ED 101: Understanding Erectile Dysfunction & What’s Really Happening in Your Body

After three decades in medicine studying how the body responds to stress and challenge, I have learned that understanding the why behind what happens often reduces anxiety and helps people make smarter decisions about their health. When erectile dysfunction occurs, understanding what actually happens in your body—without overwhelming medical jargon—helps you see how remarkably complex and interconnected your body really is.

When Everything Works in Harmony

An erection involves far more than blood flow—your entire nervous, cardiovascular, hormonal, and psychological systems work together in precise coordination. Think of conducting an orchestra where every section needs to crescendo at exactly the right moment.

The remarkable sequence that happens in healthy erectile function looks like this:

• Your brain processes the moment: Whether through physical touch, visual stimuli, or thoughts, your brain evaluates safety, desire, and readiness. Unconsciously, your nervous system rapidly assesses whether conditions are right for vulnerability and intimacy.
• Your nervous system sends the signal: When your brain gives the green light, it sends messages down your spinal cord through the parasympathetic nervous system—your rest and digest system that governs relaxation and restoration (this is key).
• Blood vessels respond: The signal reaches tiny muscles in your penile arteries, telling them to relax. As these smooth muscles release their grip, the penile arteries widen dramatically—research shows that penile blood flow can increase up to 20 to 40 times during erection compared to baseline levels.
• The hydraulic system engages: s the erectile chambers fill, expanding tissue compresses the subtunical venules, reducing venous outflow and creating the hydraulic “venous occlusive” mechanism that maintains rigidity. This creates a hydraulic lock, keeping the blood there, which is what allows rigidity to be maintained. It is truly brilliant engineering!
• Hormones support the process: Testosterone provides the drive and keeps the  tissue responsive. Nitric oxide—a molecule your blood vessels produce—acts like a chemical key that unlocks the smooth muscle relaxation.

When all these elements work together, like an orchestra in harmony, erections happen naturally and effortlessly. But when any section of this orchestra is out of tune, the whole performance can suffer.

When the Music Stops: What Can Go Wrong

From a resilience perspective, ED often represents your body’s way of saying that one or more systems are operating under stress or have exceeded their adaptive capacity. 

Let’s explore the main categories:

Vascular Causes: The Plumbing System

Your cardiovascular system is the foundation of erectile function. Conditions that affect blood flow anywhere in your body often show up in sexual function first, because the penile arteries are smaller and more sensitive than others.

• Atherosclerosis (artery hardening): When cholesterol, inflammation, and calcium build up in artery walls, they narrow the passages and reduce blood flow. What affects your heart arteries also affects the smaller penile arteries—often first.
• High blood pressure: Chronic hypertension damages the endothelium—the delicate lining of blood vessels—impairing their ability to relax and expand, a key contributor to erectile dysfunction.
• Diabetes:High blood sugar levels damage both blood vessels and nerves over time. Approximately half of all men with diabetes experience some degree of erectile dysfunction, reflecting combined vascular and neurological damage associated with chronic hyperglycemia.
• Smoking:Nicotine constricts blood vessels, while the chemicals in cigarettes damage the arterial lining. Many men notice improvement in erectile function within weeks of quitting.

Neurological Causes: The Wiring System

Your nervous system is the communication network that carries signals between your brain and your body. Damage anywhere along this pathway can disrupt erectile function.

• Spinal cord injuries: Since the nerves controlling erection travel through the spinal cord, injuries in the lower back can interrupt these signals.
• Multiple sclerosis: This condition affects the protective covering of nerves, potentially disrupting the signals needed for erection.
• Pelvic surgery: Procedures involving the prostate, bladder, or rectum can sometimes damage the delicate nerves responsible for erectile function.
• Diabetic neuropathy: Beyond blood vessel damage, diabetes can also harm the nerves that control erectile function.

Hormonal Causes: The Chemical Messengers

Your endocrine system produces hormones that regulate sexual desire, energy, and tissue health. Disruptions here can significantly impact erectile function.

• How testosterone: While testosterone levels naturally decline with age, significant drops can reduce libido and make erections more difficult to achieve and maintain.
• Thyroid disorders: Both overactive and underactive thyroid can affect sexual function through their impact on energy, mood, and vascular health.
• High prolactin:This hormone, when elevated, can suppress testosterone and reduce sexual interest and function.

Psychological and Stress Related Causes: The Mind-Body Connection

This is where my expertise in stress and resilience becomes particularly relevant. Your mental and emotional state profoundly impacts sexual function through multiple pathways.

• Performance anxiety: Once you’ve experienced ED, the fear of it happening again can create a cycle where anxiety actually causes the very problem you’re worried about.
• Chronic stress: Elevated cortisol constricts blood vessels, suppresses testosterone synthesis, and sustains sympathetic “fight-or-flight” activation—the physiological opposite of the parasympathetic state required for erection.
• Depression: Clinical depression affects neurotransmitters like serotonin and dopamine that influence both mood and sexual function. Many antidepressants can also impact sexual performance as a side effect.
• Relationship stress: Unresolved conflicts, communication problems, or emotional distance can prevent the psychological relaxation necessary for healthy sexual function.

Medication Related Causes: Unintended Consequences

Many common medications can interfere with erectile function, often through multiple mechanisms:

• Blood pressure medications: Some types can reduce blood flow or interfere with the nervous system signals needed for erection.
• Antidepressants: Selective Serotonin Reuptake Inhibitors (SSRI’s) and other antidepressants commonly affect sexual function by altering neurotransmitter levels.
• Antihistamines: These can have anti-cholinergic effects that interfere with the nervous system pathways involved in erection.
• Prostate medications: Some treatments for enlarged prostate can impact sexual function.

Lifestyle Factors: The Foundations for Resilience

From a resilience standpoint, these are often the most modifiable factors:

• Sleep deprivation: Poor sleep disrupts hormone production, increases stress hormones and inflammation, and impairs recovery from daily stressors.
• Sedentary lifestyle: Regular physical activity is crucial for maintaining healthy blood flow and hormone balance.
• Poor nutrition: Diets high in processed foods and low in nutrients contribute to inflammation, poor blood sugar control, and vascular problems.
• Excessive alcohol: While small amounts might reduce inhibitions, regular heavy drinking can damage nerves, reduce testosterone, and impair blood flow.
• Obesity: Excess weight contributes to diabetes, cardiovascular disease, low testosterone, and inflammation—all risk factors for ED.

The Interconnected Web: Why Multiple Factors are Usually Involved

What I find most important for men to understand is that ED rarely has just one cause. More often, it’s the result of multiple factors that compound each other. A man might have slightly elevated blood pressure, moderate stress, poor sleep, and be taking a medication that affects sexual function. Individually, none of these might cause problems, but together they can overwhelm his body’s adaptive capacity.

This is actually good news, because it means that addressing several factors simultaneously—even small improvements in each—can often restore function more effectively than trying to find and fix the “one” problem.

Your Body’s Remarkable Capacity for Recovery

Here’s what gives me hope in working with men experiencing ED: your body wants to work properly. When we remove barriers, reduce stressors, and support the systems involved in sexual function, recovery often happens naturally.

I’ve seen men restore erectile function by improving their sleep, managing stress more effectively, adjusting medications, or addressing underlying health conditions. The key is taking a comprehensive approach that honors the interconnected nature of your body’s systems.

Understanding what’s happening in your body isn’t just academic—it’s empowering. When you know that ED often reflects broader health patterns, you can make informed decisions about addressing not just the symptom, but the underlying factors that contribute to it.

Your body has carried you through decades of challenges with remarkable resilience. Now it’s giving you information about what it needs to function optimally. Listening to that information isn’t failure—it’s wisdom.

Dr. Eva Selhub is Chief Medical Affairs Officer at ForHumanity.co, a former Harvard faculty physician, and internationally recognized expert in resilience and mind-body medicine. She is the author of several books on stress, resilience, and optimal health.