We saw in our last article that testosterone is very important for men’s health, and that for optimal health, abnormally low T levels ought to be corrected either through lifestyle changes – diet, exercise, sleep – or through supplementation. In this article, we’ll discuss the importance of more sleep for higher testosterone.
Less sleep associated with lower testosterone
In older men, age 64 to 74, testosterone levels were highly correlated to the amount of sleep they got on the previous night. The correlation coefficient, r=0.842, which is high. See chart below.
The difference in T levels among the men was large, ranging over several hundred ng/dL, so this is not a small effect by any means.
The question is, how much of this correlation is due to ill health and/or aging? Older people notably sleep less, and other health problems can both make that worse and also decrease testosterone. So what we want to know is whether sleep directly affects testosterone levels.
Sleep restriction decreases testosterone
The answer is, yes, sleep directly affects testosterone.
In young healthy men, decreasing the amount of sleep from 8 to 5 hours a night, for 8 nights, decreased testosterone from 10 to 15%.
Symptoms and signs of androgen deficiency include low energy, reduced libido, poor concentration, and increased sleepiness, all of which may be produced by sleep deprivation in healthy individuals.
Sleep restriction also increases insulin resistance, and since as we saw in the previous article that insulin resistance and testosterone levels are intertwined, that makes sense.
Shift work is associated with ill health
Shift work, which is working hours other than during the daytime, such as swing shift (3:00 PM to 11:00 PM), or night (graveyard) shift (11:00 PM to 7:00 AM) is associated with ill health, including heart disease and cancer.
Given the above correlations between sleep and testosterone, we could also expect to find that shift work would decrease testosterone. Shift work is associated with elevated cortisol levels and higher BMI, and that would likely mean a decrease in testosterone.
Get some sleep
If you have low testosterone, one of the first things you should examine is whether you get enough sleep, and that applies to both young and older men.
If you do shift work, consider changing to another job, or at least another shift.