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When It’s Smart to Be in the Dark

When It’s Smart to Be in the Dark

Research has shown sleeping in a dimly lit—instead of dark—environment is associated with disruption of circadian rhythm (your internal body clock) and neuroendocrine physiology (how your nerves and hormones work together). This can trigger insomnia (related to mood shifts and weight gain) and accelerate tumor growth. One Israeli study even found that women living in neighborhoods where it was bright enough to read a book outside at midnight had a 73 percent higher risk of developing breast cancer than those who lived in areas with the least outdoor artificial light.

And now researchers have found the health disruption from light pollution might get passed down through generations. A recent lab study found that when hamsters are exposed to an unnatural mix of daylight and darkness it can cause epigenetic changes that alter both male and female’s biochemistry. Then, when they mate, their offspring end up with weakened immune systems and impaired endocrine activity.

Our advice:

  • Shut off the TV and digital devices when you turn off the lights.
  • Buy blackout curtains/blinds to keep ambient light out of bedrooms.
  • Use only red wavelength light in your bathroom.
  • Wear a sleep mask.

Medically reviewed in January 2020.

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