Why am I so tired?

People’s bodies have different biorhythms. For some, refreshing sleep is in the morning. For others, it’s at night.

Or, you could be getting bipolar disorder. Needing less sleep is a symptom (but I think the chances of this are low).

Or you might only think you feel more awake later, but in fact you are equally sleepy.

Or, a theory to be named later.

I am basically a nocturnal human being. No matter how much sleep I get, if it’s at night and I must wake up early in the morning, I’m still tired. Now that I sleep during the day and wake up at night, if I’ve had enough sleep I feel much more awake. Maybe you’re just on the wrong sleep schedule for you.

Caffeine keeps you up, but makes it harder to get good sleep. Lots of coffee may just make you feel more restless

Do a little research about the term Circadian Rhythms.

There are places doing specialized research and studies and you may find something helpful for your personal situation.

If you can access it, and further to @Buttonstc response, you might want try taking the test at http://www.bbc.co.uk/science/humanbody/sleep/crt/…it might help. I dunno.