Can confirm. I was a nuke in the Navy and four hours was probably the most amount of sleep I ever got underway. You work 12-14 days underway and stand 8 and 8 watches then have to wait an hour in line to get chow and then they run drills that the whole ship has to participate in. If you can do get any sleep it's because you hide in the bilge and sleep on pipe or in a ac room.
With a little planing you can get a college education without putting yourself in debt. I did it. Sure you might have to go to community college for the first two years and eat a lot of ramen noddles but it's more than possible with all the grants, scholarships, and employer matching. Most people have no will power and just take the easy way out not thinking about the long term debt they will have.