Nurses, midwives, police officers, paramedics, hospitality and more all have one thing in common, working night shifts.
An aspect of the job they don’t typically mention on orientation day is the disruption to the circadian rhythm that happens when working night shift, and how this impacts metabolism, cellular function, hormones, menstrual cycles and the health of the reproductive system.
The circadian rhythm is our ingrained sleep/wake cycle that influences every cell in the body. It is governed by two main hormones; cortisol and melatonin.
Cortisol levels rise as the day begins and helps us wake up and get going. Cortisol ebbs and flows throughout the day and wanes as the sun sets and night time approaches. Melatonin is then released at nighttime to help with a deep restful sleep and cellular repair throughout the night. Put simply, cortisol should be higher during the day and lower at night, and melatonin should be low during the day and high at night time.
When working night shift (or just being awake at night and sleeping more during the day), this pattern flips, and the body is needing to release cortisol at night time and trying to secrete melatonin during the day to attempt a restful sleep. This process over time can lead to inflammation and impact metabolism. Melatonin is also a key antioxidant for the body that has a particular affinity with nourishing the ovaries, supporting ovarian health and assisting in the production of hormones FSH and LH (critical for the menstrual cycle that you can read more about here).
When the circadian rhythm is becoming dysregulated, some common menstrual cycle parameters that can be impacted is timing of ovulation, luteal phase length and even period pain. Egg quality and fertility can also be impacted.
Do you work night shift? Have you noticed any irregularities in your menstrual health?
Next we will explore some things you can do as a shift worker to support your hormonal health!