Researchers in a 2022 study compared sleep characteristics for women of different ages, and found that women who slept 7-9 hours a night, and had good quality sleep, had optimal IVF outcomes.
There isn’t much data on the subject of sleep and IVF outcomes. Some studies have found that disturbed sleep is associated with decreased AMH (Wang et al. 2021) and a higher risk of infertility (Auger et al. 2021). There is also evidence that sleep disturbances can affect the number of retrieved oocytes (Lyttle et al. 2018). But besides that, there really isn’t much information on sleep and IVF!
In this summary, we’ll take a look at a study by Yao et al. (2022) who wanted to know how sleep patterns can influence IVF outcomes. This prospective study took place in China at a single IVF center between 2018 and 2019. A total of 1276 patients were enrolled and took a questionnaire on the day of retrieval about their sleep characteristics for the last month.
🔗 Original studies are referenced in this post or within the linked Remembryo posts.
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IVF outcomes and sleep characteristics
In terms of sleep duration, they found that women who slept <7 hours a night retrieved 11.5% fewer eggs, and 11.9% fewer mature eggs, compared to women who slept 7-8 hours a night. Women who slept a bit longer at 9-10 hours showed no change in their egg numbers but had about a 35% decrease in clinical pregnancy rate. That’s a lot! Interestingly, those who slept >10 hours had no change in pregnancy rates, although the >10 hour data set was smaller so this might explain it.
Quality of sleep matters too! Women who reported their sleep quality as “poor” had a 20% lower fertilization rate compared to those with “good” sleep quality.
Falling asleep can be a real challenge for some people. Women who had trouble falling asleep 3 or more times a week had 10.5% fewer mature eggs, 14.8% fewer normal 2PN embryos (so there were more 1PN or 3PN abnormal fertilizations), and 15.1% fewer good quality embryos compared to women who reported <3 times a week.
The time you go to bed also seems to be important based on this study. They found that women’s “mid-sleep time” affected fertilization rates. This is the half-way point between the time you fall asleep and the time you wake up, and is basically a measure of what time you go to bed. For those who sleep around 8 hours, women who went to bed too early (earlier than around 10 pm) or too late (after 11 pm), saw about a 12-13% decrease in fertilization rates.
What about night shift? Women who reported having night shift experience (defined as working between 12 am and 8 am) had a 30% decrease in implantation rates.
So from this data, the best outcomes were from women who slept about 7-9 hours, went to bed around 10 pm and woke around 6 am, had good sleep quality, and didn’t have trouble falling asleep.
Sleep quality and age matter for optimal IVF outcomes
The kind of sleep pattern in the previous section works best on average for the whole group, but what about those with good quality vs poor quality of sleep, or women aged <30 or >30? They found that women who reported good sleep quality needed less sleep for optimal outcomes compared to women with poor sleep quality. Similarly, women <30 needed less sleep for optimal outcomes compared to women >30.
I’ll put some numbers to this to make more sense of it, but realize that this data has a fairly wide range outside of the 7-9 hours (which is what ~70% of women reported in this study). This is due to the smaller sample size for the <7 hour (81 women, 6.3%) and >10 hour (73 women, 5.7%) groups. All this means is that the numbers reported below can vary from person to person. A bigger sample size is needed to narrow it down.
Anyways! I’m pulling these numbers from the graphs that are in the paper, so they’re approximations.
Good quality sleepers needed less sleep for optimal outcomes:
- 6 hours: ~6 good quality embryos, ~75% fertilization.
- 9 hours: ~5 good quality embryos, ~73% fertilization.
- 12 hours: ~5 good quality embryos, ~72% fertilization.
Poor quality sleepers needed more sleep for optimal outcomes:
- 6 hours: ~4 good quality embryos, ~65% fertilization.
- 9 hours: ~6 good quality embryos, ~72% fertilization.
- 12 hours: ~8 good quality embryos, ~78% fertilization.
Women <30 needed less sleep for optimal outcomes:
- 6 hours: ~70% implantation rate, ~70% pregnancy rate.
- 8 hours: ~65% implantation rate, ~60% pregnancy rate.
- 10 hours: ~55% implantation rate, ~50% pregnancy rate.
Women >30 needed more sleep for optimal outcomes:
- 6 hours: ~65% implantation rate, ~60% pregnancy rate.
- 8 hours: ~70% implantation rate, ~67% pregnancy rate.
- 10 hours: ~75% implantation rate, ~72% pregnancy rate.
Conclusions
Overall this study found that women who sleep about 7-9 hours a night, go to bed around 10 pm (and wake around 6 am), and had a good quality of sleep, tended to perform best in terms of IVF outcomes. Additionally, they found that women who reported good sleep quality needed less sleep for optimal outcomes compared to women with poor sleep quality. Similarly, women <30 needed less sleep for optimal outcomes compared to women >30.
So why all the fuss about sleep quality/length/timing? It may have to do with a disturbance in circadian “clock” genes. Circadian rhythms are physiological and behavioral changes that follow a 24-hour cycle. Think of how we get tired at night and wake up during the morning. There are a set of genes that influence this behavior, and they’re triggered to some degree by environmental cues like day and night.
These genes and how they’re “turned on” (expressed) oscillate in 24 hour rhythms. The proteins produced by this gene expression can regulate other clock genes, or other unrelated genes. Disturbances in sleep can alter these rhythms, and this can have biological consequences like what we see in this study.
One hormone you’ve probably heard of is melatonin. This hormone (produced by the pineal gland) can regulate the expression of clock genes to influence sleep-wake rhythms. Melatonin is also an antioxidant and plays a role in oocyte development (Tamura et al. 2012). Disturbed sleep patterns might alter melatonin levels and this can have an impact on oocyte development, as well as leaving the oocyte more sensitive to oxidative stress and damage. Mejlhede at al. (2021) performed a meta-analysis and found a higher mature oocyte count in those who supplemented with melatonin (but unfortunately without a significant increase in pregnancy rates).
A limitation is that this study makes use of self-reported data, which may not be totally accurate.
More studies will need to be done among different centers to confirm these findings, and preferably with a more diverse group of women to better match the general population.
Reference
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About Embryoman
Embryoman (Sean Lauber) is a former embryologist and the founder of Remembryo, an IVF research and fertility education website. After working in an IVF lab in the US, he returned to Canada and now focuses on making fertility research more accessible. He holds a Master’s in Immunology and launched Remembryo in 2018 to help patients and professionals make sense of IVF research. Sean shares weekly study updates on Facebook, Instagram, and Reddit regularly. He also answers questions on Reddit or in his private Facebook group.
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IVF and pregnancy outcomes for women 45+
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Examining live birth rates in IVF cycles with 5 or less follicles