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Nighttime Lighting and Your Health

In 2012 the American Medical Association (AMA) recognized that exposure to light at night, including from computer screens and other electronics, can disrupt circadian rhythms and sleep. It may also have other health impacts such as increased risk of certain cancers, diabetes, and mood disorders.

What is known?

Multiple studies have linked nighttime exposure to light to several types of cancer (e.g. breast, prostate), diabetes, heart disease, and obesity. It’s not yet exactly clear how or why it might be harmful, but it is known that exposure to light disrupts our ability to produce melatonin, a hormone that influences circadian rhythms, and there’s some preliminary research that links lower melatonin levels to cancer development.

Is all light the same?

While many kinds of light can suppress your body’s production of melatonin, blue light is the most suppressive. Blue wavelengths—which are beneficial during daylight hours because they boost attention and mood—seem to be the most disruptive at night. Blue light wavelengths are commonly emitted from energy-efficient LED and fluorescent lighting, as well as from laptops, tablets, and e-readers.

What can we do?

More research is needed to study the effects of blue-light exposure on sleep and overall health. Given the growing concerns with nighttime lighting, there are a few steps you can take to help manage nighttime light exposures and their potential associated health risks.  

  • Avoid looking at electronic displays and other bright light beginning two to three hours before bedtime.  
  • Other than unplugging from the electronic world at night, some alternatives include the following:
    • Wearing amber- or red-tinted glasses that are effective in filtering blue light.
    • Using computer software that changes the display color tone.
      • Some applications, such as F.lux, automatically adjust the color tone depending on the time of day.  
      • Mac and iOS devices have this software built-in called Night Shift.
  • Use dim red light for night lights, as it has the least power to shift circadian rhythm and suppress melatonin.

For more general tips relating to nighttime sleep hygiene, check out the US National Institute of Health - Centers for Disease Control and Prevention.