It seems to me that you suspect that you may have sleep apnea. The best way to ascertain that is to get a sleep study done. Sleep apnea can be treated. Left untreated, it can be dangerous for you and others (see gloaming). If nothing else, a sleep study would ease your stress about the issue.

I do not live in the USA so I can't speak about costs of getting a referral, having a test or getting a machine.

Are you asking because you think you have sleep apnea or are these general questions about sleep apnea?

Adrenaline is the product from the adrenal glands that spurs the body into fight-or-flight mode. It makes you sweat more easily, makes your liver release more glucose into the blood to help you to use the large muscles for flight or for defense, and it makes your irises dilate so that you can see better (both in dimmer light if needs be but also in higher resolution due to the increased aperture, so finer details at a distance are seen this way). It even causes piloerection, or the standing-up of hairs on your body....so that you might appear to be larger than you really are. A bear doesn't like attacking another bear, if you follow.

The higher heart rate makes more glucose available at any part of the downstream flow from the heart, but it also helps to flush away the byproduct of urgent and sustained metabolism, that being carbon dioxide.

Adrenaline also helps with alertness, improved reflexes, focus, and with increased breathing rate. Think of all your body must do suddenly, urgently, quickly, with great force, to ensure your survival or to minimize damage you'll sustain if you're slower than your predator. As you might surmise, all of these effects serve to make you more potent and energetic, not to make you get sleepy, warm and cozy, and to nod off.

So, yes.