Link Between HPA-Axis and the Sympathetic Nervous System
According to Harvard University, “The HPA axis relies on a series of hormonal signals to keep the sympathetic nervous system — the "gas pedal" — pressed down. If the brain continues to perceive something as dangerous, the hypothalamus releases corticotropin-releasing hormone (CRH), which travels to the pituitary gland, triggering the release of adrenocorticotropic hormone (ACTH). This hormone travels to the adrenal glands, prompting them to release cortisol. The body thus stays revved up and on high alert. When the threat passes, cortisol levels fall. The parasympathetic nervous system — the "brake" — then dampens the stress response.”
https://www.health.harvard.edu/staying-healthy/understanding-the-stress-response
It is important to note that under normal circumstances, when the stressful event is over, the gas pedal is lifted, the body shifts from sympathetic arousal to parasympathetic arousal, and cortisol levels drop back into normal range.
But, the return to “normal” physiology doesn’t happen in the case of PTSD.
Think of PTSD as stress that never ends because PTSD creates ongoing emotional and physical reactions such as:
1. Recurrent, involuntary, and intrusive distressing memories of the traumatic event(s).
2. Recurrent distressing dreams in which the content and/or affect of the dream are related to the traumatic event(s).
3. Dissociative reactions (e.g., flashbacks) in which the individual feels or acts as if the traumatic event(s) were recurring. (Such reactions may occur on a continuum, with the most extreme expression being a complete loss of awareness of present surroundings.)
4. Intense or prolonged psychological distress at exposure to internal or external cues that symbolize or resemble an aspect of the traumatic event(s).
5. Marked physiological reactions to internal or external cues that symbolize or resemble an aspect of the traumatic event(s). APA, 2013a
Sadly, the intrusive memories, dreams and flashbacks, the same emotional and physical reactions that characterize PTSD, paradoxically keep reactivating the chemical imbalances that caused PTSD in the first place. This reactivation process keeps the chemical imbalance of PTSD alive indefinitely.
How HPA-Axis Dysfunction Turns off Sexuality
To complicate matters, long-term stress creates hormonal shifts that put the brakes on sex drive and performance.
It stands to reason that when we get locked in overdrive, or sympathetic arousal, we are not in the mood to get down!
The shutdown of our sexual drive in the face of HPA-Axis/sympathetic arousal is adaptive, dating back to prehistoric times when we needed to react with lightning speed—to flee or fight dangerous prey.
When prehistoric man was on high-alert, fighting for survival, fists--and drawers--needed to stay up. It hardly made sense for prehistoric man to be thinking about dropping trou when a tiger was baring down on him! He needed to be thinking: How do I stand a better chance of not ending up in the bottom of the beast’s belly; should I flee or fight? As you can see, the automatic reaction to turn-off the sex drive in the face of stress is a built-in survival adaptation.
Once the tiger trotted off, the caveman’s physiology returned to normal allowing his body to switch from sympathetic arousal back to parasympathetic mode, which is also known as rest, digest and--get down--mode!
Winning the War on PTSD