Is it EDS, by chance? Looking into adrenal fatigue and seeing if that rings true for you might be an option. If so, something like Adderall might help in the short term, but could be devastating longer term (such a heavy stimulant definitely taxes the system.)
Did you used to feel fine on 7.5 hours sleep? When did that change - and does it possibly overlap with periods of calorie restriction? What have you tried so far? How much caffeine do you consume, and when's your cut-off time?
The #1 thing that's worked for me over the almost 20 years of having CFS has been to zealously prioritize my sleep time and quality. (... which is a lot easier said than done, ugh.) Bedtime pills of melatonin and l-theanine, combined with magnesium powder dissolved in water. Dark room, cold enough temperature. No bright lights before bed (installed f.lux on my computer, have nerd-y orange safety glasses if I'm watching tv). And on and on, kind of ridiculous - these don't give me 100% chance of decent sleep, but each little piece makes it at least more likely than not. I too can feel almost punch-drunk all-nighter exhausted from getting "only" 7.5 hours of sleep, even if it's sound - which is really hard to get others to understand sometimes! So I empathize.