Sleep and Fertility: What’s the Connection?

Sleep and fertility are closely linked. Circadian rhythms play an important role in this connection. Circadian rhythms are internal body clocks that control our sleep-wake cycle, body temperature, and hormone production. When your sleep and/or circadian rhythms are disrupted, it can have a negative impact on your physical and mental health which can affect fertility. 

But disrupted rhythms and poor sleep might also impact fertility directly. What might be the underlying mechanism for this?

Healthy sleep

Most adults need between seven to nine hours of sleep per night. While you sleep, your body and brain do all the necessary, nightly repair and maintenance work. This supports your physical health and cognitive function. When you wake up feeling refreshed and ready to go the next morning, you know that your sleep did its job. 

Some people naturally prefer to go to bed early, while others prefer to go to bed later at night. Sleep timings are set by your body clock, a group of cells towards the middle of your brain which are responsible for the generation of a plethora of circadian (daily) rhythms in your body. In an ideal world, where you are free of any societal demands, you follow your body’s innate rhythm, and sleep at the time that is right for you and for as long as you need.

Unhealthy and mistimed sleep

Unfortunately, modern humans don’t always sleep at the times their body clock wants them to sleep. Even if we do, many of us report poor quality sleep. An unhealthy lifestyle, work, and social factors can lead to disturbed and/ or mistimed (e.g. irregular) sleep. Up to 30% of the adult population experience acute sleep problems, most of whom are women.

What has become apparent in the recent years is not only has there been a rise in sleep problems but also a rise in fertility problems. This has led researchers wondering whether one causes the other or if indeed there is a bidirectional relationship between the two. More data is urgently needed but the picture that is beginning to emerge suggests that disrupted sleep, i.e. poor quality or mistimed sleep, can contribute to fertility issues. And that picture also suggests that the stress and anxiety related to conceiving while perhaps also undergoing IVF can disrupt sleep.

How sleep and circadian rhythms might affect fertility?

There are several ways in which sleep and circadian rhythms can affect fertility.

First, in women, mistimed sleep and a lack of sleep can lead to changes in the production of hormones that are essential for reproduction, such as estrogen and progesterone. 

Second, sleep deprivation can increase levels of stress hormones.These hormones include cortisol which not only make you feel more alert in the moment, over time they can also interfere with ovulation and implantation. 

Third, sleep deprivation can disrupt the body’s natural temperature rhythm, which is important for sperm production. Lack of sleep lowers testosterone levels, which, in turn, reduces sperm production and sex drive in men.

In addition, shift work and jet lag can also disrupt circadian rhythms and lead to fertility problems. Shift workers are more likely to have irregular menstrual cycles and difficulty conceiving. Jet lag can also disrupt the body’s natural sleep-wake cycle and lead to fertility problems.

What you can do to look after your sleep to improve fertility

If you are trying to conceive, it is important to make sure that you are getting enough sleep and that your circadian rhythms are not disrupted. Here are some tips for improving your sleep and circadian rhythms:

• Establish a regular sleep schedule and stick to it as much as possible, even on weekends. To find out what your personal sleep schedule is, stop using electronic devices in the evening and see when you start to feel sleepy. If possible, set your alarm to as late as possible and see when you wake up naturally
• Create a relaxing bedtime routine. This could include taking a warm bath, reading a book, or listening to calming music. Basically, do something that you enjoy (just not staring at your phone)
• Make sure your bedroom is dark, quiet, and cool
• Avoid caffeine from 2pm onwards. If you drink alcohol, limit how much you drink and when
• Get regular exercise, but not too close to bedtime
• See a sleep specialist or doctor if you have chronic sleep problems

By following these tips, you can improve your sleep and circadian rhythms and increase your chances of getting pregnant.

Here are some additional research findings on the relationship between sleep, circadian rhythms, and fertility:

• A study in the journal Fertility and Sterility found that women who slept less than 6 hours per night were more likely to have difficulty conceiving than women who slept 7-8 hours per night
• A study in the journal Epidemiology found that shift workers were more likely to have irregular menstrual cycles and difficulty conceiving than people who worked regular hours

In conclusion

If you are concerned about the impact of sleep or circadian rhythms on your fertility, talk to a sleep coach, or your GP. They can help you develop a plan to improve your sleep and circadian rhythms and increase your chances of getting pregnant.

References:

Vargas, I., Nguyen, A. M., Muench, A., Bastien, C. H., Ellis, J. G., & Perlis, M. L. (2020). Acute and Chronic Insomnia: What Has Time and/or Hyperarousal Got to Do with It?. Brain sciences, 10(2), 71. doi.org/10.3390/brainsci10020071 

Willis, S. K., Hatch, E. E., Wesselink, A. K., Rothman, K. J., Mikkelsen, E. M., & Wise, L. A. (2019). Female sleep patterns, shift work, and fecundability in a North American preconception cohort study. Fertility and sterility, 111(6), 1201–1210.e1. doi.org/10.1016/j.fertnstert.2019.01.037 

Lawson, C. C., Whelan, E. A., Lividoti Hibert, E. N., Spiegelman, D., Schernhammer, E. S., & Rich-Edwards, J. W. (2011). Rotating shift work and menstrual cycle characteristics. Epidemiology (Cambridge, Mass.), 22(3), 305–312. doi.org/10.1097/EDE.0b013e3182130016