We know that sleep issues can take a toll on a man's sex life, but now a new study shows another sex-related reason to get enough Zzzs.
The study, published in the American Journal of Epidemiology, shows an association between sleep disturbances and decreased sperm count.
Specifically, Danish researchers found that the men in the study who reported the most sleep disturbances had a 29 percent lower concentration of sperm in their semen, as well as a higher likelihood of having "fewer morphologically normal spermatozoa," compared with men who had lower scores on a sleep disturbance questionnaire.
The findings are based on semen and blood samples, as well as sleep disturbance questionnaire results, from 953 young men from Denmark who were being recruited for the military from 2008 to 2011.
"This study adds another suspect to the list of factors possibly influencing male fecundity potential, which also includes (being) overweight, exposure to tobacco smoke, exposure to pollutants," Dr. Remy Slama, who is a fertility expert at France's Joseph Fourier University, told The Telegraph.
And poor sleep doesn't just affect men's fertility -- HuffPost blogger Dr. Michael Breus notes that sleep can also have an impact on women's fertility by affecting levels of ovulation-regulating hormones.
For more surprising things that can affect men's fertility, click through the slideshow: