You get a huge epinephrine and adrenaline dump into your system to activate the fight or flight response. If you can try breathing and focusing, sometimes you can overcome it. For me, mostly not. Getting on in the morning is because you are coming out of a low hormone phase and the two items mentioned above are activated to get you awake/alert cycle started.

Look for and listen to "Huberman Lab" podcast. That guy has a wealth of science based information in many areas of how our bodies work.