I cannot tell you too much about Saturn in the 12th,other than, I have it too. And I have dealt with insomnia for many many years. Restless Leg Syndrome here as well. But that may my Gemini moon in the first or my Virgo sun in the 4th.
I analyze everything and then worry about it!!
Interesting about the karmic ties with dad. I am very close with my father. Hmmm........

I have saturn on the 12th house cusp --as I get older I've not been sleeping as deeply or for as many hours as I used to, but I never have any trouble falling asleep when I want to. However, I also have Neptune in 12 :)

Hmm.. I have both saturn and uranus in my 12th in sagittarius... which seems to be an interesting combo :). Sleeping is definitely not as easy for me as for most people. I can't sleep in cars, boats, trains or planes... I'm also completely unable to take naps during the day or otherwise sleep at odd times.

As long as I have a regular sleeping schedule however, I've got no problems falling asleep. I do sleep very deep however, and I nearly never remember my dreams (I have this dream diary and I only write something in there about once a month or something).

I don't know about the karmic ties with dad, though...

i have Saturn in 12th, too.

i am totally a nocturne, and a willing "insomniac" (i'd walk around the house living the night as if it were day, and won't bother to go to bed because i hate to just stay in one place doing nothing for a long period of time)... i can stay awake for 48 hours straight although i'd be dead tired by then... but then i'd get such deep sleep after that... but it's not really healthy, is it?

but then if i go to bed i generally can go to sleep fairly quickly and sleep is disrupted. but these days i am getting addicted to Bath and Body Works' aromatherapy sleep-inducing pillow mist...

of course, other factors are to be considered, like... Scorpio rising (moderation out of the equation), Venus sq. Jupiter (over-indulgence in whatever i was doing), Saturn conj Pluto (can continue job and hold on to the end despite difficulties like need for sleep)... also, i've read somewhere that Cancers (my Sun tribe) are nocturnes...

***
Saturn in 12th house:

koti.mbnet.fi/neptunia/essays/fear8.htm

not meaning to scare anybody, but Sylvia Plath the suicidal poet had that placement, too. (She died during her SR.)
she also had sun-square-saturn (like me... i also have Cap moon. and was born on a Saturday.
oh Saturn, my father!!! please don't kill me when you return for me...)

Depression had almost been constant, it was very serious in my late adolescence; but I was able to hang on and now I wouldn't change my history for any sunshiny thing... I know some things that always-been-happy people could not get. for one thing, i know my own strength. yay.....

***

In psychology, chronic sleep problems usually indicate psychological issues, depression being the usual verdict.

i have suffered my whole life from a different sort of sleep problem---finding it HAAARD to wake up---real hard(tho i fall asleep very easily---in fact i can get heavy-lidded sleepy like i must pull off the road to sleep or else--after 20 minutes of driving! nope--do not have narcolepsy--was tested for it. i have gemini on 12th cusp, ruled by mercury in 4th h libra. my saturn's in 8th--so maybe saturn's not the only culprit here.

I was doing someone's chart, and he had Saturn 12th. I asked him if growing up he had more sleep problems than he does now (he's older, and saturn usually get's better with age) He talked about a time in his childhood where he was under alot of sleep study because he hardly ever slept. Almost complete insomnia.

....Saturn 12th can in some ways deal with difficulty letting go, and sleeping is the ultimate surrender.