Yeah, this will happen to Type 3 and sometimes Type 2B (but mostly 3). The reason can be cortisol and adrenalin can play a role (but not direct if the workout is in the morning).
What likely happens is that type 3 have a higher level of anxiety/mental stress. Anxiety sounds bad but in reality all it is, is the neurons firing too fast and the nervous system not being capable of slowing them down. This leans to overthinking: not being able to switch off the brain. And if it’s taken to extreme you can feel like you are losing control of your brain (bran is going too fast for you) which creates a panic attack.
Anyway, the main cause is not directly cortisol/adrenalin but it plays a role. Both speed up the neurons (put you in fight or flight mode). Serotonin and GABA are the neurotransmitters that “slow the neurons down”. Type 3 (and 2B when they are under a lot of stress) have low serotonin and/or GABA levels. This means that they have a harder time slowing down their brain once it’s sped up by adrenalin/cortisol. When that happens it will be really hard to get to sleep.
Z12 helps a bit because it increases GABA. But in your case it is likely more of a serotonin issue. 5HTP in the evening (250-500mg) would help in that regard (it provides the material to produce serotonin) as would glycine. Glycine is an amino acid that is a neural inhibitor (slows down the neurons). With clients like you I recommend 5-10g (depending on tolerance) of glycine post-workout and in the evening. It also have the benefit of lowering cortisol as well as increase mTor activation which can help build muscle.
Magnesium will also help as it can be a relaxant. But it needs to be magnesium glycinate to have maximum benefits.
I also use melissa infusions/herbal tea before bed.