Of all the things you could be doing in the bedroom during conception, the activity that could matter most isn't what you're thinking. Your fertility depends on your overall health, and sleep is essential for good health. So does sleep affect fertility? Let's explore the connection between sleep and male fertility to find out what you should keep in mind.
“Circadian rhythm” is a term for the natural 24-hour cycle of your body's many processes, which responds to signals of light and dark from your environment. It regulates the intricate machinery of everything that drives “homeostasis,” or equilibrium within your body—from heart rate to hormone secretion and metabolism to motivation for activity. Plus, of course, the need to sleep and the nudge to wake up.
Your sleep-wake cycle is an integral part of your body's balance. Mess with that cycle? You mess with everything, including your fertility.
A literature review released in June 2020 underpins this idea. Researchers explored findings surrounding fertility and circadian rhythms in both human and animal models, finding that:
Let's look at a few key studies that could further unlock our understanding of the connection between sleep and fertility.
A randomized controlled trial in 2017 looked at 981 healthy men to determine what connection sleep deprivation had, if any, on the health and quality of sperm. The groups were divided based on two factors:
The study looked at semen parameters—the count, motility (movement), and morphology (shape) of sperm—as well as the presence of antisperm antibodies (ASA). Antisperm antibodies are immune system cells that mistakenly identify sperm as harmful invaders and attempt to eliminate them, contributing to infertility.
Interestingly, researchers found that short or long sleep durations, as well as late bedtimes, correlated with poor sperm health in terms of motility, survival rate, and even count. A significant increase in ASA production was found in short sleepers, as well.
A 2020 study of 970 patients saw similar results. In this research, patients delivered a semen sample along with a lifestyle questionnaire. Researchers examined sleep quality in relation to sperm count and sperm quality. They found that there was a marked difference in certain semen parameters for the group with poor quality sleep, including:
The bottom line: While sleep deprivation can wreck your overall sperm quality, sleeping for too long may also decrease sperm health. Sleep quality is the most important factor—getting 7–8 hours of quality, uninterrupted sleep is key.
A 2016 study of 50 college students explored the relationship between sleep and the presence of inflammation. They looked at the duration of sleep, sleep quality, sleep latency (the length of time it takes to go from awake to sleeping), and bedtime.
Researchers found that each of the sleep measures below had a strong correlation with the presence of inflammation:
How does this connect to fertility? We know that inflammation can affect sperm production. A 2015 study reviewed evidence connecting the presence of higher-than-normal cytokines—immune substances that promote inflammation—to impaired sperm function. The review also highlighted that many infertile men experience acute or chronic inflammation of the genitourinary tract.
But wouldn't you know if you had inflammation? Not necessarily. The study found that many of these men had no outward symptoms. And this insidious inflammation affected both fertility and the outcome of assisted reproductive technologies.
The bottom line: Inflammation seems to affect your sperm production. A number of factors could cause it, but one you can control is when you go to bed and the length and quality of your sleep.
Hormones and fertility go hand in hand, as the process of producing sperm is driven by the delicate balance of several reproductive hormones:
Sleep deprivation can upset that balance. A 2011 study of 10 college-age men examined the relationship between sleep deprivation and testosterone levels, and found that, on days following 5-hour sleep sessions, testosterone levels were noticeably lower—by 10–15% than after night when subjects were able to be fully rested. Daytime testosterone levels were decreased by 10% to 15% for the subjects who underwent a week of sleep deprivation.
This pattern holds for older men, too. A 2007 study found that, for men ages 64–74, the amount of sleep they got the night before had a significant correlation with their morning testosterone levels. This is especially important for older men, who have lower average testosterone levels in general.
The bottom line: Sleep deprivation likely affects your hormone levels, and low testosterone is associated with more than just infertility—it affects sexual health, obesity and muscle mass, heart health, and even morbidity.
Okay, you're convinced. If you’re trying to find ways to improve your sleep, you may have heard of melatonin, a sleep aid designed to knock you out, but “naturally.”
Not so fast. It’s important to remember that melatonin is a hormone, not an herb—and it may have more widespread impacts on your body.
A study conducted back in 2002 found a correlation between long-term melatonin use and a decrease in semen quality. Researchers examined the effects of a 3mg supplement of melatonin on semen quality over a six-month period. They found that long-term melatonin use decreased sperm concentration and motility in 25% of subjects. For one man, this effect did not reverse, even after the treatment period was over.
The results? There is no quick fix for quality sleep. This is something you’ll have to work on as part of a holistic lifestyle change.
Based on what we know about circadian rhythm and the human body, good quality sleep and male fertility go hand in hand. Legacy recommends between six and nine hours of sleep a night, especially if you’re currently undergoing fertility treatments.
Some suggestions to improve your sleep quality:
Sleep is one factor of many in the picture of your overall reproductive health. If you have infertility or just want to gain a greater understanding of your sperm health, an at-home sperm test could help.