Impact of sleep on female and male reproductive functions: a systematic review

The impact of chronic insomnia disorder on menstruation and ovarian reserve in childbearing-age women: A cross-sectional study

OBJECTIVE

Diminished ovarian reserve (DOR) is a disorder characterized by impaired ovarian function. Sleep disorders are disruptions of the circadian rhythm, which appears to be closely linked to reproductive systems. This study aimed to investigate the impact of poor sleep quality on the ovarian reserve of childbearing-age women.

METHODS

A cross-sectional study was conducted in China from June 2021 to March 2023. In total, 102 participants diagnosed with chronic insomnia disorder were included in the study. Questionnaires were administered to assess participants' menstrual patterns, insomnia severity, anxiety, and depression. The anti-Müllerian hormone level and the basal antral follicle count were measured for ovarian reserve evaluation. Correlation analysis and ordinal logistic regression analysis were conducted.

RESULTS

The women with insomnia presented high percentages of hypomenorrhea, premenstrual syndrome, and dysmenorrhea (78.4%, 74.5%, and 46.1%, respectively). Severe sleep disorder in the past month was identified as an independent risk factor for hypomenorrhea and premenstrual syndrome (odds ratio [OR], 2.64 and OR, 2.688; p<0.05). The prevalence of DOR among women with insomnia (33.3%) was significantly higher than the average reported in previous studies for young women. Insomnia duration exceeding 1 year was determined to be an independent risk factor for DOR in women aged 36 to 40 years (OR, 4.5; p=0.033).

CONCLUSION

This study highlights the association between sleep disorders and menstrual problems. Prolonged poor sleep quality in women aged 36 to 40 years was identified as a significant risk factor for DOR. We should pay more attention to improving sleep quality in order to maintain normal ovarian function.

Common mental disorders and risk of spontaneous abortion or recurrent spontaneous abortion: A two-sample Mendelian randomization study

BACKGROUND

The direct causal relationships between common mental disorders (anxiety disorders, broad depression, major depressive disorder (MDD), bipolar disorder, and insomnia) and miscarriage or recurrent spontaneous abortion (RSA) are unclear. Therefore, this study aimed to explore these, using Mendelian randomization.

METHODS

Genome-wide association studies (GWAS) meta-analyses with the largest sample size possible and selected independent single individuals of European ancestry were selected. Inverse variance weighted (IVW) was the main analysis method. The heterogeneity of the instrumental variables (IVs) was assessed using IVW and MR-Egger, and the horizontal pleiotropy of the IVs was assessed using MR-Egger and MR-PRESSO.

RESULTS

Based on IVW results, the four mental disorders were found to be causally associated with spontaneous abortion (anxiety disorder: OR (95%CI), 1.230 (1.063-1.420), P = 0.0050; major depressive disorder: 1.690 (1.239-2.307), P = 0.0009; bipolar disorder: 1.110 (1.052-1.170), P = 0.0001; insomnia: 1.292 (1.076-1.552), P = 0.0060). Furthermore, no causal relationship was observed between broad depression and spontaneous abortion. Five common mental disorders were not causally associated with the RSA.

LIMITATIONS

(1) Our analysis was limited to the European population; (2) the duration of mental disorders was not analyzed, as no information was available; and (3) it was difficult to completely detect genetic pleiotropy.

CONCLUSIONS

Anxiety disorders, MDD, bipolar disorder, and insomnia may contribute to spontaneous abortion. Therefore, we should focus on the mental and sleep health of pregnant women. Future studies may be required on whether mental disorders directly lead to RSA, especially unexplained RSA.

Sleep quality, perceived stress and associated factors in women undergoing IVF treatment: short-term longitudinal study

BACKGROUND

Despite limited studies in the literature, it is hypothesised that lifestyle factors are modifiable habits that have an impact on couples' fertility health. However, the relationship between sleep quality and infertility is an area that needs to be clarified.

OBJECTIVE

To determine sleep quality and associated factors in women receiving in vitro fertilisation treatment and to evaluate the changes in sleep over the treatment cycle.

METHODS

This is a longitudinal descriptive study conducted on 158 women in two infertility centres in Izmir, Turkey. Data were collected using the Personal Introduction Form, Pittsburgh Sleep Quality Index, Visual Analogue Stress Scale, and Physical Symptoms List. Data were collected during three different treatment periods: beginning of the in vitro fertilisation trial, oocyte pick-up day and the postembryo transfer period.

RESULTS

The sleep quality score of women progressively decreased as treatment progressed (p < .001). A strong positive correlation was determined between stress and sleep quality (p < .001). Additionally, advanced age, low education level, shift work, prolonged treatment and economic distress were associated with poorer sleep quality (p < .001). In addition, breast fullness, abdominal distension, and pain (p < .001) observed until the oocyte pick-up day, as well as nausea and fatigue during the postembryo transfer period (p < .001), were identified as physical symptoms affecting sleep quality.

CONCLUSION

This article provides information on sleep quality during in vitro fertilisation and guides healthcare professionals to encourage and improve women's sleep quality.

Association of sleep duration and sleep quality with gestational diabetes mellitus in pregnant women after treatment with assisted reproductive technology: A birth cohort study

Maternal sleep is closely related to subsequent gestational diabetes mellitus (GDM) in natural pregnancies. However, whether this connection exists in pregnant women conceiving with the help of assisted reproductive technology (ART) has not been confirmed. Hence, in this study, we evaluated whether early pregnancy sleep duration or sleep quality is associated with gestational diabetes mellitus in ART-pregnant women, as well as the influence of maternal age on this association. This prospective birth cohort study included 856 pregnant women who successfully conceived with the help of ART treatment. The sleep parameters of ART-pregnant women were assessed using the Pittsburgh Sleep Quality Index (PSQI) in early pregnancy. We explored the association between sleep and the risk of gestational diabetes mellitus using an unconditional binary logistic regression model. Different models were constructed to examine the robustness of the estimation by incorporating different confounding factors. Multivariable logistic regression revealed that sleep duration of more than 10 h among ART-pregnant women was significantly associated with the risk of GDM, and the association between sleep duration and gestational diabetes mellitus varied by maternal age. We found an increased risk of subsequent gestational diabetes mellitus with increasing sleep duration only in pregnant women aged <35 years. Additionally, no statistically significant association between sleep quality and gestational diabetes mellitus was found in this study. In conclusion, excessive sleep duration (≥10 h) is associated with a high risk of gestational diabetes mellitus in pregnant women who conceived with the help of assisted reproductive technology, and maternal age may modify this effect.

Knowledge, attitude and practice on ovarian reserve function among women of childbearing age: a prospective cross-sectional study in Chongqing and surrounding regions

OBJECTIVES

To evaluate the knowledge, attitudes and practice (KAP) on ovarian reserve function among women of childbearing age in Chongqing and surrounding regions, China.

DESIGN

Cross-sectional study.

SETTING

Chongqing and surrounding regions, China.

PARTICIPANTS

Women of childbearing age (18-48 years) by convenience sampling.

PRIMARY AND SECONDARY OUTCOME MEASURES

The demographic characteristics of the respondents and their KAP on ovarian reserve function were collected by administering 38-item questionnaires.

RESULTS

A total of 510 valid questionnaires were collected. The mean knowledge score of all respondents was 7.56±2.03 (possible range: 0-10), the mean attitude score was 29.12±3.98 (possible range: 8-40) and the mean practice score was 23.45±3.58 (possible range: 6-30). The multivariable analysis showed knowledge level (OR 1.175, 95% CI 1.049 to 1.317, p=0.002), attitude level (OR 1.249, 95% CI 1.167 to 1.337, p<0.001) and eating habits (self-cooked vs eating out, OR 1.958, 95% CI 1.201 to 3.190, p=0.007) were independently associated with better practice level. The structural equation modelling analysis showed that knowledge had a direct influence on attitude (β=0.487, p=0.030) and practice (β=0.312, p=0.012) and an indirect influence on practice (β=0.213, p=0.016). Attitude had a direct influence on practice (β=0.438, p=0.007). The total influence of knowledge on practice was significant (β=0.525, p=0.012).

CONCLUSIONS

The women living in Chongqing and surrounding regions had good knowledge, moderate attitude and good practice towards ovarian reserve function. The knowledge aspect can be further improved by education, which in turn might also improve practice among women of childbearing age.

Association of sleep traits with male fertility: a two-sample Mendelian randomization study

Background: Previous observational studies have investigated the association between sleep-related traits and male fertility; however, conclusive evidence of a causal connection is lacking. This study aimed to explore the causal relationship between sleep and male fertility using Mendelian randomisation. Methods: Eight sleep-related traits (chronotype, sleep duration, insomnia, snoring, dozing, daytime nap, oversleeping, and undersleeping) and three descriptors representing male fertility (male infertility, abnormal sperm, and bioavailable testosterone levels) were selected from published Genome-Wide Association Studies. The causal relationship between sleep-related traits and male fertility was evaluated using multiple methods, including inverse variance weighting (IVW), weighted median, Mendelian randomisation-Egger, weighted model, and simple model through two-sample Mendelian randomisation analysis. Mendelian randomisation-Egger regression was used to assess pleiotropy, Cochrane's Q test was employed to detect heterogeneity, and a leave-one-out sensitivity analysis was conducted. Results: Genetically-predicted chronotype (IVW,OR = 1.07; 95%CL = 1.04-1.12; p = 0.0002) was suggestively associated with bioavailable testosterone levels. However, using the IVW method, we found no evidence of a causal association between other sleep traits and male fertility. Conclusion: This study found that chronotype affects testosterone secretion levels. However, further studies are needed to explain this mechanism.

Effect of obstructive sleep apnea on semen quality

BACKGROUND

Obstructive sleep apnea (OSA) has several notable complications such as hypertension and diabetes. Studies have also shown that OSA is associated with erectile dysfunction and reduced androgen levels. However, the effect of OSA on semen quality remains poorly studied.

METHODS

Men attending a tertiary reproductive center for semen analysis were tested with a portable sleep breathing monitor. Patients were divided into four groups based on their apnea hypopnea index: none, mild, moderate, and severe obstructive sleep apnea. Differences between groups were assessed using χ2, and associations were tested with multiple regression analysis.

RESULTS

We included a total of 175 male subjects with a mean age of 32.2 ± 3.6 years. There were significant differences between groups in progressive sperm motility (%) (43 ± 16, 42 ± 17, 36 ± 18, 29 ± 18, respectively; p = 0.002), total motility (%) (59 ± 19, 59 ± 20, 49 ± 21, 42 ± 20, respectively; p = 0.010), and vitality (%) (80 ± 10, 81 ± 11, 79 ± 8, 72 ± 19, respectively; p = 0.039). Asthenospermia (progressive motility < 35%) was significantly more common in subjects with OSA (χ2 = 5.195, p = 0.023). In multiple regression models, after adjusting for age and body mass index, apnea hypopnea index remained negatively and significantly associated with progressive motility, total motility, and vitality.

CONCLUSIONS

OSA is an independent risk factor for sperm motility and vitality, and further investigation is now needed to determine if continuous positive pressure ventilation or other therapies can improve semen quality in these patients.

Evaluation of chronotype and sleep quality in infertile population and comparison with fertile population: a cross-sectional study

PURPOSE

Infertility is a stressful condition for couples and can affect patients' circadian rhythm and sleep quality. The goal of this study is to assess differences in chronotype and sleep quality between infertile and fertile people.

METHODS

A cross-sectional study was conducted. The infertile patient population consisted study group. Primiparous patients without any known gynecological disease who presented for routine cervical cancer screening follow-up were included in the control group. The Turkish version of the Morningness-Eveningness Questionnaire (MEQ) and Pittsburg Sleep Quality Index (PSQI) scores were evaluated between groups.

RESULTS

A total of 227 patients were assessed. There were 110 patients in the study (infertile) group and 117 patients in the control (fertile) group. The evening chronotype proportion (23.6 vs. 0.9%, p < 0.001) was higher in the infertile group. The median of MEQ score was significantly higher in the fertile patients (50, IQR = 43 - 55 vs. 56, IQR = 51 - 59; p < 0.001), and the median of PSQI score was significantly higher in the infertile patients (5, IQR = 4 - 6, vs. 4, IQR = 3 - 5; p < 0.001).

CONCLUSIONS

In this study, we found significantly worse sleep quality, and more evening chronotype in the patients with infertility.

Sleep disorders and risk of infertility: A meta-analysis of observational studies

OBJECTIVE

The purpose of this study was to determine the relationship between sleep disorders and risk of infertility.

METHOD

Three databases (PubMed, Embase, and Cochrane Library) were searched form their inception to April 30, 2023. Information of study design, control group and experimental group, number of participants, and study outcomes was extracted. The quality of the studies was evaluated using the Newcastle-Ottawa Scale (NOS scale) and the Agency for Healthcare Research and Quality (AHRQ scale). Narrative synthesis and meta-analysis were used to analyze these studies.

RESULT

Eight cohort, cross-sectional, and case-control studies were considered. The reviewed studies were high-quality. Pooled analysis showed that the risk of infertility was 1.43-fold higher in patients with sleep disturbance (HR = 1.43, 95% CI, 0.97-2.11, z = 1.79), but this was not statistically different; the risk was 1.58-fold higher in patients with OSA compared to those without OSA (HR = 1.58, 95%, CI, 0.99-2.52, z = 1.91), but this was not statistically significant. Wake-up time is also associated with infertility (OR = 1.14; 95%CI = 1.01-1.28; P = 0.037). For every hour they stay awake beyond 8:00 AM, participants had a 41% higher risk of infertility (P = 0.004). The early-to-bed/late-to-rise (EL), LE, and LL groups had a higher risk of infertility than the EE group.

CONCLUSION

The present study did not find an association between sleep disorders and the risk of infertility. Therefore, more observational studies are warranted to explore the association between sleep disorders and the risk of infertility.

Lactobacillus plantarum secretions may exert a cryoprotective effect on human sperm motility: A prospective in vitro study

BACKGROUND

Semen cryopreservation is a widely used procedure for fertility preservation, despite some level of cryodamage that may occur in spermatozoa after thawing. However, there is some evidence that lactobacilli, one of the bacteria found in semen, might benefit sperm quality.

OBJECTIVES

This study aims to determine whether the addition of Lactobacillus plantarum secretions to sperm freezing medium has an impact on sperm motility, morphology, and DNA fragmentation.

MATERIALS AND METHODS

This is a prospective auto-controlled study. It was conducted on 30 raw semen samples from 30 infertile men attending a fertility center for semen analysis. Before freezing, all the samples were analyzed for motility, morphology, and DNA fragmentation percentages. Each sample was then divided equally into three aliquots. Cryopreservation was performed on each aliquot using one of the following three media: without Lactobacillus plantarum secretions (control group) or with 107 or 108 colony-forming units/mL Lactobacillus plantarum secretions. Sperm motility, morphology, and DNA integrity were evaluated after the cryopreservation media were added and after semen thawing.

RESULTS

The results of this study indicated that after thawing, no statistically significant decrease in progressive motility and non-progressive percentages were detected in the sperm freezing medium supplemented with 108 colony-forming units/mL Lactobacillus plantarum secretions than the fresh raw semen. Moreover, multivariate linear regression model analyses showed that the progressive motility (p = 0.02), non-progressive motility (p = 0.016), and non-motile spermatozoa (p = 0.012) percentages were significantly decreased in the freezing medium (without Lactobacillus plantarum secretions) compared to the fresh raw semen.

DISCUSSION AND CONCLUSION

To the best of our knowledge, this is the first study showing that Lactobacillus plantarum secretions had a cryoprotective effect on sperm motility when added to the sperm freezing medium. Furthermore, Lactobacillus plantarum secretions were found to protect sperm DNA integrity more effectively than the freezing medium without Lactobacillus plantarum secretions in non-normozoospermia group. Cryopreservation procedures must therefore be optimized to minimize any iatrogenically induced sperm DNA damage, given the correlation between sperm DNA damage and increased mutation loads in progeny.

Menstrual disturbances and its association with sleep disturbances: a systematic review

BACKGROUND

Menstrual disturbances harm women's health, and general well-being. As growing evidence highlights the relationship between sleep and menstrual disturbances, it is imperative to comprehensively examine the association between sleep and menstrual disturbance considering the multiple dimensions of sleep. This systematic review aims to identify the association between sleep and menstrual disturbances by evaluating using Buysse's sleep health framework.

METHODS

A comprehensive search of the literature was conducted in PubMed, EMBASE, psychINFO, and CINAHL to identify publications describing any types of menstrual disturbances, and their associations with sleep published between January 1, 1988 to June 2, 2022. Quality assessment was conducted using the Joanna Briggs Institute Critical Appraisal Checklist for Analytical Cross-Sectional Studies. The findings were iteratively evaluated menstrual disturbances and their association with sleep using Buysse's sleep health framework. This framework understands sleep as multidimensional concept and provides a holistic framing of sleep including Satisfaction, Alertness during waking hours, Timing of sleep, Efficiency, and Sleep duration. Menstrual disturbances were grouped into three categories: premenstrual syndrome, dysmenorrhea, and abnormal menstrual cycle/heavy bleeding during periods.

RESULTS

Thirty-five studies were reviewed to examine the association between sleep and menstrual disturbances. Premenstrual syndrome and dysmenorrhea were associated with sleep disturbances in sleep health domains of Satisfaction (e.g., poor sleep quality), Alertness during waking hours (e.g., daytime sleepiness), Efficiency (e.g., difficulty initiating/maintaining sleep), and Duration (e.g., short sleep duration). Abnormal menstrual cycle and heavy bleeding during the period were related to Satisfaction, Efficiency, and Duration. There were no studies which investigated the timing of sleep.

CONCLUSIONS/IMPLICATIONS

Sleep disturbances within most dimensions of the sleep health framework negatively impact on menstrual disturbances. Future research should longitudinally examine the effects of sleep disturbances in all dimensions of sleep health with the additional objective sleep measure on menstrual disturbances. This review gives insight in that it can be recommended to provide interventions for improving sleep disturbances in women with menstrual disturbance.

Declined Live Birth Rate from in vitro Fertilization Fresh Cycles Performed During Chinese New Year Holiday Season

Purpose

This study aims to investigate the impact of the Chinese New Year (CNY) holiday season on the outcomes of In Vitro Fertilization (IVF) fresh embryo transfer cycles.

Participants and Methods

This retrospective study analyzed 4688 patients who received their first IVF fresh cycle attempt between January 2017 and October 2021. Of these, 4449 women underwent IVF during non-holiday seasons, while 239 women were treated during the CNY holiday season. The study included women who underwent IVF treatment during the specified time frame. The primary outcome was the live birth rate (LBR).

Results

The study found that the LBR of IVF performed during the CNY holiday season was 32.22%, which is significantly lower than that of the non-holiday season (43.38%, p<0.001). Multivariate logistic regression analysis showed that the CNY holiday season (OR=0.62, 95% CI 0.47-0.82, p=0.001) was an independent factor associated with the live birth rate. Propensity score matching (PSM) data analysis showed that the LBR in the CNY holiday season group was 31.78% compared to 42.64% in the non-holiday season group (p=0.005). Inverse probability of treatment weighting (IPTW) data also indicated that the CNY holiday season had a lower LBR than the non-holiday season (OR=0.64, 95% CI 0.47-0.87, p=0.005).

Conclusion

IVF performed during the CNY holiday season results in a lower live birth rate, potentially indicating that certain lifestyle adjustments during this period, such as unhealthy dietary, tobacco and alcohol usage, sleep disruption, and emotional stress experienced could have some influence on the outcomes.

Self-reported sleep quality and oligo/astheno/teratozoospermia among men attending an infertility clinic: a longitudinal study

OBJECTIVE

We aimed to examine the influence of sleep disturbances on the risk of oligo/astheno/teratozoospermia (OAT) in men attending an infertility clinic.

METHODS

We consecutively enrolled men attending an infertility clinic from July 2020 to June 2021. Semen parameters were obtained at initial presentation, and the Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale score, and the STOP-BANG Questionnair were completed to assess sleep quality. Embryo outcomes were evaluated after infertility treatment.

RESULTS

Of 466 men enrolled, 119 had OAT (OAT group) and 347 had normozoospermia (NS group). There were no differences between the two groups regarding Epworth Sleepiness Scale and STOP-BANG Questionnaire scores. The prevalence of poor sleep quality (Pittsburgh Sleep Quality Index score ≥ 5) in the OAT group was significantly higher than that in the NS group (42% vs. 29%, p = 0.009). A higher rate of poor subjective sleep quality was observed in the OAT group compared with the NS group (p = 0.005) and Pearson's correlations revealed a negative relationship between subjective sleep quality and semen quality. Logistic regression found that subjective sleep quality was independently associated with an increased risk of OAT (adjusted odds ratio = 0.610, p = 0.007).

CONCLUSIONS

Men with OAT attending an infertility clinic exhibited poor subjective sleep quality. Improving sleep disturbances may be a target intervention to reduce the risk of OAT. This possibility warrants further investigation.

Chronotype and sleep duration interact to influence time to pregnancy: Results from a New York City cohort

STUDY OBJECTIVE

To study associations between nighttime sleep characteristics and time to pregnancy.

METHODS

Pregnant people age ≥18 years and<18 weeks' gestation were recruited from 3 New York University Grossman School of Medicine affiliated hospitals in Manhattan and Brooklyn (n = 1428) and enrolled into the New York University Children's Health and Environment Study. Participants in the first trimester of pregnancy were asked to recall their time to pregnancy and their sleep characteristics in the 3 months before conception.

RESULTS

Participants who reported sleeping<7 hours per night tended to have shorter time to pregnancy than those who slept 7-9 hours per night (adjusted fecundability odds ratio = 1.16, 95% confidence interval: 0.94, 1.41). Participants with a sleep midpoint of 4 AM or later tended to have longer time to pregnancy compared with those with earlier sleep midpoints (before 4 AM) (adjusted fecundability odds ratio = 0.88, 95% confidence interval: 0.74, 1.04). When stratified by sleep midpoint, sleeping<7 hours was significantly associated with shorter time to pregnancy only among those whose sleep midpoint was before 4 AM (adjusted fecundability odds ratio = 1.33, 95% confidence interval: 1.07, 1.67).

CONCLUSIONS

The association of sleep duration with time to pregnancy was modified by chronotype, suggesting that both biological and behavioral aspects of sleep may influence fecundability.

Childbearing, Infertility, and Career Trajectories Among Women in Medicine

Importance

Although women are increasingly represented within medicine, gender disparities persist in time to promotion, achievement of academic rank, and appointment to leadership positions, with no narrowing of this gap over time. Career-specific fertility and family building challenges among women physicians may contribute to ongoing disparities and academic attrition.

Objective

To evaluate delayed childbearing and infertility among women in medicine and investigate the extent to which women physicians may alter career trajectories to accommodate family building and parenthood.

Design, Setting, and Participants

This survey study was conducted among women physicians, with surveys distributed through medical society electronic mailing lists (listserves) and social media from March to August 2022.

Main Outcomes and Measures

Baseline demographic information and fertility knowledge were assessed. Descriptive data on delayed childbearing, infertility, use of assisted reproductive technology, and career alterations to accommodate parenthood were collected. Factors associated with timing of pregnancy and family building regret were assessed using Likert-type scales. Group differences in fertility knowledge, delayed childbearing, infertility, and family building regret were evaluated using χ2 analyses.

Results

A total of 1056 cisgender women (mean [SD] age, 38.3 [7.7] years) were surveyed across level of training (714 attending physicians [67.6%] and 283 residents or fellows [26.8%]), specialty (408 surgical [38.6%] and 638 nonsurgical [60.4%] specialties), and practice setting (323 academic [45.2%], 263 private [24.9%], and 222 community [21.0%] settings). Among respondents, 1036 individuals [98.1%] resided in the US. Overall, 910 respondents (86.2%) were married or partnered and 690 respondents (65.3%) had children. While 824 physicians (78.0%) correctly identified the age of precipitous fertility decline, 798 individuals (75.6%) reported delaying family building and 389 individuals (36.8%) had experienced infertility. Concerning measures taken to accommodate childbearing or parenthood, 199 women (28.8%) said they had taken extended leave, 171 women (24.8%) said they had chosen a different specialty, 325 women (47.1%) said they had reduced their work hours, 171women (24.8%) said they had changed their practice setting, and 326 women (47.2%) said they had passed up opportunities for career advancement among those with children. Additionally, 30 women with children (4.3%) had left medicine entirely.

Conclusions and Relevance

In this survey study, women physicians reported that career-related pressures influenced the timing of childbearing and led to marked alterations to career trajectories to accommodate family building and parenthood. These findings suggest that fertility and family building concerns among women in medicine may contribute to ongoing gender disparities and attrition and represent a potentially critical area for policy reform and future change.

Changes in menstrual cycle length and in sleep-wake behaviors during COVID-19 related lockdown in Israel

COVID-19 related lockdowns changed our life. Studies report that young women are more susceptible to lockdown-induced adverse effects and stress. As stress and menstrual cycle are associated, we hypothesized that menstrual cycle length might change during lockdown. We examined menstrual cycle length, and sleep-wake behaviors during lockdown in Israel. Participants were 97 women in their fertile years who used Tempdrop fertility sensor™ to track cycles. Data were collected before, during and after lockdown in Israel. Our main finding is that lockdown was associated with changes in menstrual cycle length of most participants, with either increased of decreased length. Changes were reversed when lockdown was terminated. Sleep duration increased during lockdown but we found no relationship between sleep and menstrual cycle. We suggest these findings contribute to the understanding of the relationship between stress, sleep, and menstrual cycle. Further studies should explore the sources for differential effects in sub-groups of women.

Alterations in Pregnenolone and Testosterone Levels in Male Shift Workers

Steroid hormone levels are closely related to the endogenous circadian rhythm induced by sleep-wake and dark-light cycles. Shift work that disrupts the circadian rhythm may influence the levels of steroid hormones. The association between shift work and alterations in female sex steroid hormone levels has been studied, but little is known about testosterone and its precursor pregnenolone levels in male shift workers. The present study investigated serum pregnenolone and testosterone levels in a group of shift and daytime male workers. All participants were sampled at the beginning of the morning shift. Lower levels of serum pregnenolone and total testosterone were found in the shift workers compared to the daytime workers. Variations in pregnenolone levels may have consequences for well-being, and they might produce consequences for the levels of hormones downstream of the steroid hormone cascade, such as testosterone. The low levels of testosterone found in shift workers demonstrate the perturbative effect of shift work on testosterone serum levels, which may be independent and/or related to pregnenolone synthesis.

Dietary trends and the decline in male reproductive health

Over the twentieth century, male reproductive health has suffered a substantial decline, as evidenced by decreases in sperm counts and testosterone levels and increases in reproductive pathologies. At the same time, the prevalence of chronic diseases such as obesity, diabetes, and metabolic syndrome has risen dramatically. Metabolic and reproductive health are highly interconnected, suggesting that their respective trends are intertwined and, given the timeframe of such trends, environmental and not genetic factors are most likely to be the primary causes. Industrialization, which began in Europe in the mid-eighteenth century, has resulted in profound changes to our diet, lifestyle, and environment, many of which are causal factors in the rise in chronic diseases. Industrialization results in a nutrition transition from an agricultural unprocessed to a modern processed diet, incorporating increases in sugar, vegetable oils, ultra-processed foods, linoleic acid, trans-fats, and total energy. This dietary shift has incurred numerous adverse effects on metabolic and reproductive health, characterized by chronic inflammation, oxidative stress, and insulin resistance. Moreover, these effects appear to multiply across subsequent generations via epigenetic inheritance. Men's fertility is markedly affected by obesity and diabetes, with an increase in total energy via processed food intake arguably being the key factor driving the diabesity pandemic. In contrast, wholefoods rich in micronutrients and phytonutrients support male fertility and a healthy body weight. Therefore, men wanting to maximize their fertility should consider making positive dietary changes, such as replacing processed foods with unprocessed foods that support metabolic and reproductive health.

Preconception sleep duration, sleep timing, and shift work in association with fecundability and live birth among women with a history of pregnancy loss

OBJECTIVE

To evaluate the associations between preconception sleep characteristics and shift work with fecundability and live birth.

DESIGN

Secondary analysis of the Effects of Aspirin in Gestation and Reproduction study, a preconception cohort.

SETTING

Four US academic medical centers.

PATIENT(S)

Women aged 18-40 with a history of 1-2 pregnancy losses who were attempting to conceive again.

INTERVENTION(S)

Not applicable.

MAIN OUTCOME MEASURES(S)

We evaluated baseline, self-reported sleep duration, sleep midpoint, social jetlag, and shift work among 1,228 women who were observed for ≤6 cycles of pregnancy attempts to ascertain fecundability. We ascertained live birth at the end of follow up via chart abstraction. We estimated fecundability odds ratios (FORs) using discrete, Cox proportional hazards models and risk ratios (RRs) for live birth using log-Poisson models.

RESULT(S)

Sleep duration ≥9 vs. 7 to <8 hours (FOR: 0.81, 95% confidence interval [CI], 0.61; 1.08), later sleep midpoints (3rd tertile vs. 2nd tertile: FOR: 0.85; 95% CI, 0.69, 1.04) and social jetlag (continuous per hour; FOR: 0.93, 95% CI: 0.86, 1.00) were not associated with reduced fecundability. In sensitivity analyses, excluding shift workers, sleep duration ≥9 vs. 7 to <8 hours (FOR: 0.62; 95% CI, 0.42; 0.93) was associated with low fecundability. Night shift work was not associated with fecundability (vs. non-night shift work FOR: 1.17, 95% CI, 0.96; 1.42). Preconception sleep was not associated with live birth.

CONCLUSION(S)

Overall, there does not appear to be a strong association between sleep characteristics, fecundability, and live birth. Although these findings may suggest weak and imprecise associations with some sleep characteristics, our findings should be evaluated in larger cohorts of women with extremes of sleep characteristics.

CLINICAL TRIAL REGISTRATION NUMBER

Clinicaltrials.gov NCT00467363.

The effects of sleep deprivation and obstructive sleep apnea syndrome on male reproductive function: a multi-arm randomised trial

Sleep is essential for the maintenance of health and systemic homeostasis. Decreased sleep time and sleep quality have been associated with a wide range of diseases. To evaluate the effects of obstructive sleep apnea (OSA) and total or selective rapid eye movement (REM) sleep deprivation on male reproductive function, we performed a three-arm parallel study with one pre-defined OSA group and a group of healthy volunteers who were then randomised into total or REM sleep deprivation groups. Questionnaires were completed and overnight polysomnography was undertaken, and blood and sperm samples were collected at the Sleep Institute, São Paulo, Brazil. OSA was diagnosed using questionnaires and polysomnography. Male sexual function was assessed through the questionnaires, blood tests, and semen samples. Data showed an association between OSA and lower circulating levels of total and free testosterone and high-density lipoproteins, as well as a lower proportion of healthy sperm cells and decreased sperm concentration, in comparison to volunteers. Volunteers subjected to either total or REM sleep deprivation had increased circulating levels of thyroid-stimulating hormone, insulin, and higher homeostatic model assessment of insulin resistance (HOMA-IR) values. Both sleep-deprived groups also shown decreased cholesterol, and low-density lipoproteins when compared to their baseline levels, but had no alterations in their spermograms. We observed a reduction in total testosterone following total sleep deprivation, but no effect after REM sleep deprivation. OSA was associated with a hormonal imbalance, which is probably linked with impaired reproductive function and associated comorbidities, such as sleep fragmentation/loss and obesity.

Psychological distress among women undergoing in vitro fertilization-embryo transfer: A cross-sectional and longitudinal network analysis

Background

Women undergoing in vitro fertilization-embryo transfer (IVF-ET) treatment were generally found to experience varying degrees of psychological distress across the treatment. Existing studies focused on total scores and diagnostic thresholds to characterize the symptoms' severity, which might hinder scientific progress in understanding and treating psychological distress.

Aims

We aimed to investigate (a) how depression and anxiety symptoms are interconnected within a network, and (b) the changes of the network (symptom connections and network centralities) over time, in women undergoing in vitro fertilization-embryo transfer.

Methods

A 4-wave longitudinal study was designed with 343 eligible women recruited from the Reproductive Medicine Center of a tertiary hospital in China. The network models were created to explore the relationship and changes between psychopathology symptoms both within and across anxiety and depression, with anxiety measured by the Generalized Anxiety Disorder-7 and depression measured by the Patient Health Questionnaire-9. Symptom network analysis was conducted to evaluate network and network properties, network centrality, and bridge centrality, as well as change trajectory network.

Results

For the strength centrality, "inability to control worry" and "worrying too much" were the most central symptoms at T1; however, these symptoms decreased. The centrality of "sadness" and "guilt" tended to increase steadily and became dominant symptoms. For bridge centrality indices, several bridge symptoms were identified separately from T1 to T4: "irritability," "concentration difficulties," "nervousness," and "restlessness;" "guilt" exhibited increased bridge symptoms. Furthermore, the change trajectory network indicated that "suicide ideation" became more closely related to guilt but not to worrying too much over time.

Conclusion

This study provides novel insights into the changes in central features, connections, and bridge symptoms during IVF-ET treatment and identified several bridge symptoms separately at different stages, which could activate the connection between psychopathology symptoms. The results revealed that sense of guilt was associated with worsening psychopathology symptoms, indicating that future psychological interventions should target guilt-related symptoms as a priority.

The impact of sleep on in vitro fertilization embryo transfer outcomes: a prospective study

OBJECTIVE

To prospectively examine the association between sleep quality before embryo transfer with pregnancy outcomes in a population with infertility.

DESIGN

Prospective observational cohort study.

SETTING

Center for Reproductive Medicine, Shandong University.

PATIENT(S)

From 7,847 women who enrolled from July 2019 to July 2020, 3,183 were eligible.

INTERVENTION(S)

Information about sleep, including sleep quality, sleep duration, and sleep chronology, were collected before embryo transfer using an integrated questionnaire. Sleep quality is quantified by the Pittsburgh Sleep Quality Index (PSQI) with a cut-point of 5 (PSQI >5 identifying poor sleep vs. PSQI ≤5 identifying good sleep). Average weekly sleep duration was calculated and divided into 5 groups (≤7, 7-8, 8-9, 9-10, and >10 h/d). In defining sleep chronotype, women with a sleep midpoint earlier than 2:30 AM were defined as morningness type, whereas those with a sleep midpoint later than 3:30 AM were defined as eveningness type, and the remainder were defined as an intermediate type.

MAIN OUTCOME MEASURE(S)

Rate of clinical pregnancy and live birth.

RESULT(S)

Compared with those reporting poor sleep quality, those reporting good sleep quality showed higher clinical pregnancy (69.3% vs. 65.1%) and live birth rates (50.5% vs. 45.7%). After adjusting for confounding factors, women who self-reported good sleep had a higher probability of acquiring clinical pregnancy (RR, 1.07; 95% confidence interval, 1.01-1.13) and of live birth (RR, 1.12; 95% confidence interval, 1.02-1.23). Women with the morningness chronotype had the lowest rates of clinical pregnancy and live birth and had the highest rate of miscarriage. Sleep duration was found to have no significant association with any outcomes. In the stratified analyses, the positive associations of good sleep quality with clinical pregnancy and live birth existed only among women younger than 35 years old or who had undergone fresh embryo transfer.

CONCLUSION(S)

Good sleep quality was positively associated with outcomes in in vitro fertilization embryo transfer (IVF-ET), particularly with clinical pregnancy and live birth. Poor sleep quality may be a risk factor for adverse IVF-ET outcomes for women <35 years old. Treating sleep disorders and providing sleep behavior guidance to patients receiving IVF-ET may improve pregnancy outcomes.

Maternal Sleep Problems in the Periconceptional Period and the Impact on Health of Mother and Offspring: A Systematic Review

Knowledge of the impact of sleep problems in the periconceptional period is scarce. Since this period is the most sensitive time window for embryonic and placental development, we aim to study the impact of maternal sleep problems in the periconceptional period on both mother and offspring. We systematically searched various databases up until September 2021 for studies reporting on maternal sleep in the periconceptional period and any outcome in mother and offspring. We included observational studies describing maternal sleep problems in the periconceptional period and associations with either maternal and/or offspring outcomes. The search produced 8596 articles, of which we selected 27 studies. Some associations were found between sleep problems and lower fertility, more hypertensive disorders, more mood disorders in mothers, higher risk of preterm birth and low birth weight, and more sleep and behavior problems in offspring, with associations with maternal mood disorders being most consistent. This systematic review shows that maternal sleep problems in the periconceptional period are associated with a higher risk of various adverse outcomes in both mother and offspring, although not consistently. It shows that good sleep during pregnancy is crucial, starting as early as before conception, especially for maternal mood. Therefore, it is important for clinicians to pay attention to sleep problems in the periconceptional period and provide adequate treatment for potential sleep problems, even before pregnancy.

Effects of physical activity and sleep duration on fertility: A systematic review and meta-analysis based on prospective cohort studies

Objective

Subfertility is a common problem for couples in modern society. Many studies have confirmed that lifestyle factors can affect fertility although there are conflicting conclusions relating to the effects of physical activity and sleep duration on fertility. In this study, we aimed to summarize and analyze the available evidence.

Methods

PubMed, Web of Science, Cochrane, and Embase databases (as of October 14, 2022) were systematically searched for eligible prospective cohort studies. Data were extracted and effect values were combined. We also performed methodological quality and bias risk assessments for all the included studies.

Results

A total of 10 eligible articles were included in our analysis; seven investigated the relationship between physical activity and fertility, and three investigated the effect of sleep duration on fertility. Compared with the lowest level of physical activity, high intensity physical activity (the highest levels of physical activity) was negatively correlated with fertility [odds ratio (OR) = 0.84; 95% confidence interval (CI): 0.70, 1.00, I ² = 64%]. However, we did not find an association between moderate intensity physical activity and fertility (OR = 1.09; 95% CI: 0.98, 1.22, I ² = 60%). We observed an inverse association between limited sleep duration (≤ 7 h) and fertility (OR = 0.92; 95% CI: 0.84, 1.00, I ² = 0%) compared with 8 h of sleep. The relationship between long sleep duration (≥9 h) and fertility was not statistically significant (OR = 0.85; 95% CI: 0.60, 1.21, I ² = 83%). According to the Newcastle-Ottawa Scale score, the overall quality of the research articles included was ranked as medium to high (6-9). Through GRADE system, the quality of evidence for the impact of high intensity physical activity and limited sleep duration on fertility was moderate, while the quality of evidence for the impact of moderate intensity physical activity and long sleep duration on fertility was low.

Conclusion

The current evidence shows that high intensity physical activity and limited sleep time are negatively related to fertility. But there was great heterogeneity among studies, and the quality of research evidence was low to median. Thus, further high-quality research is needed to confirm this conclusion.

PROSPERO registration number

CRD42022298137.

Women's quality of sleep and in vitro fertilization success

Women undergoing in vitro fertilization (IVF) are emotionally challenged. Anxiety, depression, and sleep disturbances are common complaints. The impact of these symptoms on IVF outcome is however debated. In this study, we aimed at investigating whether sleep quality and psychological health can affect the chances of success of the procedure. Women undergoing IVF were recruited at the time of oocytes retrieval. Women's sleep quality and psychological health was assessed using the Pittsburgh Sleep Quality Index (PSQI), the Fertility Problem Inventory (FPI), and the Hospital Anxiety and Depression Scale (HADS). Baseline characteristics and results of the three scales were compared between women who did and did not succeed. Overall, 263 women were included, of whom 81 had a clinical pregnancy (31%). As expected, successful women were younger, and their ovarian reserve was more preserved. FPI and HADS scores did not differ. Conversely, a statistically significant difference emerged for the PSQI score, the median [interquartile range] in pregnant and non-pregnant women being 4 [3-5] and 5 [3-7], respectively (p = 0.004). The crude and adjusted OR of pregnancy in women with a PSQI > 5 (indicating impaired sleep quality) was 0.46 (95% CI 0.25-0.86, p = 0.02) and 0.50 (95% CI: 0.26-0.94, p = 0.03), respectively. In conclusion, low sleep quality is common in women scheduled for IVF and could influence the success of the procedure.

Associations between insomnia and pregnancy and perinatal outcomes: Evidence from mendelian randomization and multivariable regression analyses

BACKGROUND

Insomnia is common and associated with adverse pregnancy and perinatal outcomes in observational studies. However, those associations could be vulnerable to residual confounding or reverse causality. Our aim was to estimate the association of insomnia with stillbirth, miscarriage, gestational diabetes (GD), hypertensive disorders of pregnancy (HDP), perinatal depression, preterm birth (PTB), and low/high offspring birthweight (LBW/HBW).

METHODS AND FINDINGS

We used 2-sample mendelian randomization (MR) with 81 single-nucleotide polymorphisms (SNPs) instrumenting for a lifelong predisposition to insomnia. Our outcomes included ever experiencing stillbirth, ever experiencing miscarriage, GD, HDP, perinatal depression, PTB (gestational age <37 completed weeks), LBW (<2,500 grams), and HBW (>4,500 grams). We used data from women of European descent (N = 356,069, mean ages at delivery 25.5 to 30.0 years) from UK Biobank (UKB), FinnGen, Avon Longitudinal Study of Parents and Children (ALSPAC), Born in Bradford (BiB), and the Norwegian Mother, Father and Child Cohort (MoBa). Main MR analyses used inverse variance weighting (IVW), with weighted median and MR-Egger as sensitivity analyses. We compared MR estimates with multivariable regression of insomnia in pregnancy on outcomes in ALSPAC (N = 11,745). IVW showed evidence of an association of genetic susceptibility to insomnia with miscarriage (odds ratio (OR): 1.60, 95% confidence interval (CI): 1.18, 2.17, p = 0.002), perinatal depression (OR 3.56, 95% CI: 1.49, 8.54, p = 0.004), and LBW (OR 3.17, 95% CI: 1.69, 5.96, p < 0.001). IVW results did not support associations of insomnia with stillbirth, GD, HDP, PTB, and HBW, with wide CIs including the null. Associations of genetic susceptibility to insomnia with miscarriage, perinatal depression, and LBW were not observed in weighted median or MR-Egger analyses. Results from these sensitivity analyses were directionally consistent with IVW results for all outcomes, with the exception of GD, perinatal depression, and PTB in MR-Egger. Multivariable regression showed associations of insomnia at 18 weeks of gestation with perinatal depression (OR 2.96, 95% CI: 2.42, 3.63, p < 0.001), but not with LBW (OR 0.92, 95% CI: 0.69, 1.24, p = 0.60). Multivariable regression with miscarriage and stillbirth was not possible due to small numbers in index pregnancies. Key limitations are potential horizontal pleiotropy (particularly for perinatal depression) and low statistical power in MR, and residual confounding in multivariable regression.

CONCLUSIONS

In this study, we observed some evidence in support of a possible causal relationship between genetically predicted insomnia and miscarriage, perinatal depression, and LBW. Our study also found observational evidence in support of an association between insomnia in pregnancy and perinatal depression, with no clear multivariable evidence of an association with LBW. Our findings highlight the importance of healthy sleep in women of reproductive age, though replication in larger studies, including with genetic instruments specific to insomnia in pregnancy are important.

Exploring and mitigating potential bias when genetic instrumental variables are associated with multiple non-exposure traits in Mendelian randomization

With the increasing size and number of genome-wide association studies, individual single nucleotide polymorphisms are increasingly found to associate with multiple traits. Many different mechanisms could result in proposed genetic IVs for an exposure of interest being associated with multiple non-exposure traits, some of which could bias MR results. We describe and illustrate, through causal diagrams, a range of scenarios that could result in proposed IVs being related to non-exposure traits in MR studies. These associations could occur due to five scenarios: (i) confounding, (ii) vertical pleiotropy, (iii) horizontal pleiotropy, (iv) reverse causation and (v) selection bias. For each of these scenarios we outline steps that could be taken to explore the underlying mechanism and mitigate any resulting bias in the MR estimation. We recommend MR studies explore possible IV-non-exposure associations across a wider range of traits than is usually the case. We highlight the pros and cons of relying on sensitivity analyses without considering particular pleiotropic paths versus systematically exploring and controlling for potential pleiotropic or other biasing paths via known traits. We apply our recommendations to an illustrative example of the effect of maternal insomnia on offspring birthweight in UK Biobank.

Human fertility and sleep disturbances: A narrative review

INTRODUCTION

Many factors may be hidden behind the global fertility decline observed in Western countries. Alongside the progressively increased age of infertile couples, environmental and behavioural factors, including non-optimal lifestyle habits, should be considered. Among these, sleep disorders have been suggested to be linked to human fertility.

METHODS

This is a narrative review, describing first sleep physiology, its disturbances, and the tools able to quantify sleep dysfunction. Then, we consider all available studies aimed at investigating the connection between sleep disorders and human fertility, providing a comprehensive view on this topic.

RESULTS

Forty-two studies investigating the relationship between sleep habits and human reproduction were included. All the published evidence was grouped according to the aspect of human fertility considered, i.e. i) female reproductive functions, ii) male reproductive functions, iii) natural conception and iv) assisted reproduction. For each of the sub-groups considered, the connection between sleep dysregulation and human fertility was classified according to specific sleep characteristics, such as sleep duration, quality, and habits. In addition, possible physio-pathological mechanisms proposed to support the link between sleep and fertility were summarized.

CONCLUSION

This review summarizes the most relevant findings about the intricate and still largely unknown network of molecular pathways involved in the regulation of circadian homeostasis, to which sleep contributes, essential for reproductive physiology. Thus, many mechanisms seem correlate sleep disorders to reproductive health, such as adrenal activation, circadian dysregulation, and genetic influences. This review highlights the need to properly designed trials on the topic.

Impact of sleep patterns upon female neuroendocrinology and reproductive outcomes: a comprehensive review

Sleep is vital to human bodily function. Growing evidence indicates that sleep deprivation, disruption, dysrhythmia, and disorders are associated with impaired reproductive function and poor clinical outcomes in women. These associations are largely mediated by molecular-genetic and hormonal pathways, which are crucial for the complex and time sensitive processes of hormone synthesis/secretion, folliculogenesis, ovulation, fertilization, implantation, and menstruation. Pathologic sleep patterns are closely linked to menstrual irregularity, polycystic ovarian syndrome, premature ovarian insufficiency, sub/infertility, and early pregnancy loss. Measures of success with assisted reproductive technology are also lower among women who engage in shift work, or experience sleep disruption or short sleep duration. Extremes of sleep duration, poor sleep quality, sleep disordered breathing, and shift work are also associated with several harmful conditions in pregnancy, including gestational diabetes and hypertensive disorders. While accumulating evidence implicates pathologic sleep patterns in impaired reproductive function and poor reproductive outcomes, additional research is needed to determine causality and propose therapeutic interventions.

Men's Sleep Quality and Assisted Reproductive Technology Outcomes in Couples Referred to a Fertility Clinic: A Chinese Cohort Study

BACKGROUND

Poor sleep quality has been linked to lower semen quality, but it is unclear whether this result in decreased fertility. To address this question, we retrospectively evaluated the relationship between men's sleep quality and treatment outcomes in subfertile couples receiving assisted reproductive technology (ART).

PATIENT ENROLLMENT AND METHODS

From September 2017 to November 2019, 282 subfertile couples referred to a Chinese fertility clinic and eligible for ART procedures were enrolled in our study. Sociodemographic characteristics, life habits, and sleep habits in the year prior to ART were recorded. Sleep quality was measured using the Pittsburgh Sleep Quality Index (PSQI). We first divided the patients into two groups based on sleep quality (good sleep: PSQI < 5 and poor sleep: PSQI ≥ 5). Then, the ART outcomes (fertilization rate, good quality embryo rate, implantation rate, positive pregnancy rate, clinical pregnancy rate, live birth rate, miscarriage rate, and birth weight) of each group were analyzed. Finally, multivariate linear and logistic regression analysis were used to examine the relationship between sleep quality (discrete variable or dichotomous variable) and ART outcomes.

RESULTS

The participants in the poor sleep group showed a lower fertilization rate of 60.13% (543/903) when compared with 67.36% for the good sleep group (902/1339), P < 0.001. The global PSQI score had a significant influence on birth weight (β, -63.81; 95% CI, -119.91- -8.52; P = 0.047), and live birth rate (OR, 0.88; 95% CI, 0.78- 0.99; P = 0.047) after adjusting for the interfering factors. Men's sleep quality was unrelated to good quality embryos rate, implantation rate, positive pregnancy rate, clinical pregnancy rate, or miscarriage rate.

CONCLUSION

Men's sleep quality was positively associated with fertilization rate, birth weight, and live birth rate among couples undergoing ART.

Sleep Behavior and Self-Reported Infertility: A Cross-Sectional Analysis Among U.S. Women

OBJECTIVE

To investigate the associations between sleep behaviors and female infertility.

METHODS

We conducted a cross-sectional study composed of 2175 U.S. women 18-44 years of age from the National Health and Nutrition Examination Survey (NHANES) (2015-2018). Bedtime/waketime and sleep duration were extracted from the sleep disorder questionnaire. Self-reported infertility was defined as a binary variable based on the participants' response to the question, "Have you ever attempted to become pregnant over a period of at least a year without becoming pregnant?". Multivariate logistic regression analyses were done to explore the relationship between sleep behaviors and female infertility.

RESULTS

Bedtime (OR=1.24; 95% CI, 1.10-1.40, P = 0.001) and waketime (OR=1.14; 95% CI, 1.01-1.28, P = 0.037) were associated with infertility. Waketime of 08:00 was the inflection point, above which the probability of infertility increased rapidly (OR=1.41; 95% CI, 1.11-1.79, P = 0.004). Sleep-wake behavior was significantly associated with infertility (OR=1.34; 95% CI, 1.16-1.53, P < 0.001) and participants with early-bed/early-rise behavior had the lowest risk.

CONCLUSIONS

Among U.S. women 18-44 years of age, bedtime and waketime were significantly linearly and non-linearly correlated with infertility, respectively. Early-bed/early-rise behavior was associated with the lowest infertility rate. Further study is needed because the timing of sleep behaviors are modifiable factors and could be a novel strategy to cope with infertility.

The potential impacts of circadian rhythm disturbances on male fertility

A circadian rhythm is an internalized timing system that synchronizes the cellular, behavioral, and physiological processes of organisms to the Earth's rotation. Because all physiological activities occur at a specific time, circadian rhythm disturbances can lead to various pathological disorders and diseases. Growing evidence has shown that the circadian clock is tightly connected to male fertility, and circadian perturbations contribute to infertility. The night shiftwork, insufficient sleep, and poor sleep quality are common causes of circadian disturbances, and many studies have reported that they impair sperm quality and increase the risk of male infertility. However, research on the impacts of light, body temperature, and circadian/circannual rhythms is relatively lacking, although some correlations have been demonstrated. Moreover, as the index of sperm quality was diverse and study designs were non-uniform, the conclusions were temporarily inconsistent and underlying mechanisms remain unclear. A better understanding of whether and how circadian disturbances regulate male fertility will be meaningful, as more scientific work schedules and rational lifestyles might help improve infertility.

Circadian Clock-Controlled Checkpoints in the Pathogenesis of Complex Disease

The circadian clock coordinates physiology, metabolism, and behavior with the 24-h cycles of environmental light. Fundamental mechanisms of how the circadian clock regulates organ physiology and metabolism have been elucidated at a rapid speed in the past two decades. Here we review circadian networks in more than six organ systems associated with complex disease, which cluster around metabolic disorders, and seek to propose critical regulatory molecules controlled by the circadian clock (named clock-controlled checkpoints) in the pathogenesis of complex disease. These include clock-controlled checkpoints such as circadian nuclear receptors in liver and muscle tissues, chemokines and adhesion molecules in the vasculature. Although the progress is encouraging, many gaps in the mechanisms remain unaddressed. Future studies should focus on devising time-dependent strategies for drug delivery and engagement in well-characterized organs such as the liver, and elucidating fundamental circadian biology in so far less characterized organ systems, including the heart, blood, peripheral neurons, and reproductive systems.

Unraveling the Balance between Genes, Microbes, Lifestyle and the Environment to Improve Healthy Reproduction

Humans’ health is the result of a complex and balanced interplay between genetic factors, environmental stimuli, lifestyle habits, and the microbiota composition. The knowledge about their single contributions, as well as the complex network linking each to the others, is pivotal to understand the mechanisms underlying the onset of many diseases and can provide key information for their prevention, diagnosis and therapy. This applies also to reproduction. Reproduction, involving almost 10% of our genetic code, is one of the most critical human’s functions and is a key element to assess the well-being of a population. The last decades revealed a progressive decline of reproductive outcomes worldwide. As a consequence, there is a growing interest in unveiling the role of the different factors involved in human reproduction and great efforts have been carried out to improve its outcomes. As for many other diseases, it is now clear that the interplay between the underlying genetics, our commensal microbiome, the lifestyle habits and the environment we live in can either exacerbate the outcome or mitigate the adverse effects. Here, we aim to analyze how each of these factors contribute to reproduction highlighting their individual contribution and providing supporting evidence of how to modify their impact and overall contribution to a healthy reproductive status.