That’s not really normal. Off the top of my head, in order from most likely to least, here’s a list of things to check. Unfortunately, all of them cost money.
Carbon Monoxide detector. Put the batteries in outdoors before you set it up in your house: some require calibration in clear air first. Follow instructions.
Schedule a MD appointment to discuss this. Or at least monitor your heart rate while you’re asleep to see whether it might be sleep apnea. You might also ask about getting tested for ADHD.
Check for black mold or water leaks, probably requires a plumber, or home inspection, or your own testing hardware.
Can you change your diet to see if it’s anything you’re allergic to, like nuts or rat poison? Do you make your own food?
A Geiger counter works wonders to see if anyone’s stored unprotected fissile material in your home, like that wacko who disassembled smoke detectors.