New research shows that sperm is more active in the middle months of the year, and twice as active in the northern hemisphere summer months of July and August compared to January.

A man's ability to produce sperm may depend on his ability to handle stress, according to a study from Italy that looked at the impact of short- and longer-term stress.

The researchers, who published their findings in the journal Fertility & Sterility, found that men with higher levels of both short- and long-term stress and anxiety ejaculated less semen and had lower sperm concentration and counts.

Men with the highest anxiety levels were also more likely to have sperm that were deformed or less mobile.

“Taken together, our observations strongly suggest that (stress and anxiety) may represent a significant factor involved in male fertility,” wrote the researchers led by Elisa Vellani of the European Hospital in Rome.

Previous research has found that men going through fertility treatment or evaluation have higher stress levels than the average person, and some studies have also shown links between stress and sperm quality, Vellani's team wrote. But nobody had looked at whether short-term increases in stress and long-term anxiety had different effects.

For the study, the team recruited 94 men who were visiting the hospital's fertility clinic for the first time, and, as a comparison group, 85 other men who were not seeking fertility treatments.

Each man provided a semen sample for analysis. The men then answered two surveys that measured their current stress and long-term anxiety on scales ranging from 20 to 80 points, with higher scores indicating greater stress or anxiety.

On average, men in both groups scored between 27 and 40 on the tests, which is not considered “pathological,” the researchers noted.

But when Vellani's group compared the 28 men with the lowest stress and anxiety levels to the 40 men with the highest levels, they found that the stressed men were more likely to have lower sperm concentration and counts.

The most stressed men's sperm were also more likely to be immobile and slightly more prone to DNA breaks.

But Tina Jensen from Rigshospitalet in Copenhagen, who has studied the effects of environmental factors on sperm quality, said it was hard to know how these results might apply to the general population given that some men in the study were already undergoing fertility treatment.

“Do you become stressed from becoming infertile or is stress causing infertility?” she asked.

Vellani's team noted that the association between stress and sperm quality was weaker in men who were not seeking fertility treatment, and who also seemed to have better sperm quality anyway.

They concluded that “social and psychological factors” should be considered when assessing possible causes of infertility and addressed as part of fertility treatment.

Jensen said it's hard to tell how different the most and least stressed men were based on the study report, but agreed that the results are probably most relevant for men who are going through fertility treatment, which itself is very stressful.

“Generally, for normal men it's not important,” she said. - Reuters