Doctors will do that a lot - send you for blood tests and then give up once they come back normal. You need tests beyond your standard blood test. I have narcolepsy and no doctor ever brought up getting a sleep study, my parents actually did. You should push for a sleep study since this sounds like it could be a sleep disorder. If it’s not, you gotta advocate for yourself and push for answers because a healthy person does not feel that way after a good night of sleep.