Aside the limited studies exploring the link between psychosocial working conditions and sperm quality or male fertility challenges, existing evidence on these associations is inconclusive. For instance, evidence linking shift work and job stress to male fertility challenges and sperm quality is inconsistent. And the association between sperm quality and long working or sitting hours has been inconclusive. However, personal factors or socio-demographic factors like education, lifestyle risk factors such as smoking, depression, diabetes, and poor-quality sleep, are linked to poor sperm quality.

Shift work, male infertility, and sperm quality

Non-standard shift workers may be at heightened risk for poor quality sleep, such as daytime sleepiness and insomnia, due to circadian rhythm disruption [23]. The disruption of the brain-gonadal axis caused by rotating shift work schedules was related to circadian rhythm interference, which can ultimately cause infertility and poor sperm quality [34]. It is worth noting that shift workers experience acute sleep loss of 13 h for 14 days of day shift [35]. Besides, evidence showed that hypogonadal men may be experiencing decreased libido and erectile dysfunction [20]. Moreover, workers with non-standard shifts have low blood testosterone levels and erectile dysfunction, which are likely to be a result of poor-quality sleep [36]. Then, shift workers with good-quality sleep and recovery periods may not have challenges with blood testosterone levels, erectile functioning, and sperm quality. Evidence shows that permanent workers without sleep problems usually have no issues with infertility and sperm quality [17]. Hence, the association between shift work and infertility in men and sperm quality may be explained by quality sleep levels, where sleep deficiency may lead to fatigue which subsequently compromises male potency. However, our assertion is that more evidence is needed in this area.

Job stress and sperm quality

The association between job strain or occupational stress and sperm quality is explained by the neuroendocrine system among distressed male workers who may be without adequate resources for coping with such stress [37]. The hypothalamic-pituitary-adrenal (HPA) axis is activated under conditions of excessive exposure to psychosocial work stress, leading to an increase in glucocorticoids in the body, which further stresses the secretion of male sex hormones. The most widely recognised argument is that a high level of glucocorticoids would first block the manufacture and excretion of testosterone by Leydig cells and subsequently interfere with spermatogenesis [38]. Second, an active HPA axis would decrease gonadotropin hormone-releasing or hormone secretion via the glucocorticoid receptor (GCR), which may lead to hypogonadotropic hypogonadism and suppression of the hypothalamic-pituitary-gonad (HPG) axis [39], thus, compromising sperm quality.

Other relations may potentially explain the negative impact of psychosocial work stress on sperm quality. For instance, Leydig cells may undergo apoptosis or age-related degeneration because of the high levels of glucocorticoids, which would decrease semen quantity in the testis [40]. Another link is the gross chromosomal rearrangements mediated apoptosis of pachytene spermatocytes and spermatogonia [41]. Moreover, it has been suggested that DNA damage and oxidative stress may play a role in testicular function damage brought on by intense psychosocial work stress [42]. Thus, workplace psychosocial stress has the propensity to physiologically and genetically disrupt sperm quality and possibly alter male fertility. Hence, further understanding of these interactions is essential to providing evidence-based psychosocial interventions to safeguard sexual health of male workers.

Job resources and sperm quality

The non-significant association between occupational stress or job strain and semen parameters may be due to the availability of high job resources to male workers who experience such worksite psychosocial stress [15]. Cortisol level may play a role in how social support can lessen the negative effects of work stress on sperm quality. Studies have shown that social support reduce cortisol release and the subjective effects of stress on sperm quality [43]. Moreover, social support may reduce physiologic reactivity to psychological discomfort, potentially protecting workers exposed to psychosocial work stress from the negative effects of stress-induced cortisol surge [44]. Essential job resources such as supportive supervisors and co-workers, increased job control, and provision of adequate recovery periods that in turn promotes sleep may reduce the level of glucocorticoids in the body. This is likely to lower the deteriorating effects of cortisol on sperm quality and protect male fertility. Therefore, such workplace social supports provide buffering effects for male fertility through reduction of negative influence of cortisol on sperm cells. However, this mechanism will benefit from further research, including longitudinal cohort studies.

Smoking and sperm quality

Reviewed studies showed that workers who smoke are more vulnerable to poor sperm quality. Perhaps, several of the harmful and mutagenic chemicals in tobacco or cigarettes can get through the blood testis barrier and alter sperm parameters [45]. In addition to being linked to the pathogenesis of male infertility, tobacco smoke is a mutagen and an aneugen of spermatozoa. Tobacco smoking has been associated with genetic abnormalities in the smoker’s spermatogonia stem cells and their progeny [45]. Moreover, smoking can change the expression of certain microRNAs in sperm, which results in altered DNA methylation patterns in other cell types, some of which persist even after smoking is stopped [45]. Smoking and using illicit drugs may be strategies workers use to cope with demanding work, hostile work environments, and job strain [45]. Thus, though smoking may be a lifestyle issue, it may be resulting from precarious work exposes among male workers. Unfortunately, this interaction between facing hostile work environment and engaging in smoking by workers can cause damage to sperm cells and makes males prone to infertility. Though smoking can independently compromise sperm quality, it becomes more devastating when the workplace is also extremely toxic for the male worker.

Diabetes and sperm quality

The precariousness of work environments, such as long working and sitting hours, burnout, and fatigue, may expose workers to physical inactivity and thus, a sedentary lifestyle. Diabetes is highly prevalent in workers with sedentary occupations [46]. However, the mechanisms underlying the link between sedentary jobs and diabetes are still unclear. Perhaps, substituting physical activity for sedentary behaviours lowers energy expenditure which may be responsible for the positive relationship between sitting time and diabetes, because decrease metabolism is associated with sedentariness.

Male sexual and reproductive function are negatively impacted by diabetes, which reduces serum testosterone levels and semen volume, impairs spermatogenesis, and causes poor libido, erectile dysfunction, problems ejaculating, and infertility [47]. Proliferating cell nuclear antigen (PCNA) is an intranuclear polypeptide that is crucial for controlling the cell cycle. It encourages spermatogonia to undergo mitosis and spermatocytes to undergo meiosis, hastening the production of sperm cells. In male infertility patients, PCNA may partially affect the spermatogenic function of the testis [48]. However, diabetes impairs the expression of PCNA in the testicular tissues, and as the disease progresses (blood glucose levels rise), PCNA expression significantly declines, impairing testicular function [49].

Long-term physiological hyperglycemia in workers with diabetes may trigger the body’s oxidative stress response and damage vascular endothelial cells, leading to anatomical abnormalities in the testis and epididymis [50]. At the same time, high blood glucose can impair the hypothalamic-pituitary-gonadal axis’ ability to regulate itself, alter the number and morphology of testicular interstitial cells, and result in Sertoli cell degeneration [50]. These changes reduce the ability of the Sertoli cells to synthesise and secrete testosterone, which hinders the formation and maturation of sperm cells and negatively affects reproductive function of males [51]. Hence, interventions targeting the management of diabetes among workers may be essential in improving male fertility and general well-being.

Policy recommendations

Male workers on rotating shifts may need adequate rest or recovery periods to limit the impact of fatigue and poor sleep quality on their sperm quality. Moreover, providing sufficient job resources such as social support, job control, and access to healthcare will help deal with the stressful work environment and consequently improve the reproductive health of male workers. Thus, a favourable work environment with a high level of psychosocial safety climate, including adequate job resources that have the potential to buffer the demanding impact of psychosocial work stress and mental health on fertility and sperm quality in men is needed.

The two main goals of workplace tobacco cessation programmes are to encourage smokers to stop and lessen second-hand smoke exposure to other employees [52]. The number of employees, for example, who use tobacco, will be reduced with the implementation of tobacco-free workplace policies. Although nicotine addiction is usually severe, it may take the tobacco user eight to eleven unsuccessful efforts to quit before they can stop for good [45]. Benefits for health should be designed to support many male workers who attempts to quit tobacco use. Workplace designs targeting the health benefits of quitting smoking should be passive and include sending encouraging text messages, movies that highlight the advantages of quitting smoking, or advice on how to smoke less. Playing games with the smoker or holding live coaching sessions with such workers may also help in smoke cessation [52].

Workplace policies targeting screening for the presence of diabetes and implementation of evidence-based exercise programmes may be essential in a sedentary occupational environment. Enforcing resting periods and ensuring adequate breaks for monotonous and high pace work may reduce sitting time and job strain on workers. Thus, workplace health promotion programmes should target awareness creation by sending reminders about diabetes and encourage healthy lifestyles among workers. Providing diabetic workers space for resting during breaks, testing sugar levels, administering insulin, and taking medication may also help to ensure adherence to treatment therapies to improve sperm quality.

Research recommendations

The association between psychosocial work factors and male fertility and sperm quality parameters needs more research attention, especially among workers from developing economies. Quality studies with robust designs that adjust for confounding variables such as sleep quality, smoking, and history of illness like diabetes and hypertension may help understand the independent effect of psychosocial work factors on sperm quality. Psychosocial work factors such as lone working, work-family conflicts, high psychological and emotional work demands, long working hours, job resources, job insecurity, effort-reward imbalance, hostile or abusive work environment, and job strain may need more research attention to understand the link between these variables and infertility in men and sperm quality. Future studies should replicate the moderating effect of job resources such as social support, job control, and psychosocial safety climate on the effect of high job demand on sperm quality in different occupational groups and job settings. Future studies should rely on objective measures of infertility and sperm quality rather than self-reported measures, which are mostly subjective. Moreover, longitudinal studies are needed, especially in developing countries like Ghana where such studies do not exist. Finally, there is a need for community-based or population-based studies so as to understand the broad spectrum of the phenomenon. The issue is that relying on workers attending fertility clinics tend to overestimate the health condition being studied.

Limitations in the current review

Most of the included studies in this review were cross-sectional surveys, which could be affected by response bias due to self-report measures. Relying on self-report measures may affect the generalisation of study findings and hence, affect the findings of this review. In addition, only studies published in the English language were included in this review. This situation may affect the depth of evidence and volume of papers included in this review. Moreover, there are inherent biases in the included studies, which we believe can affect the findings and conclusions drawn in our review. However, the authors adopted a vigorous search, screening, data extraction and reporting processes that have the capacity to produce reliable and valid evidence from out review.