Of Depression (pp. 145-146). Scribner. Kindle Edition.
My pattern may have been atypical, I'm not sure. For most of my life my depression was accompanied by the "crayzass surge of overwhelming somatic compulsion" I've written about here. It seems to be more typical for acute insomnia to develop in older people. Solomon again:
Instead of getting sleepy, older depressed people tend to be insomniac, lying awake at night in the grip, often, of paranoia. They have wildly exaggerated catastrophic reactions to small events. They tend to somaticize a lot, and to complain of an enormous number of peculiar aches and pains and atmospheric discomforts: This chair isn't comfortable anymore. The pressure in my shower is down. My right arm hurts when I pick up a teacup. The lights in my room are too bright. The lights in my room are too dim. And so on, ad infinitum.
— Andrew Solomon, The Noonday Demon: An Atlas Of Depression (p. 190). Scribner. Kindle Edition.
Somewhere, for me, this all changed. Whether it was bupropion or the metabolic evolution of middle age I truly don't know. At some point I realized that I was falling asleep easily, and sleeping right through till dawn. Sunrise is my alarm clock. No need for chirping Circadians.
I now typically sleep six hours nightly. That's still a bit less than most people, but it's 50% more than the four hours which had been usual for me for decades. I'm no longer reading as much, and I've come to be more interested in older musics than in dadrock. But from time to time I do still listen to The Who, Led Zeppelin, and the Stones; and I do still know those albums lick-for-lick.