Outdoor artificial light at night and male sperm quality: A retrospective cohort study in China

Nov 17, 2023Environmental pollution (Barking, Essex : 1987)

Outdoor artificial light at night and its link to male sperm quality in China

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Abstract

A 100-unit increase in chronic outdoor artificial light at night is associated with a decline in sperm motility rates among sperm donor candidates.

Chronic exposure to outdoor artificial light at night may negatively impact various sperm quality parameters.
Every 100-unit increase in chronic outdoor artificial light is linked to a decrease of -0.043 in Linearity and -5.523 in Curvilinear velocity.
The non-progressive motility rate is associated with a change of -3.873 for every 100-unit increase in outdoor artificial light.
Sperm motility rate declines by -4.740 per 100-unit increase in chronic exposure to outdoor artificial light.
Similar associations with sperm quality were observed for acute exposure to outdoor artificial light.
The most pronounced effects on sperm quality were noted in males under the age of 25 years.

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Due to the worldwide increased rate of infertility among reproductive-age couples, there is a growing interest in the relationship between environmental stimuli and human sperm quality. While animal studies have demonstrated the detrimental effects of outdoor artificial light at night (ALAN) on sperm quality, investigations based on human data are lacking. Therefore, we conducted a retrospective cohort study involving 1991 sperm donor candidates and employed multivariate linear regression and restricted cubic spline models to quantify the association between outdoor ALAN and sperm quality. The aim was to determine whether there exists an association between exposure to outdoor ALAN and sperm quality. The study included 1991 sperm donor candidates with the following characteristics: mean [SD] age, 24.98 [4.78] years; mean [SD] BMI, 22.13 [2.60] kg/m; mean [SD] sleep duration, 7.66 [1.07] hours/day. Outdoor ALAN exposure of study participants ranged from 0 to 100 nW/cm/sr. Multiple regression analysis on chronic exposure (0-90 days before sperm donation) and human sperm quality revealed the following associations: for CASA primary motion parameters, every 100-unit (nW/cm/sr) increase in chronic outdoor ALAN was associated with a change of -0.043 [95%CI: 0.073, -0.014] in Linearity (LIN), and -5.523 [95%CI: 9.100, -1.946] in Curvilinear velocity (VCL). For CASA secondary motion parameters, every 100-unit (nW/cm/sr) increase in chronic outdoor ALAN was associated with a change of -3.873 [95%CI: 4.926, -2.748] in non-progressive motility rate (NP). Furthermore, the primary sperm quality parameter exhibited a decline of -4.740 [95%CI: 8.853, -0.628] in sperm motility rate per 100-unit (nW/cm/sr) increase in chronic outdoor ALAN. Similar associations were also observed for acute exposure (0-9 days before sperm donation). This retrospective study suggests that poorer sperm quality is more prevalent among adult males residing in areas with higher levels of outdoor ALAN, with a particularly pronounced impact observed in males below the age of 25 years. 2 2 2 2 2

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Outdoor artificial light at night and male sperm quality: A retrospective cohort study in China

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