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Benchmark Proactive Health - March 6, 2026
Takeaways from content we’ve enjoyed & other timely topics
Testosterone plays an often underappreciated role in both men’s and women’s health. In men, the testes manufacture about 4–9 mg daily, a tiny amount with a major health impact. Women produce about 20 times less, though interestingly, this is still more than their daily estrogen production. Testosterone regulates muscle and bone strength, energy, mood, metabolism, and sexual function. In women, it also serves as a key building block for estrogen production.
Testosterone follows a daily rhythm. Levels typically peak in the morning and change throughout the day, as it is released in pulses by the brain’s hormonal control system. Much of this production occurs during sleep, particularly during deeper stages. When sleep is shortened or disrupted, testosterone can fall quickly. In one study, restricting healthy young men to five hours of sleep per night for one week reduced testosterone levels by 10–15%, similar to the decline normally seen over a decade of aging.
Measuring testosterone levels can be valuable, particularly because symptoms are often under-recognized. Unlike hormones such as estrogen and progesterone, which fluctuate significantly across the menstrual cycle, testosterone is relatively stable from day to day. However, since levels change over the course of the day, testing should be done early in the morning and typically repeated when symptoms are present.
The total amount of testosterone circulating in the blood does not tell the whole story. Only about 1–3% of testosterone is “free,” meaning immediately available to cells. Most is bound to proteins such as albumin (bound loosely) and sex hormone–binding globulin (SHBG) (bound tightly), which regulate how much hormone is accessible to tissues. As a result, someone can have “normal” total testosterone levels but still have low usable testosterone, depending on how much is bound. Therefore, total testosterone is often interpreted alongside SHBG, albumin, and free testosterone.
Testosterone levels gradually decline with age. In men, levels typically begin decreasing in the mid-30s at about 1–2% per year. In women, testosterone gradually declines, typically beginning in her 30s or 40s, and particularly after menopause.
Low testosterone can arise from a range of causes, including problems affecting the testes or ovaries, disruptions in the brain’s hormonal signaling centers, certain medications, obesity, and metabolic disorders. However, while low levels become more common with age, only a very small percentage of men over 40 have both low testosterone and significant symptoms; lab results alone do not always explain how someone feels.
Testosterone plays an important role in our metabolic health. Healthy testosterone signaling supports muscle maintenance, bone strength, insulin sensitivity, and fat metabolism. Lower levels of testosterone are associated with insulin resistance, increased visceral fat, metabolic syndrome, and higher cardiometabolic risk. Declining testosterone can be an early signal that metabolic health is under strain.
Lifestyle factors can influence testosterone levels more than many people realize. Because production is closely linked to sleep, chronic sleep deprivation can suppress testosterone. Body composition also plays a role: excess visceral fat can reduce testosterone levels through hormonal and inflammatory pathways. Physical activity, particularly resistance training, helps maintain muscle mass and supports healthier hormonal signaling, while chronic energy deficits or extreme endurance training can suppress it. Other lifestyle factors that can lower testosterone include chronic stress, moderate to heavy alcohol consumption, and endocrine disrupting chemicals (such as phthalates and BPA) can reduce testosterone levels.
For men, testosterone replacement therapy may be considered when blood tests confirm low levels on two separate morning measurements, along with symptoms such as reduced sexual desire, fatigue, decreased muscle mass, or mood changes. When appropriately prescribed, treatment can improve sexual function, increase muscle and bone strength, correct anemia, and provide improvements in energy and mood.
For women, the primary evidence-based use of testosterone therapy is for treatment of persistent, significantly reduced sexual desire in postmenopausal women. As women’s health and hormonal treatments begin to receive more attention and investment (at long last), we expect to see testosterone treatment options and use cases evolve and expand.
Testosterone therapy can be powerful in the right instances, but is not appropriate for everyone. There are specific contraindications to testosterone therapy. It should always be evaluated and managed on an individual basis with a medical professional.
Highlights from Benchmark’s community
Members recommended two books this month with similar themes of attention, focus and how to reclaim our time. Stolen Focus by Johann Hari argues that our culture of information overload, digital distraction, and the pressure to multi-task, is undermining our ability to concentrate and think deeply. Meditations for Mortals by Oliver Burkeman reminds us that life is finite, and the list of important tasks can be endless. Rather than feeling overwhelmed, we should accept the reality of our constraints as mortals, and embrace "imperfectionism." Instead of seeking hacks to “do it all” we should focus on what we deem truly worthy of our energy.
In the spirit of reclaiming our time, we’re seeing efforts to combat the distraction of digital devices. Friends are resolving to see “sky before screens,” or touch “grass before glass,” i.e., connecting with nature before being pulled into the smartphone vortex. A number of products are also helping to reduce digital distraction. Brick is a device that temporarily disables distracting app notifications on your phone. You can even buy a lockable cabinet designed to keep your phone away from you.
Speaking of rewinding the digital clock to simpler times, if you miss the days when phones were used to connect with other humans, for actual conversations...the landline is making a comeback, twisted cord and all. Tincan is a retro landline for kids, that helps reduce the gravitational pull toward smartphones, and relieves parents of their roles as text message intermediaries. Nancy has it in her house, and can attest that overhearing kids’ phone conversations is priceless.
Tincan wi-fi connected landline phone for kids
If you’re accustomed to sleeping 6 hours a night and feeling fine, you may be misjudging your true fatigue. Scott shared a powerful study on the cumulative cost of additional wakefulness. Subjects were limited to 4, 6, or 8 hours of sleep a night for 14 days, and tested on cognitive performance. The 4h group had the greatest performance deficit, followed by the 6h group, and these deficits compounded with each day of restricted sleep. After two weeks, the 6h group showed cognitive impairment comparable to 24 hours of total sleep deprivation, and the 4h group to 48 hours.
The most shocking part though, was that after a few days of sleep restriction, the subjects didn’t report feeling any more tired, and the 4h group didn’t feel any more tired than the 6h group even though their performance indicated otherwise. It seems that the subjects’ perception of fatigue was also impaired. So even if you think you’re performing just fine on 6 hours of sleep, you may have just lost your ability to judge it. We are human after all, and sleep is non-negotiable.
The latest updates from Benchmark HQ
We're now located at: 3325 Harvester Road, Unit 5 in Burlington. We fully renovated the space, and we hope you'll love it as much as we do.
Take a quick tour here, with some finishing touches still to come.
NOTE: This newsletter is informational only; it is not medical advice. We have no stake in the products or brands we highlight here.
