Sleep Behaviours Effect on Sperm Count Deciphered

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Sleep behaviour affects sperm count independently


In this study, sperm count is independently affected by sleep chronotype, sleep duration & social jetlag. The cumulative effect of sleep duration and social jetlag on total sperm count in the 3 chronotypes was -25.7% (earlier), -25.6% (intermediate) and -30.7% (later).


Previous studies reported that both a lack or excess of sleep duration has a negative impact on semen parameters, including sperm count.

In 2017 a clinical trial involving healthy men revealed that a later sleep midpoint time also decreased sperm count.

Similarly social jetlag, which best describes the change in sleep pattern from weekdays to weekends, has also been associated with reduced sperm count.

However, the question whether or not all 3 sleep behaviours affect sperm count independently of each other is currently unknown.

At the same time an individuals sleep chronotype (lark or owl) has also been linked to sleep duration and social jetlag, which may further alter the optimal sleep pattern.


To investigate the relationship between chronotype and sperm count taking into account sleep duration, sleep midpoint time, and social jetlag.


A total of 796 Chinese males enrolled in the MARHCS (Male Reproductive Health in Chongqing College Students) study were assessed against a strict inclusion / exclusion criteria.

Males diagnosed with urogenital system inflammation, epididymitis, testicular injury, incomplete orchiocatabasis, a history of varicocele medication, absence of prominentia-laryngea/pubes/testis, abnormal breast/penis, epididymal knob or varicocele were automatically excluded from the study to minimise any bias.

Sleep chronotype and behaviours was then estimated using the validated Munich Chronotype Questionnaire (MCTQ) and semen samples collected following 2 to 7 days of abstinence.

Semen sample analysis was carried out within 1 hour of sampling, using computer-aided sperm analysis, of at least six areas and 400 sperm, to minimise human error.In this study, sleep duration was defined as the period from sleep onset to sleep end, with the midpoint specifically being the middle time point, whilst social jetlag was the absolute difference between the workday and free-day midpoints.

A variety of statistical methods (Pearson correlation, nonlinear regression, path analysis) was utilised to evaluate the potential relationship between chronotype, sleep behaviours and sperm count.


As per MCTQ recommendations, only data from 667/796 males was accepted for final analysis. For transparency, no difference in baseline characteristics or sperm count was observed between the 667 included males and 129 excluded males.

This final cohort of males, had a mean sleep duration, midpoint time and social jetlag of 7.8 ±0.8 hr, 04:36 ±0.7 hr and 1.0 ±0.6 hr, respectively.

Initial (univariate) analysis showed that sleep duration, midpoint and social jetlag, all correlated with sperm count independent of each other. This correlation remained true after adjustment for age, abstinence period, BMI, smoking, alcohol, tea, coffee and cola.

After advanced statistical analysis, each hour of sleep duration restriction or excess from the mean was associated with an overall -17.6% change in sperm count, whist each hour of social jetlag was linked to -14.5% change in sperm count.

Analysis of chronotypes according to the 3 types: earlier, intermediate and later, showed a sleep duration excess of 0.93 hr, 0.73 hr, and 0.66 hr respectively, leading to a decrease in sperm count of 16.3%, 12.8% and 11.6% respectively.

Similarly social jetlag across the 3 chronotypes was 0.64 hr (earlier), 0.88 hr (intermediate) and 1.32 hr (later), causing an independent decrease in sperm count of 9.3%, 12.8% and 19.2% respectively.

Overall the estimated cumulative effect of sleep behaviour in the three chronotypes was -25.7%, -25.6% and -30.7%.

The authors noted that men of earlier chronotype had a higher preference for improper sleep duration, while men of later chronotype had a higher preference for social jetlag, which potentially masked the individual correlations in previous studies.


  1. Observational study.
  2. Narrow demographic (young college students only).


This study was supported by grants from the National Natural Science Foundation of China and the National Key R&D Program of China.


Inflammation of the epididymis, a highly convoluted duct behind the testis, along which sperm passes to the vas deferens.

A person who habitually gets up early and feels energetic early in the day.

Descent of testis.

A person who habitually goes to bed late and feels energetic in the evening.

Adam’s apple.

Similar studies

Liu K, et al. (2020). Adverse effects of circadian desynchrony on the male reproductive system: an epidemiological and experimental study.

Rizk N I, et al. (2020). Attenuation of sleep deprivation dependent deterioration in male fertility parameters by vitamin C.

Cho J W and Duffy J F, (2019). Sleep, Sleep Disorders, and Sexual Dysfunction.

Liu M M, et al. (2017). Sleep Deprivation and Late Bedtime Impair Sperm Health Through Increasing Antisperm Antibody Production: A Prospective Study of 981 Healthy Men.

Chen Q, et al. (2016). Inverse U-shaped Association between Sleep Duration and Semen Quality: Longitudinal Observational Study (MARHCS) in Chongqing, China.

Alvarenga T A, et al. (2015). Impairment of male reproductive function after sleep deprivation.


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