Sleep duration linked to sperm structure

Sleep duration is associated with sperm integrity, according to a recent study in China.

Researchers analysed sperm and sleep duration in 796 male volunteers from local colleges between 2013 to 2015.

'This is new information after our previous finding that sleep duration has an inverse U-shaped association with semen volume and total sperm count,' said Dr Jia Cao of Third Military Medical University (TMMU) in Chongqing, China, and co-author of the study. 

Previous research in 2016 had shown a relationship between sleep duration and sperm count and semen volume, which were highest in volunteers that had between 7 – 7.5 hours of sleep per day. Participants who had longer or shorter sleep showed lower count and semen volume.

The latest study from TMMU used the same population of volunteers to observe the relationship between high DNA stainability (HDS) in sperm and sleep duration. HDS is used as an indicator for the maturity of sperm chromatin; a high HDS index indicates immature chromatin in sperm, which has previously been linked to low motility. 

Volunteers answered a questionnaire on sleep duration of volunteers and provided semen samples.

HDS was highest in volunteers that had between 7 – 7.5 hours of sleep per day, meaning they had the highest proportion of chromatin-immature sperm. But volunteers who had over 9 hours of sleep, or 6.5 hours or less, showed a decrease in HDS of nearly 41 percent and 30.3 percent, respectively.

The researchers say their findings highlight the complex relationship between sleep duration and male reproductive health, and further research is needed to explore this relationship.

The study was published in the Journal of Sleep Research.