The Role of Restorative Sleep in Fertility

Discover the link between sleep and your ability to conceive. From hormones to internal clocks, stress and inflammation, let us deep dive into the science behind it all.

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The vital role of restorative sleep and fertility

Sleep is a fundamental and biological necessity that plays a vital role in maintaining overall health and well-being. Adequate, restorative sleep is especially crucial for individuals who are trying to conceive, as it has a profound impact on fertility.

Restorative sleep, scientifically known as slow-wave or deep sleep [1], is unlike other stages of the sleep cycle. During this phase, our bodies go into overdrive; repairing and rejuvenating. Recent research reveals that during deep sleep, your brain waves slow down, allowing for the consolidation of memories, tissue repair, and the release of growth hormones crucial for tissue growth and repair [2].

So, what’s the connection between deep sleep and fertility? Studies have shown that deep sleep plays a central role in the regulation of the endocrine system, which is responsible for hormone production [3]. Hormones like luteinising hormone (LH) and follicle-stimulating hormone (FSH), crucial for reproductive health, are intricately tied to the sleep-wake cycle. Additionally, during restorative sleep, the stress hormone cortisol, which can disrupt reproductive hormones, is effectively regulated. It’s this orchestration of hormone regulation during restorative sleep that has a profound effect on fertility and overall well-being. Let’s take a further dive in.

Hormonal imbalances

Hormones are the body’s messengers, coordinating a vast array of physiological processes. As mentioned above, the endocrine system is the body’s master regulator and ensures that hormones are produced, released, and maintained to homeostatic levels to support reproductive functions. When sleep is insufficient or disrupted, it can set in motion a chain of events that can lead to hormonal imbalances with far-reaching consequences for fertility.

Now, let’s refer back to cortisol. In normal, healthy circumstances, cortisol follows a diurnal rhythm, peaking in the morning to help us wake up and then gradually declining as the day progresses, However, inadequate or disrupted sleep can lead to the dysregulation of cortisol production. Studies have observed that sleep disturbances can result in elevated cortisol levels throughout the day. This perpetual state of heightened stress hormones can throw the entire endocrine system off balance [3].

When it comes to fertility, LH and FSH are paramount in regulating the menstrual cycle, ovulation, and the health of the reproductive organs. Disrupted cortisol levels can interfere with the secretion of LH and FSH, leading to irregular menstrual cycles, anovulation, and a host of other fertility issues. Research also demonstrates that when cortisol levels are persistently elevated due to poor sleep, LH and FSH levels may decrease or become irregular, creating a challenging environment for successful conception [3].

Circadian rhythms

Our bodies have internal biological clocks known as circadian rhythms, which govern various bodily functions, including the timing of hormone production. Sleep is intricately linked to these rhythms, and disruptions can have significant negative outcomes. In women, irregular sleep patterns can lead to irregular menstrual cycles [4], making it more challenging to predict ovulation and conceive. Men, on the other hand, may experience decreases in sperm quality and testosterone levels when circadian rhythms are disrupted.

Stress & Inflammation

The ongoing stress associated with poor sleep can also lead to chronic inflammation, a process that poses a significant threat to reproductive health. Inflammatory responses, whether triggered by external factors or internal stressors, can disrupt the functioning of the reproductive organs in multiple ways.

For example, chronic inflammation may interfere with the fallopian tube’s ability to capture and transport eggs, impair the uterus’ ability to support a fertilised embryo or create an unfavourable environment for sperm survival and motility [5]. Additionally, the presence of chronic inflammation can lead to structural changes in the reproductive organs, impacting both fertility and overall health. Check out the study published in Toxicology Reports, which explores the multifaceted effects of inflammation on fertility, highlighting the importance of a balanced and healthy immune response in reproductive success [6].

Insulin Resistance

Emerging research suggests that lack of restorative sleep is associated with insulin resistance, a condition where the body’s cells become less responsive to insulin [7]. This condition can have implications for fertility, particularly in women, as it is linked to metabolic disorders such as polycystic ovary syndrome (PCOS), which can affect the regularity of menstrual cycles and overall reproductive health.

So, how do we get more restorative sleep?

Now that we’re well across the importance of restorative sleep in fertility, how do we go about optimising our sleep? Here are a few things I have personally been experimenting with and tracked improvements with a wearable health/sleep device (I use Oura).

1. Establish a consistent sleep schedule: Go to bed and wake up at the same time every day - even on weekends! This helps to regulate your circadian rhythm.

2. Limit screen exposure before bed: As a full-time student with a job that requires a lot of time on a device, I get how hard this is (I spend more time on my laptop than I’d feel comfortable admitting). But I cannot stress enough how detrimental blue light from devices is for your sleep. It not only interferes with your ability to fall asleep but has also been shown to interfere with the amount of restorative sleep [8].

3. Watch your evening meals: Avoid large meals, caffeine, and alcohol close to bedtime as this can interfere with sleep quality. Try not to consume caffeine at least 6 hours prior to bedtime.

4. Include movement throughout the day: Engaging in regular physical activity can promote restorative sleep [9]. However, avoid strenuous exercise close to bedtime.

As with any change in habit, it takes time and consistency. It is essential to create a healthy sleep routine and environment that suits your individual needs and preferences.

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Disclaimer

This content is not intended as medical advice and should not be used to diagnose, treat or prevent any disease or health illness. Please consult a qualified healthcare professional before acting on any information presented here.

Further reading:

[1] Dijk, J. (2009). Regulation and Functional Correlates of Slow Wave Sleep. Journal of Clinical Sleep Medicine : JCSM : Official Publication of the American Academy of Sleep Medicine, 5(2 Suppl), S6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2824213/

[2] Brinkman, J. E., Reddy, V., & Sharma, S. (2023). Physiology of Sleep. StatPearls [Internet]. https://www.ncbi.nlm.nih.gov/books/NBK482512/

[3] Kim, T. W., Jeong, H., & Hong, C. (2015). The Impact of Sleep and Circadian Disturbance on Hormones and Metabolism. International Journal of Endocrinology, 2015. https://doi.org/10.1155/2015/591729

[4] Baker, F. C., & Driver, H. S. (2007). Circadian rhythms, sleep, and the menstrual cycle. Sleep Medicine, 8(6), 613-622. https://doi.org/10.1016/j.sleep.2006.09.011

[5] Weiss, G., Goldsmith, L. T., Taylor, R. N., Bellet, D., & Taylor, H. S. (2009). Inflammation in Reproductive Disorders. Reproductive Sciences (Thousand Oaks, Calif.), 16(2), 216. https://doi.org/10.1177/1933719108330087

[6] Ojo, O. A., Nwafor-Ezeh, P. I., Rotimi, D. E., Iyobhebhe, M., Ogunlakin, A. D., & Ojo, A. B. (2022). Apoptosis, inflammation, and oxidative stress in infertility: A mini review. Toxicology Reports, 10, 448-462. https://doi.org/10.1016/j.toxrep.2023.04.006

[7] Hirotsu, C., Tufik, S., & Andersen, M. L. (2015). Interactions between sleep, stress, and metabolism: From physiological to pathological conditions. Sleep Science, 8(3), 143-152. https://doi.org/10.1016/j.slsci.2015.09.002

[8] Silvani, M. I., Werder, R., & Perret, C. (2022). The influence of blue light on sleep, performance and wellbeing in young adults: A systematic review. Frontiers in Physiology, 13. https://doi.org/10.3389/fphys.2022.943108

[9] Uchida, S., Shioda, K., Morita, Y., Kubota, C., Ganeko, M., & Takeda, N. (2012). Exercise Effects on Sleep Physiology. Frontiers in Neurology, 3. https://doi.org/10.3389/fneur.2012.00048

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