How does your sleep affect your fertility?

How does your sleep affect your fertility?

The book ‘Why we sleep’ by Matthew Walker discusses the effect of Sleep loss on Obesity, the reproductive system, the immune system - pretty much everything. 

For the purposes of this post, I’m just going to summarise the impact of lack of sleep on your fertility. 

If you’re trying for a baby you probably want to maximise your chances of conception and having a healthy child that is full term. The best thing you can do is eat well and sleep well. 

Study 1 

A research group at the University of Chicago took a group of healthy young men in their mid 20s and only let them sleep for 5 hours a night for one week. They found the following results:

  • Drop in testosterone (compared to their levels when they were fully rested) 

  • “Daytime testosterone levels were decreased by 10% to 15% in this small convenience sample of young healthy men who underwent 1 week of sleep restriction to 5 hours per night, a condition experienced by at least 15% of the US working population. By comparison, normal aging is associated with a decrease of testosterone levels by 1% to 2% per year”  

Study 2 

According to Matthew Walker, Studies show that men who report that they don’t sleep much have: 

  • 29 percent lower sperm count than men getting a full night of sleep

  • Sperm have deformities

  • men who don’t sleep as much usually have smaller testicles than those who sleep well. 

  • feel tired and fatigued during the day

  • dulled libido

  • testosterone maintains bone density so may also affect their ability to build muscle and strength

This is the study on Sperm count if you want more info - Association of Sleep Disturbances With Reduced Semen Quality: A Cross-sectional Study Among 953 Healthy Young Danish Men

I also found another study of 981 Chinese men if you need more convincing: - Sleep Deprivation and Late Bedtime Impair Sperm Health Through Increasing Antisperm Antibody Production: A Prospective Study of 981 Healthy Men

Study 3 

Women and fertility 

  • sleeping less than six hours a night results in 20% drop in the hormone that makes women release follicles in their ovaries. 

“Nevertheless, over >300 cycles, we observed a 20% augmentation in FSH levels among long-time sleepers.” 

Study 4 

A report by Matthew Walker refers to talks about women working night shifts e.g. nurses found that poor sleep for women in these occupations had:

  • 33% higher rate of abnormal menstrual cycles than women doing normal day time work. 

  • Women who worked erratic hours are 80% more likely to suffer from issues that reduce their ability to get pregnant

  • women who do become pregnant and sleep less than 8 hours a night all the night are more likely to have a miscarriage in the first trimester compared to those who sleep 8 hours a night. 

While I couldn’t find this exact study online, I found some additional studies if you are interested:


  • Why we sleep by Matthew Walker 

  • Articles as linked above

Cover Image by Sarah Richter from Pixabay

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