Low testosterone in men is becoming a bigger problem with each passing decade. But what is the most significant cause of hypogonadism (the technical term for low testosterone)? It isn’t diet. It’s not environmental toxins or concussions, though they can affect a guy’s levels. It isn’t even drinking Bud Light. As you might surmise from the article's title, the most significant cause of low testosterone is circadian syndrome, a condition related to a disrupted circadian rhythm and sleep debt.



A new study shows how much of a problem this is for American men. In this article, I'll discuss some of the key findings and what we can do about them.



What is the prevalence of low testosterone?



The most current research shows that 20-50% of U.S. males have testosterone deficiency.Kwong JCC, Krakowsky Y, Grober E. Testosterone deficiency: a review and comparison of current guidelines. J Sex Med. (2019) 16:812–20. doi: 10.1016/j.jsxm.2019.03.262 The cutoff for clinically diagnosed testosterone deficiency is a blood level 300 ng/dl, which is where the data comes from, suggesting that up to half of American men have low testosterone. In comparison, optimal testosterone levels are between 800-1200 ng/dl. 



The problem is likely worse than that, as American men are less likely to get a checkup with their doctor than women, and even if they do, their doctors rarely check testosterone levels.



What happens to men with low testosterone?



Low testosterone leads to physical, mental, and sexual problems, including:




Physical Changes: increased body fat, decreased muscle mass and strength, fragile bones, hot flashes, fatigue, and increased cholesterol levels.Mulligan, T., Frick, M. F., Zuraw, Q. C., Stemhagen, A., & McWhirter, C. (2006). Prevalence of hypogonadism in males aged at least 45 years: the HIM study. International Journal of Clinical Practice, 60(7), 762-769.



Mental and Emotional Changes: changes in mood and mental capacity, including feelings of depression, irritability, trouble concentrating, and impaired memory.Shores, M. M., Sloan, K. L., Matsumoto, A. M., Moceri, V. M., Felker, B., & Kivlahan, D. R. (2012). Increased incidence of diagnosed depressive illness in hypogonadal older men. Archives of General Psychiatry, 61(2), 162-167.



Sexual Dysfunction: reduced sexual desire, fewer spontaneous erections, and infertility.Khera, M. (2016). Male hormones and men’s quality of life. Current Opinion in Urology, 26(2), 152-157.




In many cases, as men develop any of these health problems, the health problems themselves lead to a greater decline in testosterone, which worsens the problems, which further tanks testosterone. You must break the downward cycle, and sleep is likely the most important place to start.



What is Circadian Syndrome (CircS)?



According to the study authors,




CircS is primarily diagnosed based on hypertension, dyslipidemia, central obesity, diabetes, short sleep duration, and depression. Each of those symptoms is mainly governed by circadian rhythms, which are major regulators in almost every aspect of human health and metabolism.
Association between the prevalence rates of circadian syndrome and testosterone deficiency in US males: data from NHANES (2011–2016)



The Circadian Syndrome is diagnosed when a person has at least 4 of the following:




Central obesity: waist circumference ≥102 cm (40 inches);



High triglycerides (TG): TG ≥150 mg/dl or using TG-lowering drugs



Low high-density lipoprotein cholesterol: high-density lipoprotein cholesterol <40 mg/dl



High blood pressure: systolic blood pressure ≥130 mmHg or using antihypertensive drugs



High fasting glucose: fasting glucose ≥100 mg/dl or using anti-diabetic drugs



Short sleep duration: sleep duration <6 h/day on average



Depression: score ≥10 on the Patient Health Questionnaire (PHQ-9). You can access the PHQ-9 here.




How often do you hear a medical expert refer to high blood pressure,