New study suggests too little (or too much) sleep can harm a man’s fertility

New study suggests too little or too much sleep can harm a man’s fertility. Researchers hypothesize this has something to do with testosterone levels.

Do you feel like you get enough sleep?  Me neither.  Even as a teenager, when I slept so much that I was often compared to a sloth (miss those days!), I still never felt like I got enough.

We know that sleep is important for your overall health and energy, but a new report from the Boston University School of Public Health Pregnancy Study Online (PRESTO) suggests that sleeping too much or too little might also be important for men’s fertility.  The PRESTO study gathers data from couples trying to conceive naturally to identify relationships between health and lifestyle factors with successful pregnancies.  In this case they looked at 790 couples trying to conceive within a 12-month period and asked how much sleep they have gotten and if they had trouble sleeping. The researchers also controlled the couples’ ages (men had to be 21 or older while females were between the ages of 21 to 45), intercourse frequency, alcohol intake, and other factors that may affect fertility. The results? Men who slept less than 6 hours or more than 9 hours on average had a 42 percent lower probability of getting their partners pregnant any given month than men who sleep 7 to 8 hours each night. Yes, 8 really is now the magical number. Perhaps a good rule of thumb is to break your day into thirds: 8 hours for working, 8 hours for sleeping, and 8 hours for whatever else you like to do (including baby-making).

Lauren Wise, Professor of Epidemiology at Boston University School of Public Health and the lead researcher for the PRESTO study, said the study may have found a link between sleep and fertility but it does not prove a cause and effect. There needs to be more research, especially on the measurement of sperm count (something the study did not analyze) and maybe even on a women’s sleeping patterns and their fertility.

“The cause is most likely hormonal”, Wise said. Testosterone is especially crucial for sperm production and the majority of daily testosterone release in men occurs during sleep. Total sleep time, in turn, has been “positively linked with testosterone levels in several studies,” she added.

Before this study there was little data on fertility and sleep. Now couples who are trying to get pregnant should think about their sleep cycles (and in particular how to improve it) as a way to boost their chances.


Lauren Wise, Sc.D., professor, epidemiology, Boston University School of Public Health; Peter Schlegel, vice president, American Society for Reproductive Medicine, and professor and chair,  urology, Weill Cornell Medicine, New York City; Oct. 18, 2016, presentation, American Society for Reproductive Medicine annual meeting, Salt Lake City Place