Certainly makes it harder to hold down on a job. It may even lead to accidents while driving, which makes this a large societal problem.
Stress and poor nutrition also causes sleep disorders, with the same toxic ramifications for people living in poverty.
Another angle on this is sleep apnea. I have this as part of a complex of other medical problems. Originally the fatigue component was treated as a "vague symptom": it didn't even occur to my original PCP to test for sleep apnea. A different doctor who saw me in urgent care ultimately made that referral. But then I went on a wait list for the sleep study for over a year. Who knows when I would have gotten to it before the Affordable Care Act kicked in. As soon as I was on Medi-Cal, I got the sleep study appointmentment in a month. It turned out I was having over 100 "events" an hour. I hadn't been getting any real sleep for years.
The point is that poor people also get much lower quality medical care. Even when they are seeing a doctor, the medical system is predisposed to seeing them as "lifestyle issues" and won't direct them toward expensive tests unless they have the coverage for it. I wasn't diagnosed or treated for sleep apnea until I had the coverage for it: hence, I just had a lot of ongoing blur and fatigue on top of a lot of other medical problems. And I can vouch that this makes it hard to focus and get stuff done, and it makes it that much harder to pull yourself out of your situation.
Capitalism is quite predatory: we need to start protecting people from its worst ravages. Basics like sleep need to be guaranteed as human rights.