It has been determined that a man’s sleep can directly affect his fertility. Women with men that don’t get enough may find they have more difficulty conceiving. Circadian Rhythms and Fertility How fertile a person is can be directly affected by the amount of sleep they get each night. Generally, the body is meant to properly function when it gets enough rest. The natural sleep-and-wake cycle, known as the circadian rhythm, allows the human body to function normally and affects the reproductive system as well. It plays a key role in things such as sleeping, eating and hormone production. As a result, if a person is not getting an adequate amount of rest, his or her system is impaired. In the case of a man who has inadequate sleep and disruptions in his circadian rhythm, his sperm production can be adversely affected. Low motility or low sperm count can make it more difficult for a man to impregnate his partner. Not Getting Enough Sleep Leads to Poor Sperm Count According to a study performed at Harbin Medical University in China, men who go to bed late and sleep less can have problems with reproduction. The researchers found that the health of sperm declined and the sperm count itself was lower. Sleeping Nude Improves Sperm Quality A study performed by Stanford University and the National Institute of Child Health and Human Development (NCIHD) came to the conclusion that men who sleep in the nude are more fertile. This finding isn’t surprising since tight underwear can constrict and overheat the testicles and result in poor sperm quality and a lower sperm count. Overall, men who are looking to start a family should aim for at least seven to eight hours of sleep and turn in before midnight. They should also consider wearing loose-fitting underwear like boxers or no underwear at all to increase their fertility and the chances of conceiving with their partner.