Humans are designed on a circadian rhythm — the internal cycle that includes the tendency to sleep when it is dark and wake up when the sun comes up. The circadian rhythm also governs the flow of hormones, temperature fluctuations, and other things we may not consciously notice about our bodies.
At night — in the dark — is when melatonin comes out to play in our bodies. Research shows that melatonin is one of the body’s most powerful cancer fighters! All cells, including cancerous cells, have melatonin receptors. When melatonin latches on to a cell, it slows cell division — this is good news for cancerous cells, which can divide and reproduce very rapidly.
Things that mess with your circadian rhythms — like working the night shift, or leaving the television on all night — can interrupt your body’s melatonin activity. This can raise your risk of certain types of cancer. Data from the Nurses’ Health Study at Harvard Medical School shows that nurses who worked on the night shift for most of their careers had a 36% higher rate of breast cancer than those who worked mainly on the day shift.
So how much light at night does it take to throw off your circadian rhythms and interrupt melatonin’s good work? Researchers aren’t exactly sure yet. They do know that light at the blue end of the spectrum — like fluorescents and halogens — are the worst for your melatonin.
Sticking to a healthy circadian rhythm isn’t impossible!
- Keep your bedroom as dark as possible. Turn the nightlight off! Don’t leave a light on in the hallway. And if outside light is coming in, consider switching to heavier, room-darkening shades, blinds, or drapes.
- Use a dim bulb. If you wake up in the middle of the night, don’t immediately go for the brightest lights possible. Use a low light if you need to move around, but give yourself a chance to drift back to sleep before you pull out a book.
- For your midnight bathroom runs, use a red light. The red light end of the spectrum has the least effect on melatonin.
- Get some sunshine in the morning. Bright light resets your circadian rhythms — ten or fifteen minutes of bright sunlight in the morning can help set your brain’s clock.
- Get more sunshine as you age! Your eyes are the pathway to the gland that runs your brain’s master clock. Eye changes as you age mean you may not be getting enough bright light to set your brain’s clock.