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”

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4445839/  

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

https://academic.oup.com/aje/article/177/10/1027/101677 - 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: 

 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5402839/ - 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. 

https://www.fertstert.org/article/S0015-0282(01)03254-X/fulltext 

“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:

• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6391306/ 429 women in a cohort study were tested and found that women who work cyclical shifts have an increased risk of pre-term labour 

• https://www.researchgate.net/publication/256076771_Shift_Work_and_Circadian_Dysregulation_of_Reproduction This study shows that shiftwork induces circadian dysynchrony during pregnancy resulting in lower birth weights. In general shiftwork during pregnancy is also associate with higher risk of miscarriage. 

Research 

• Why we sleep by Matthew Walker 

• Articles as linked above

Cover Image by Sarah Richter from Pixabay