Like I said: I am just a stranger on the internet. :) There might be other relevant factors in your life affecting you or other things that might help you. I am not a medical professional, but 'to me', your sleep cycle_s_ seem too rough for somebody your age.
If you are eating unhealthy (aren't we all...) maybe dietary supplements* and cutting down on sugar and caffeine might help give you more "energy" in general. But even if you were 'kind of an athlete' there is only so much a healthy/balanced diet can do for you when you're sleep-deprived.
* Not just for you, but for everybody who happens to read this: Don't just take dietary supplements because 'you think' you might need them. Nothing against having a fizzy tablet with multivitamins and minerals and whatnot every now and then, but regularly taking stuff your body doesn't need can actually harm you. It may sound blown out of proportion, but consult your family doctor to determine what your body has a shortage of - especially if you're not feeling well already.
Yatsufusa
I wish I could tell you something different, Boss, but as you describe it, it seems to me that you bit off more than you can chew. Being exhausted means you will absorb 'less' of what you "learn".
The option promising the most "success" would be scheduling your online courses to the weekend, if possible. But you need to relax at some 'point'...
Depending on where you work, talking to your employer about doing less hours could be an option - if you can afford the pay-cut. Unless you plan on leaving them afterwards, the prospect of having a more qualified employee "should" be appealing to most places of work.
Other than that... The core of your problem is that the day does not have enough hours. If you can organize occasional help from friends and family (or straight up 'pay' somebody) to go grocery shopping for you, that would save some time and reduce stress. Similar with cooking and cleaning.
There are services who deliver ingredients & recipes to you. (Your favorite 'online content creators' probably have a discount codes for you.)
The only thing that will not only _not_help_ but will actively make you worse in all aspects of your life is "trying to push through", ignoring the problem while your body is already ringing the alarms. You can force yourself to reach the finish line if it's not far away anymore. But from how I understand you, that is not the case.
We make some of our worst decisions when under pressure, when we're sick, tired, or otherwise "not ourselves". It's the adult thing to ask others for help when you become aware that you are out of your depth. But at the same time the things I suggested are all very general advice. Most of the people who will read this do not know you very well. You should discuss this with somebody who 'does' know you and has a better idea about what your options are.
(The only thing's 'I' "know" about you are things I can extrapolate from a glance at your NG profile.)
Boss
Youre very right! The thing is that a 2 and a half hour nap after work, online classes, then a 5 hour sleep, with a full of off/switch days would be easily possible for a lot of people out there, but probably not me. I think the solution will sadly have to be dropping the class xP