Honestly, that could be so many things... diet, vitamin deficiency, etc. But, if you think all that’s good, you might want to get some bloodwork done to see if anything can be done about it. It could be something like iron deficiency anemia, which makes you feel tired and shitty and lethargic all the time. There’s a small chance that it could be something more serious as well; certain diseases, such as certain strains of hepatitis, can cause that feeling that you can’t stay awake.

Anyways. My point is, it could be anything. If it’s significantly affecting your quality of life, you should get it checked out so that maybe it can be treated. Good luck!