“Can sleep or the lack of it affect my husband’s
fertility?” That was the question a newly wedded wife asked her counselor. And
I guess it is the same question bothering many couples. And answer to the
question is a big YES!
Not sleeping well, too little or too much can indeed
affect a man's ability to impregnate his wife. This is the findings of latest research.
The "sweet spot" appears to be 7 to 8
hours of sleep a night, said study author Lauren Wise, a professor of
epidemiology at Boston University School of Public Health.
Among the 790 couples the researchers followed,
"we found both short and long sleep duration - less than 6 hours or 9 or
more per night - were associated with a reduced probability of pregnancy,"
Wise declared.
Using 8 hours of sleep as the reference point,
men who slept less than 6 or more than 9 hours a night "had a 42 percent
reduced probability of conception in any given month," she added.
The main explanation is most likely hormonal,
Wise said. Fertility experts know that testosterone is crucial for reproduction
and the majority of daily testosterone release in men occurs during sleep, she
explained.
Total sleep time, in turn, has been positively
linked with testosterone levels in several studies, she added.
All of the couples in the study were trying to
conceive, and they had been trying for no more than six menstrual cycles. The couples
answered questions about sleep patterns and whether they had trouble sleeping.
Those men who had trouble sleeping more than half the time were also less
likely to impregnate their partner than those who didn't, the researchers
found.
While the study found only an association between
sleep and fertility, "it can't prove cause and effect," Wise said.
But the link held up even after she took into
account both the men's and women's ages, their body mass index, their frequency
of intercourse, and other factors known to affect fertility. More research is needed, Wise noted.
"It is possible that poor sleep duration
could contribute to an unhealthy lifestyle, decreased libido, a decrease in
sex, but we tried to control for all those factors," she said.
The finding is welcome news to Dr. Peter
Schlegel, vice president of the American Society for Reproductive Medicine.
"There is very little data about how men's
sleep may affect fertility," he said. "We know any stress can affect
fertility for both women and men. This study strongly suggests that for men,
aiming for the 7 to [less than] 9 hours of sleep helps to optimize their
fertility and their chances of contributing to a pregnancy."
Based on this new research, doctors counseling
couples should talk about how much sleep the men are getting, Schlegel said. As
for women and sleep, "we don't know for sure," he said.
Other research suggests that eating more fruits
and vegetables yields better production of sperm than meats and fats, said
Schlegel, who is chair of urology at Weill Cornell Medicine in New York City. Men who are at a healthy
weight generally have better fertility, too.
One limitation of the study, Schlegel said, is
that the researchers did not measure sperm counts. "But they looked at
time to pregnancy," he said, and "most would say the chance of a
pregnancy occurring is probably the best measure."
The findings were to be presented Wednesday at
the American Society for Reproductive Medicine's annual meeting, in Salt Lake City. Research
presented at medical meetings is considered preliminary until it is published
in a peer-reviewed medical journal.
