Flooding is a really good description of what happens when I am overwhelmed by anxiety. My hearing loss increases, I can’t digest my food, I can become disoriented, and I lose coordination. Being teased as a child about being clumsy I better understand now what I experienced was such a high level of anxiety that getting my body to function took a back seat to the main event going on in my head.
Anxiety Overwhelms the Mind
In fact, during periods of intense anxiety, the brain is so overwhelmed with stress that it actually reduces the energy it provides other parts of your body. For example, digestion problems are very common with anxiety because anxiety actually causes the brain to pay less attention to the digestive system, causing it to go haywire. Anxiety also can cause certain parts of your brain to “turn off” in an effort to cope with stress.At its most chemical level, anxiety even affects the way neurotransmitters and hormones are produced, possibly leading to changes in the way you think and feel. When we talk about anxiety feeling overwhelming, it should be remember that it’s not just the way you feel. Anxiety really does have many overwhelming qualities, and can genuinely overwhelm your mind in many ways.
PTSD - Accepting, Coping, Thriving 
Flooding is a very good description and causes all sorts of knock-on effects. One for me is the production of adrenalin during the stressful stage and this creates severe adrenal fatigue leading to bouts of depression and exhaustion. The physical and emotional are very much connected.