Many men begin to notice subtle but persistent changes after the age of 40. Energy levels dip, muscle becomes harder to maintain, recovery slows, mood can flatten, and sexual function may not feel as reliable as it once did. While these changes are often dismissed as “normal ageing”, the reality is more nuanced. Hormonal shifts, particularly in testosterone, interact closely with cardiovascular health, metabolism, mental wellbeing and erectile function.

Understanding what is normal, what is modifiable, and when medical input is appropriate can make a meaningful difference to long-term health and quality of life.

Testosterone and Ageing: What Actually Changes?

Testosterone levels do decline with age, typically by around 1% per year from the late 30s or early 40s onwards. This decline is gradual rather than sudden and varies significantly between individuals. Genetics, body composition, sleep quality, stress, alcohol intake, chronic illness and medication use all influence the rate of change.

Testosterone is produced primarily in the testes, stimulated by signals from the brain via luteinising hormone (LH). With age, this signalling pathway becomes less efficient, and the testes themselves respond less robustly. At the same time, levels of sex hormone-binding globulin (SHBG) often rise, meaning less free or bioavailable testosterone is available to act on tissues, even if total testosterone appears “normal” on paper.

This is why symptoms often correlate more closely with free or bioavailable testosterone than total testosterone alone.

Recognising Symptoms That Matter

Low or declining testosterone can present in several overlapping ways. Physical symptoms may include persistent fatigue, reduced muscle mass and strength, increased abdominal fat, slower recovery from exercise and reduced bone density. Many men also notice changes in libido, fewer morning erections, weaker erections or changes in sexual satisfaction.

Mental and emotional changes are common but under-recognised. These can include low mood, irritability, reduced motivation, brain fog and difficulty concentrating. Because these symptoms overlap with stress, sleep deprivation and midlife pressures, testosterone issues are often missed without testing.

Importantly, not every man with symptoms has low testosterone, and not every man with lower levels feels unwell. Context matters.

Testosterone, Heart Health and Metabolic Risk

Testosterone plays a meaningful role in cardiovascular and metabolic health. Lower levels are commonly associated with increased visceral fat, insulin resistance, chronic inflammation and adverse lipid profiles. Over time, this combination increases the risk of coronary artery disease, stroke and type 2 diabetes.

Men with lower testosterone often show higher LDL cholesterol, lower HDL cholesterol and raised triglycerides. Vascular function can also suffer, as testosterone supports nitric oxide production, which helps blood vessels relax and maintain healthy blood pressure.

Lifestyle remains powerful. Regular aerobic activity, resistance training, maintaining a healthy waist circumference, and following a Mediterranean-style diet have consistently been shown to improve cardiovascular markers and reduce metabolic risk.

Erectile Function: More Than a Hormone Issue

Erectile dysfunction (ED) becomes more common with age, but it is rarely caused by testosterone alone. Vascular health is central. Reduced blood flow, endothelial dysfunction and nerve signalling changes all contribute.

Low testosterone can reduce libido and worsen erection quality, but diabetes, hypertension, cardiovascular disease, pelvic surgery, neurological conditions, mental health and medication side effects are equally important contributors. This is why effective management focuses on the whole picture rather than a single hormone.

Where appropriate, treatments may include lifestyle changes, PDE5 inhibitors such as sildenafil or tadalafil, hormonal optimisation when deficiency is confirmed, and psychosexual counselling where stress or anxiety plays a role.

Cognitive Health, Mood and Motivation

Many men report subtle cognitive changes as they age, including slower recall, reduced mental sharpness and difficulty focusing. Research suggests that testosterone supports aspects of memory, executive function and mood regulation. Lower levels are often associated with low drive, mild depressive symptoms and reduced resilience to stress.

Poor sleep, chronic stress and elevated cortisol further suppress testosterone production, creating a feedback loop that affects mood, cognition and energy. Addressing sleep quality, stress management and physical activity is often as important as addressing hormone levels themselves.

Testosterone in the Wider Hormonal System

Testosterone does not act in isolation. It exists within a network that includes oestrogen, dihydrotestosterone (DHT), LH, follicle-stimulating hormone (FSH), thyroid hormones, cortisol, growth hormone and IGF-1. Imbalances elsewhere in this system can produce symptoms even when testosterone appears adequate.

For example, excessive conversion of testosterone to oestrogen can affect mood and libido, while high cortisol from chronic stress can blunt testosterone production entirely. This is why comprehensive assessment is more useful than isolated testing.

Proactive Lifestyle Strategies After 40

Midlife health responds well to consistent, realistic habits rather than extreme interventions. Adequate protein intake supports muscle mass and metabolic health. Strength training two to three times per week preserves muscle, bone density and insulin sensitivity. Regular walking and aerobic exercise support heart health and waist control.

Sleep is critical. Less than five hours per night can reduce testosterone by up to 10–15% within a week. Managing alcohol intake, quitting smoking, staying hydrated and addressing snoring or sleep apnoea all protect hormonal balance.

Stress management is not optional. Even short daily practices such as breath work, walking outdoors or structured downtime can reduce cortisol and support recovery.

When to Consider Medical Assessment

Medical assessment is appropriate when symptoms persist, worsen or interfere with quality of life. Accurate testing requires morning blood tests, ideally repeated, alongside a review of symptoms, medications and underlying health conditions.

Treatment decisions depend on the cause. Some men benefit from addressing sleep apnoea, weight, insulin resistance or medication effects alone. Others may require targeted hormonal treatment, always with careful monitoring of blood counts, prostate markers and cardiovascular risk.

The goal is not to chase youthful numbers, but to restore balance, function and wellbeing safely.

A Long-Term Perspective

Testosterone does decline with age, but how you experience that decline is heavily influenced by lifestyle, health status and early intervention. Men who take a proactive, informed approach often maintain energy, strength and sexual health well into later life.

Small, consistent changes compound. Regular health checks turn guesswork into clarity. Acting early allows you to adjust course rather than react to problems later.

Conclusion

Men’s health after 40 is not about fighting ageing; it is about understanding it. Testosterone plays a central role, but heart health, metabolism, sleep, stress and mental wellbeing are equally important. With the right information and support, most men can maintain a high quality of life through midlife and beyond.

If you are experiencing changes in energy, mood, sexual function or motivation after 40, a structured medical assessment can help clarify what is normal and what can be improved.

At Niva Medical Clinic, our doctors offer confidential men’s health consultations with evidence-based testing and personalised guidance.