How Sleep may Impact Fertility: The Science Behind Circadian Rhythm & Fertility

It seems we need regular sleeping and eating schedules to keep all of our clocks in sync. Studies show that if we mess with the body's natural sleep-wake cycle — say, by working an overnight shift, taking a transatlantic flight or staying up all night with a new baby or puppy — we pay the price. - Allison Aubrey on NPR


We all know that lack of sleep can make us grumpy and less productive, but did you know that lack of sleep can also impact fertility? Here we examine the role circadian rhythm plays in hormone production and tips on how to achieve healthy sleep habits for hormonal health.


A recent study that researched 120,000 women who perform shift work lends insight into the extent of how much sleep impacts fertility. The study revealed that women who work night shifts had an 80% higher rate of fertility issues, including a significantly more difficult time conceiving and a higher risk of having a miscarriage (source).


Why does this happen? Researchers have not yet pinpointed the exact cause, but experts believe that circadian rhythm is involved. Your internal clocks tell your body when to start and stop numerous biochemical functions at specific times. Among the many things that these clocks control such as hair growth, appetite, and sleep, is hormone production. When your circadian rhythm is disrupted, it upsets these internal clocks and your body’s clock genes may cause biological changes that alter your hormone production (source).


Hormones affected by sleep in relation to fertility include melatonin, cortisol, progesterone, estrogen, luteinizing hormone (LH) and follicle-stimulating hormone (FSH). With chronically shortened sleep cycles or night shift work, these hormones get out of wack and may not only cause ovulation to be compromised, but also pregnancy complications.


Lack of sleep has also been shown to cause weight gain, which is another risk factor for infertility (source). Leptin, for example, affects both weight gain and ovulation. If a woman is not getting enough sleep or works night shifts, leptin production is compromised, which may cause irregular menstrual cycles and increased appetite. 


Your internal clock functions based off of cues from light and dark sources as well as your eating schedule. If you are crossing time zones, like taking a vacation to Hawaii from New York or stay out late at a concert, you will disrupt your circadian rhythm, but your body will reset within a couple of days. Regular disruptions, however, may eventually lead to fertility issues. If you are not sleeping well, your circadian rhythm will be disrupted and therefore, perhaps your hormone production (source).

Ok, so if you don’t sleep well, you might be thinking, "Thanks a lot! Now I’ll be even more stressed if I can’t sleep!” Don't worry, following sleep hygiene tips can make a world of a difference.


Follow these steps to keep your circadian rhythm in balance:


  • Everyone is different but aim for 7-9 hours of sleep each night. It is possible to get too much sleep, so do not sleep longer than 9 hours.
  • Go to bed and wake up around the same time every day including weekends plus or minus 20 minutes.
  • Turn off all electronics a couple of hours before going to sleep. If this isn’t realistic, try downloading an application that changes the light on your screens. If that still is not working, then be sure to start a new habit of turning off electronics an hour before bedtime - it will be worth it for your health. 
  • If you can’t sleep, don’t panic. Get up and go to another room, but keep lights off and no electronics. Sit in the dark and try deep breathing until you get sleepy.
  • No matter how tired you are in the morning, do not push snooze. Try not to nap, unless sick or course.  If you feel that you must nap, it shouldn’t be for any longer than 30 minutes.
  • Exercise daily, but not too close to bedtime. Try exercising before 2 pm.
  • Avoid caffeine, alcohol, and cigarettes. Talk to your doctor to see if any of your medications interfere with your sleep.
  • Start a relaxing bedtime routine and do not snack two hours before bedtime. Dim the lights and keep your bedroom cool (source).
  • Try eating your main meal earlier in the day and avoid eating snacks late at night which may confuse your internal clocks.
  • Travel across time zones frequently?  Try the guidelines by Harvard Health to minimize jet lag and see if that resets your internal clock. Check it out here