Low libido: when the brain is the issue

Low libido in men is rarely just a testosterone issue. Here is how the brain, hormones, mood, and everyday habits interact to shape sex drive, and what actually helps when it stays low.

The relationship

Libido is your level of sexual desire or interest in sex. Low libido means that your usual interest in sex has dropped for weeks or months, in a way that feels out of character and creates worry, frustration, or relationship strain. Clinicians often call this “hypoactive sexual desire,” which is a long-lasting lack of sexual interest that you find distressing, not just different from some average.

Sex drive in men is shaped by a tight partnership between body and brain. Testosterone, the main male sex hormone, supplies biological “energy” for desire, but your brain’s reward and mood systems decide how motivated you feel to use that energy. Large population studies show that stress, depression, relationship conflict, chronic illness, and certain medications can all reduce sexual desire even when testosterone levels are in the normal range.^[1],[2] In other words, low libido is often a brain-and-life problem as much as a hormone problem.

Low libido is also common in men. Surveys from multiple countries suggest that 15–25% of men report reduced desire at some point, and rates are higher in men with depression, diabetes, or cardiovascular disease.^[1],[3] Yet many men never bring it up with a clinician, often from embarrassment or the belief that sex drive is supposed to fade with age. That silence can delay diagnosis of issues like low testosterone, untreated depression, or early heart disease that are very treatable when caught early.

How it works

Low libido in men is not caused by a single switch turning off. Desire is the output of several overlapping systems: brain reward circuits that generate “wanting,” hormone signals that set your baseline drive, mood and stress systems that can slam on the brakes, and everyday habits that shape energy and attention. When enough of these tilt in the wrong direction, sexual interest drops.

Neuroscientists describe libido as a motivated behavior, similar to hunger or curiosity. The brain constantly weighs signals about safety, energy, connection, and reward value. If work stress is high, mood is low, sleep is poor, or sex has become linked with conflict or failure, the system quietly de-prioritizes sex — even if your testosterone looks fine on paper.^[2]

Brain reward and motivation circuits

Dopamine is a neurotransmitter, a chemical messenger in the brain, that tracks reward and drives motivation; norepinephrine is a related chemical that supports alertness and focus. Imaging and clinical studies show that reduced activation in dopamine-rich areas such as the ventral striatum and prefrontal cortex is linked to low sexual desire in men, especially when depression or chronic stress are present.^[2],[4]

Testosterone and other hormones

Testosterone sets a man’s baseline capacity for libido, but low libido can occur even with normal levels, and many men with low testosterone still report normal desire.^[3] Meta analyses indicate that symptomatic men with total testosterone below 350 ng/dL (≈12 nmol/L) are most likely to benefit from testosterone replacement therapy (TRT); if total testosterone is borderline, free testosterone below 100 pg/mL (≈10 ng/dL) supports a diagnosis of hypogonadism, which means the testes are not making enough testosterone for the body’s needs.^,[5]

Stress, mood, and the threat system

The stress response system, often called the HPA axis (hypothalamic–pituitary–adrenal axis), controls cortisol, the main stress hormone; chronic activation of this system is linked to reduced sexual desire and higher rates of depression and anxiety in men.^[2],[6] When the brain is locked in “threat mode,” it shifts resources toward survival and away from exploratory behaviors like sex, even when hormones and blood flow are technically adequate.

Medications, substances, and attention

Several common medications, especially selective serotonin reuptake inhibitors (SSRIs, a class of antidepressants), some blood pressure drugs, and chronic opioid pain medicines, can blunt dopamine signaling and lower libido in men.^[4],[7] Heavy alcohol use, some recreational drugs, and constant high-intensity screen or pornography use can also reshape what the brain finds sexually rewarding, shifting attention away from real-life intimacy toward more intense or novel stimulation.

Conditions linked to it

Low libido can be an early warning light for other health issues. Sometimes the cause is straightforward, like a new medication with known sexual side effects. Often it is a cluster of factors — mild depression, poor sleep, weight gain, and creeping blood pressure — that together sap sexual interest long before a man feels sick in other ways.^[1],[3]

Mood disorders are a major connection. Men with depression or significant anxiety have higher rates of low sexual desire, even after adjusting for age and testosterone levels.^[2],[4] Sometimes the depression comes first and flattens libido; sometimes persistent sexual problems feed hopelessness and withdrawal.

Metabolic and cardiovascular diseases also matter. Diabetes, obesity, and cardiovascular disease are all associated with lower libido and more global sexual dysfunction in men, likely through a mix of reduced blood flow, nerve changes, low-grade inflammation, and hormonal shifts.^[3],[6] Low libido in a man with emerging erectile issues can be an early sign of vascular disease and deserves a heart-health check.

Other medical contributors include sleep disorders such as obstructive sleep apnea (a condition where breathing repeatedly stops during sleep), high prolactin levels (a hormone that, when elevated, can suppress testosterone and desire), and thyroid problems that affect energy and mood. Chronic pain and the drugs used to treat it, especially opioids, can also dampen sex drive over time.^[5],[7]

• Mental health: depression, anxiety disorders, chronic stress, and trauma histories
• Metabolic and heart health: type 2 diabetes, obesity, high blood pressure, cardiovascular disease
• Hormonal: hypogonadism, high prolactin, thyroid disorders
• Sleep: obstructive sleep apnea, chronic sleep deprivation
• Medications and substances: SSRIs, some blood pressure medicines, opioids, heavy alcohol or drug use

Limitations: most of these links come from observational studies, which can show association but not always clear cause-and-effect. In practice, clinicians look for clusters of problems — for example, low libido plus fatigue, central weight gain, and snoring — and then test and treat the likely drivers.

Symptoms and signals

Every man’s baseline sex drive is different. The key signal of low libido is not how often you want sex compared with your friends or what you see online, but how far you have drifted from your own normal pattern — and how much that change bothers you or your partner.

• Much fewer sexual thoughts or fantasies than you used to have
• Going days or weeks without any interest in sex, when that used to feel unusual
• Rarely or never starting sex with a partner, even when the opportunity is there
• Feeling indifferent when a partner initiates, or going along out of duty rather than desire
• Having trouble feeling mentally “switched on,” even if you can get an erection
• Sex feeling like work or another item on the to-do list rather than something to look forward to
• Finding it harder to become aroused by things that used to do it for you (touch, flirting, specific fantasies)
• A sharp drop in libido after a change in medication, illness, major stressor, or conflict in your relationship

Red flags that mean you should seek medical or mental health care quickly include suicidal thoughts, a sudden collapse in libido over days or weeks with no clear trigger, new breast tenderness or enlargement, severe fatigue, or unintentional weight loss. These can signal serious depression, major hormonal problems, or other medical conditions that should not wait.

What to do about it

The good news is that low libido in men is usually understandable and often reversible once you look at the whole system: brain, body, and daily life. The most effective plans follow a clear sequence — test, tune the foundations, then consider targeted therapies if needed — rather than jumping straight to pills or blaming age.

1. Step 1: Get a proper evaluation

   Start with a clinician who is comfortable talking about sexual health, such as a primary care doctor, urologist, or endocrinologist. A good evaluation covers your medical history, medications and supplements, sleep, mood, energy, substance use, and the context of your relationship and sexual life. Expect questions about when low libido started, whether it fluctuates, and how it relates to erections and orgasm.

   Basic lab work for a man with persistent low libido usually includes two separate early-morning total testosterone measurements, free testosterone if the total is borderline, prolactin, thyroid-stimulating hormone (TSH, which checks thyroid function), fasting glucose or HbA1c (a marker of average blood sugar), and sometimes cholesterol and liver tests.^,[5] As noted above, total testosterone below about 350 ng/dL (≈12 nmol/L) or free testosterone below about 100 pg/mL (≈10 ng/dL) in a symptomatic man supports hypogonadism and makes TRT more likely to help.^,[5] Screening for depression, anxiety, and sleep apnea is also important, because treating these often improves libido on its own.^[4],[6]

2. Step 2: Fix the foundations and use targeted treatments

   Once major medical causes have been ruled in or out, the next move is to tune the basics that most strongly affect male sex drive:

   • Sleep and recovery. Aim for 7–9 hours of consistent sleep. Poor sleep lowers testosterone and raises cortisol, both of which can blunt libido. Treating obstructive sleep apnea, when present, can improve testosterone and sexual function over time.^[6]
   • Stress and mood. Cognitive behavioral therapy (a form of structured talk therapy that targets unhelpful thoughts and behaviors), regular aerobic exercise, and resistance training all have evidence for improving depression, anxiety, and sexual function in men.^[4] Even 150 minutes per week of moderate exercise is linked to better erectile function and higher reported desire.
   • Relationship and sexual script. Honest conversations about pressure, resentment, or routine can be uncomfortable but often key. When sex has become linked with performance anxiety or repeated conflict, low libido is a logical response. Short-term couples or sex therapy can help men rewrite the “script” so sex feels safer and more rewarding.
   • Medication review. If libido dropped after starting an SSRI, blood pressure pill, or chronic pain medication, ask your prescriber whether dose changes or alternatives with fewer sexual side effects are possible. For example, switching some men from an SSRI to bupropion, which has more dopaminergic and noradrenergic action, can improve libido, though this must be done under medical supervision.^[7] Never stop psychiatric or heart medications abruptly on your own.
   • Hormonal and erectile treatments. For men with confirmed hypogonadism and bothersome low libido, TRT can improve desire, energy, and erectile function, though it requires careful monitoring of blood counts, prostate, and cardiovascular risk.^,[5] If erections are weak, addressing cardiovascular risk factors and using PDE5 inhibitors (drugs like sildenafil that improve penile blood flow) can indirectly support libido by making sex feel more possible and less stressful.^[3]
   • Brain-focused therapies for stubborn low libido. After sleep, stress, hormones, mood, and erection issues are addressed, some men with persistent low libido may benefit from treatments that directly nudge dopamine and norepinephrine. This can include structured “behavioral activation” plans that schedule rewarding, mastery-building activities, as well as, in selected cases, medications like bremelanotide or off-label flibanserin, used only under specialist guidance. Bremelanotide is a melanocortin receptor agonist, a drug that acts on brain receptors involved in sexual arousal, and early studies in men suggest it may increase desire in some cases; flibanserin affects serotonin, dopamine, and norepinephrine balance, though robust data in men are limited and it is not formally approved for male use.

   Limitations: evidence for dopamine- and norepinephrine-based drugs in men is still emerging, often from small or early-phase trials, and these medications can have side effects like nausea, changes in blood pressure, or interactions with alcohol. They should be considered only after more established drivers of low libido have been thoroughly addressed.

3. Step 3: Monitor, adjust, and stay curious

   Libido rarely snaps back overnight, especially if it took months or years to slide. Give any set of changes — better sleep, adjusted meds, exercise, therapy, or TRT — at least 8–12 weeks before judging the impact on sex drive, unless side effects demand an earlier change. During that time, track a few simple numbers each week, such as desire on a 0–10 scale, number of satisfying sexual encounters (solo or partnered), mood, and energy.

   Regular check-ins with your clinician allow fine-tuning: adjusting TRT doses if used, trying a different antidepressant, adding therapy, or tapering unnecessary medications. Bringing your partner into some of these visits can help align expectations and reduce the silent pressure that often crushes desire. Curiosity and experimentation — trying new contexts for intimacy rather than chasing performance — are often the final ingredients in getting a healthier libido to actually show up in bed.

Myth vs Fact

• Myth: Low libido in men is always caused by low testosterone.
  Fact: Many men with low libido have normal testosterone, and stress, mood, medications, and relationships are often bigger drivers.
• Myth: If you can get an erection, your sex drive must be fine.
  Fact: Erections are about blood flow and nerve function; libido is about wanting. You can have strong erections with low desire, or high desire with unreliable erections.
• Myth: Getting older automatically kills male sex drive.
  Fact: Desire tends to decline gradually with age, but many men maintain strong libido into their 60s and 70s, especially when they protect sleep, heart health, and relationships.
• Myth: Porn is the only reason young men have low libido.
  Fact: Heavy, compulsive pornography use can contribute for some men, but mood issues, stress, poor sleep, and medical problems also play major roles.
• Myth: “Real men” should want sex all the time.
  Fact: Healthy libido fluctuates with life. What matters is whether your desire matches your own values and goals, not a stereotype.

Bottom line

Low libido in men is common, understandable, and usually fixable. It reflects an interaction between brain chemistry, hormones, health conditions, medications, stress, and relationships, not a simple failure of masculinity or willpower. When you take it seriously, get evaluated, and work through a stepwise plan — from sleep and mood to hormones and, in selected cases, brain-targeted therapies — you are not just improving sex; you are often improving long-term health and quality of life.

References

1. Laumann EO, Nicolosi A, Glasser DB, et al. Sexual problems among women and men aged 40-80 y: prevalence and correlates identified in the Global Study of Sexual Attitudes and Behaviors. International journal of impotence research. 2005;17:39-57. PMID: 15215881
2. Bancroft J, Janssen E. The dual control model of male sexual response: a theoretical approach to centrally mediated erectile dysfunction. Neuroscience and biobehavioral reviews. 2000;24:571-9. PMID: 10880822
3. Corona G, Rastrelli G, Maseroli E, et al. Sexual function of the ageing male. Best practice & research. Clinical endocrinology & metabolism. 2013;27:581-601. PMID: 24054932
4. Atlantis E, Sullivan T. Bidirectional association between depression and sexual dysfunction: a systematic review and meta-analysis. The journal of sexual medicine. 2012;9:1497-507. PMID: 22462756
5. Mulhall JP, Trost LW, Brannigan RE, et al. Evaluation and Management of Testosterone Deficiency: AUA Guideline. The Journal of urology. 2018;200:423-432. PMID: 29601923
6. Penev PD. Association between sleep and morning testosterone levels in older men. Sleep. 2007;30:427-32. PMID: 17520786
7. Serretti A, Chiesa A. Treatment-emergent sexual dysfunction related to antidepressants: a meta-analysis. Journal of clinical psychopharmacology. 2009;29:259-66. PMID: 19440080