A good night’s sleep been shown to be essential to overall health and well-being, with studies showing that seven to eight hours a night is optimal for adults.
But good sleep is something that fewer and fewer of us are getting. The pace of modern living and the amount of time people spend in front of computer screens are to blame, say the experts, who point to a worldwide “sleep epidemic.”
Almost a third of Canadians report not getting enough sleep, and Canada ranks as the third most sleep-deprived country according to a 2016 study across 13 countries.
Sleep deprivation can lead to range of health issues including high blood pressure, heart disease and stroke, and a lack of good sleep can interfere with proper immune functioning and, significantly, reproduction. A 2013 study involving 953 Danish men found that those with sleep disturbances were more at risk for lower sperm concentration, lower sperm count and poorer sperm motility, a measure of how well sperm are able to move about.
Now, researchers with the Department of Obstetrics and Gynecology at Harbin Medical University in Harbin, China, have found that not only are shorter- and longer-than normal sleep patterns linked to impaired sperm health but that going to bed late (after midnight, particularly) can negatively impact sperm health.
Researchers recruited 981 healthy male adults between the ages of 18 and 50, all of whom had good and regular sleep durations and ideal bedtimes over the previous six months, and divided them into three groups: one which were given a sleep regimen of light’s out between 8 and 10 pm, one between 10 pm and midnight and the third after midnight. Then, each group was further divided into three subgroups depending on assigned sleep length: less than six hours, between seven and eight hours or longer than nine hours.
The researchers conducted regular semen analyses to determine sperm count, shape and motility, with the results showing that participants having shorter sleep durations had lower sperm counts, lower motility and lower sperm survival rates in comparison with the average- and long-sleep groups. But the study also concluded that those with later bedtimes had lower sperm counts and worse survival rates, showing that time of sleep as well as duration can play a role in sperm health.
“Based on the effect of late bedtime on reduction of sperm production, it is likely that a later bedtime could reduce the depth of sleep, which in turn can lead to poor sleep quality on subsequent nights due to feeling sleepy the next day,” say the researchers.
Researchers tested for the presence of antisperm antibodies (ASA), immune system cells found in bodily fluids like blood and semen that attack healthy sperm, in each participant and found that the short-sleepers but not the late-to-bed sleepers had higher levels of ASA, indicating that bedtime may play a role in sleep health independent from the effects of sleep duration.
“Since the lower ASA level in the short sleepers was not associated with changes in the research-set bedtimes, it is likely that the effect of bedtime in impairing sperm health was a separate factor, with a potential effect on production of sperm cells,” say the study’s authors. “Further research is needed to determine the exact mechanism involved.”
The study was published in the journal Medical Science Monitor.