In the study, published in the Journal of the American Medical Association, researchers compared testosterone levels in a group of 10 healthy young men after a week of normal sleep and a week of sleep loss.
In the first week, the participants slept eight hours each night at home. Then they had three nights of 10-hour sleep and eight nights of 5-hour sleep in a sleep laboratory.
The results showed that testosterone levels decreased by 10%-15% after the week of sleep loss compared with their rested states. This decrease in testosterone levels was also associated with a loss of vigor among the participants.
Researchers say about 15% of adult workers in the U.S. get five hours or less of sleep per night, and this study suggests this kind of prolonged sleep loss could have a negative consequence on testosterone and men's well-being.