Extra hour sleep raises testosterone level by 12 percent

Aging men’s testosterone decline is largely due to the fact that older men sleep less well than younger men. Endocrinologists at the National University of Singapore reached this conclusion after studying 531 Chinese men aged between 29 and 72. The researchers measured the amount of testosterone in the men’s blood in the mornings, and asked the men about their sex lives and their sleep.

Sleep is healthy. Sleep an hour longer and your fat percentage goes down by three percent. More sleep improves your memory. That men sleep less as they get older, and the worse the quality of their sleep the less testosterone they produce, are known facts. But to what extent do older men produce less testosterone because they are sleeping worse?

Men make less testosterone as they age simply because their health declines. The higher your blood sugar level, cholesterol, triglycerides and uric acid, the lower your testosterone level. For this reason the researchers selected a group of healthy men, “with no known existing or history of major medical illnesses such as cancer, hypertension, thyroid dysfunction, diabetes, osteoporotic fracture and cardiovascular events as well as major sleep disorders”.

That the subjects were unusually healthy is reflected in the table below. The reduction in testosterone level (TotalT) and in bio-available testosterone (BioT) with increasing age is modest. Bio-available testosterone is testosterone that is not attached to the protein SHBG. Testosterone that is attached to SHBG loses its anabolic and pro-sexual properties.


After forty the concentration of DHEA declines drastically, while the concentration of estradiol increases. The concentration of DHEA correlated with sex: the higher their DHEA level, the more often the men had sex. When looking at the data on sexual activity, it’s worth bearing in mind that Singaporean men always score very low in sex surveys. Must be cultural.

And yes, there was a relationship between testosterone and sleep.


Men who slept less than 4 hours in a 24-hour period had about 60 percent less TotalT and 55 percent less BioT than men who slept longer than 8 hours. Extrapolating this you arrive at the following estimate: one hour extra sleep raises your testosterone level by 12-15 percent.

“The significant association of sleep with androgen concentrations suggests that sleep might be a contributing factor in the etiology of men with low concentrations of androgen”, the endocrinologists conclude. “Therefore, in the management of men with low androgen concentrations, an evaluation of their sleep hygiene might add to the understanding the etiology of their hypogonadal state.”

Sleep, sex steroid hormones, sexual activities, and aging in Asian men.


This was a cross-sectional study to examine the different associations of age and sleep duration with sex steroid hormones and sexual activities in 531 Asian Chinese men aged between 29 and 72 years old. Sleep duration and sexual activities were evaluated through a self-administered questionnaire, and total testosterone (T), sex hormone-binding globulin (SHBG), estradiol (E2), and dehydroepiandrosterone sulfate (DHEAS) were measured by established immunoassay methods in a single blood sample collected between 8:00 and 11:00 am. Bioavailable T (BioT) was calculated using the Vermeulen formula. Age was a major determinant of sleep, sex steroid hormones, and sexual activities in men. BioT, DHEAS, coital frequency, masturbation, and sleep duration declined with age. On the other hand, SHBG and E2 increased with age. Sleep duration, independently of age, aerobic exercise, and body fat, was positively associated with T and BioT, but not with DHEAS, E2, or any of the sexual activities studied. Men who masturbated had higher levels of both T and BioT. DHEAS was significantly associated with coital frequency and desire for sex. The present study showed that besides age, sleep duration was associated with androgen concentrations in men, and thus the evaluation of sleep hygiene may be beneficial in the management of men with low androgen concentrations. DHEAS may be independently associated with some sexual functions in men.

PMID: 19684340 [PubMed – indexed for MEDLINE]

Source: http://www.ncbi.nlm.nih.gov/pubmed/19684340

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