Circadian Rhythm and Hormones: Why Night Shifts Wreck Periods

Topic: Sleep science

Women who work night shifts or have erratic schedules (nurses, flight attendants, freelancers) have significantly higher rates of infertility and irregular periods.

This is because your Circadian Rhythm (Body Clock) is directly tied to your Endocrine System (Hormones).

The Pathway

1. Light enters the eye.
2. Suprachiasmatic Nucleus (SCN): The master clock in the brain gets the signal.
3. Melatonin: If it is dark, Melatonin rises. Melatonin is a powerful antioxidant that protects eggs from damage.
4. Cortisol: If it is light at 2 AM, Cortisol rises. High cortisol suppresses progesterone.

The Fix for Shift Workers

You cannot quit your job. But you can hack the light.

1. The “fake” Sunset

When you finish your shift (even if it is 8 AM), wear Blue Light Blocking Glasses on the way home. Trick your brain into thinking it is “evening” so you can sleep.

2. Blackout Curtains

Your bedroom must be pitch black. Even a tiny sliver of light from a streetlamp can disrupt melatonin. Tape over LEDs on the AC unit.

3. Anchor Meals

Try to eat your meals at the same time every day, regardless of when you sleep. Metabolic regularity helps anchor the body clock.

Light is not just for seeing. It is biological information. Control the input.