As for how long; it varies from person to person. I have heard some sleeping good after a week, others a month. I wish I could say to you x more days. Sorry it's such a wide range.
Sleep is one of the last things to return. I don't want to see you getting aggravated by this and thinking it won't return. It will!
Meantime, what are you doing to help with sleep? Are you doing any exersizes? How about any OTC non addictive meds? What have you tried?
One thing for sure, don't lie in bed tossing and turning watching the clock. That will produce severe anxiety a lot of times. For me, I noticed if I watched tv or used the computer, I became further stimulated, which pushed me farther from sleep. A engrossing book did the trick. It not only made me sleepy, it made me forget everything I was going through, and the world around me for a few hours. It's something worth trying even if you aren't normally a reader. The book needs to be good, top notch, so pick a subject matter you like, and ask for recommendations. It totally helps relax the mind, evoking sleep.
I'm sure you have heard mention the sleepy time tea, Valerian Root, Melatonin and such. Not all work for everyone, it's hit or miss. Valerian did wonders for me, Melatonin, not so much.
It will come back naturally, though when your in the midst of being bone tired from sleep deprivation, it's hard to believe!
Good luck to you.
Hang in there it will get better! I am on day 28 from Norcos and every day gets a little better. I take Melitonin for sleep and get about 8 hours using them. They are available at any store and very cheap. Keep up the good work and stay positive! That is the hardest part plus lack of energy and motivation for me!