A Chinese study has found a link between sleep duration and a measure of chromosomal health in sperm.
In the study of 2,020 semen samples provided by 796 male volunteers from colleges in Chongqing (China) from 2013 to 2015, volunteers with more than 9 hours per day of sleep and those with 6.5 hours or less per day sleep had 41% and 30% lower High DNA Stainability – an index that represents the proportion of sperm with abnormal chromatin – than did volunteers with 7 to 7.5 hours per day of sleep. Chromatin is a complex of DNA and proteins that forms chromosomes.
“This is new information after our previous finding that sleep duration has an inverse U-shaped association with semen volume and total sperm count. In the previous study, we found that these two semen parameters were highest when sleep is 7.0 to 7.5 hours per day, and either longer or shorter sleep was associated with the decrease of the two semen parameters.,” said Dr Jia Cao, co-author of the study at the Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing, China.
This study explores whether sleep duration is associated with sperm chromatin integrity. To do so, we conducted a three-phase panel study of 796 male volunteers from colleges in Chongqing (China) from 2013 to 2015. Sleep duration was measured using a modified Munich Chronotype Questionnaire. Sperm DNA integrity was examined via Sperm Chromatin Structure Assay and Comet assay. Setting 7–7.5 h day−1 of sleep duration as a reference, either longer or shorter sleep duration was associated negatively with high DNA stainability (HDS) (P = 0.009), which reflected the immaturity of sperm chromatin. The volunteers with > 9.0 h day−1 sleep and those with ≤ 6.5 h day−1 sleep had 40.7 and 30.3% lower HDS than did volunteers with 7–7.5 h day−1 sleep. No association was found between sleep duration and DNA fragmentation index or Comet assay parameters. This study suggests that sleep duration is associated with sperm chromatin integrity. Further studies are required to validate these findings and investigate the mechanism underlying this association.
Xiaogang Wang, Qing Chen, Peng Zou, Taixiu Liu, Min Mo, Huan Yang, Niya Zhou, Lei Sun, Hongqiang Chen, Xi Ling, Kaige Peng, Lin Ao, Huifang Yang, Jia Cao, Zhihong Cui