Sleeping too little or too much can affect a man’s ability to impregnate his partner, a new research suggests.
According to a health news platform, HealthDay, the “sweet spot” appears to be seven to eight 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 six hours or nine or more per night — were associated with a reduced probability of pregnancy,” Wise said.
Using eight hours of sleep as the reference point, men who slept less than six or more than nine hours a night “had a 42 per cent 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.
A consultant obstetrician and gynaecologist at the University College Hospital (UCH), Ibadan, Dr Gbolahan Obajimi, while reacting to the findings, held that stress might be caused by lack of sleep or any other factor and it could impact both male and female fertility.
He said, however, “One cannot categorically say that too little sleep can affect fertility as the study suggests. Until it has a wide application, I might not be able to comment. I need to study it,” Dr Obajimi said.
According to him, “lack of sleep can lead to stress and stress can lower the fertility hormones. There is not a new thing in what the study is bringing out. It is not particularly a new except if the study is looking at the angle of sleeplessness. However, one cannot categorically say that too little sleep causes infertility as the study suggests, unless it has wide application.”
On the efficacy of increased intake of fruits and vegetables to aid fertility, Dr Obajimi said: “Fruits have antioxidants, they can help the body to remove wastes and toxins and that may be helpful. For fertility, we give Vitamin A, E and other supplements that are present in fruits. So, fruits keep the body in shape and as such, are helpful for fertility. But this does not mean that if you take a particular fruit, you will get pregnant or become more fertile. Fruits keep the body healthy, and a healthy body will be able to reproduce.
Can disrupted bedtime, stress or emotional issues affect fertility? The medical practitioner said some women, when stressed, will not see their period, without which pregnancy is impossible. For men, he said, stress could affect erection.
“They do not have good erection again, because these things can affect libido. They can affect man psychologically and emotionally. And emotional disturbance usually manifests in loss of libido or lack of interest in sex for men. Even when they want to have sexual intercourse, they cannot achieve an erection because their minds are preoccupied. It does not affect the ability to father a child but the process of sexual intercourse is disturbed,” he said.
He also said loss of sleep increases stress and this can affect libido. “Loss of sleep increases stress.