Association of Sleep Disturbances With Reduced Semen Quality

A Cross-sectional Study Among 953 Healthy Young Danish Men

Tina Kold Jensen; Anna-Maria Andersson; Niels Erik Skakkebæk; Ulla Nordstrøm Joensen; Martin Blomberg Jensen; Tina Harmer Lassen; Loa Nordkap; Inge Alhmann Olesen; Åse Marie Hansen; Naja Hulvej Rod; Niels Jørgensen


Am J Epidemiol. 2013;177(10):1027-1037. 

In This Article

Abstract and Introduction


Several studies have found an association between sleep duration and morbidity and mortality, but no previous studies have examined the association between sleep disturbances and semen quality. We conducted a cross-sectional study among 953 young Danish men from the general population who were recruited in Copenhagen at the time of determination of fitness for military service between January 2008 and June 2011. All of the men delivered a semen sample, had a blood sample drawn, underwent a physical examination, and answered a questionnaire including information about sleep disturbances. Sleep disturbances were assessed on the basis of a modified 4-item version of the Karolinska Sleep Questionnaire, which includes questions on sleep patterns during the past 4 weeks. Sleep disturbances showed an inverse U-shaped association with sperm concentration, total sperm count, percent motile and percent morphologically normal spermatozoa, and testis size. Men with a high level of sleep disturbance (score >50) had a 29% (95% confidence interval: 2, 48) lower adjusted sperm concentration and 1.6 (95% confidence interval: 0.3, 3.0) percentage points' fewer morphologically normal spermatozoa than men with a sleep score of 11–20. This appears to be the first study to find associations between sleep disturbances and semen quality. In future studies, investigators should attempt to elucidate mechanistic explanations and prospectively assess whether semen quality improves after interventions restoring a normal sleeping pattern.


Several studies have found a U-shaped relationship between sleep duration and morbidity, mortality, and obesity, with the lowest risk being observed among persons who sleep 7–8 hours per night.[1–3] The mechanism may be mediated through changes in hormone regulation, metabolism, or an unhealthier lifestyle. Sleep disturbances also seem to affect mortality,[4] but the health effects of sleep quality have been studied less extensively. The frequency of sleep disturbances has increased in the industrialized world during the past few decades, a period in which a decline in semen quality has also been reported.[5] To our knowledge, no previous studies have directly examined the association between sleep disturbances and semen quality, but Leproult and Van Cauter[6] recently reported that 1 week of sleep restriction to 5 hours per night resulted in a 10%–15% decrease in serum testosterone levels. The suggested association with lower serum testosterone levels among the sleep-disturbed has been reported among older men, although some studies were unable to corroborate this finding.[7–9]

We studied the association between self-reported quality of sleep during the past 4 weeks and semen quality and male reproductive hormone levels in a population of 953 young, healthy Danish men.