Health Consequences of Nighttime Light Exposure

Did You Know…nighttime light exposure can be seriously detrimental to your health?

Nighttime light exposure can cause serious problems, according to a study just published in the journal Current Biology.  “We showed that the absence of environmental rhythms leads to severe disruption of a wide variety of health parameters,”said author Johanna Meijer of Leiden University Medical Center in the Netherlands.

Amazingly, Meijer’s research indicates that limiting your nighttime light exposure could be just as impactful as eating right and being physical active.

Why Your Circadian Rhythm Matters 

For the study, mice were exposed to light around the clock for twenty-four weeks while Meijer and a team of scientists, including Eliane Lucassen, tracked changes to various indicators of health.  They found that constant light exposure reduced the normal rhythmic patterns in the brain’s central circadian pacemaker of the suprechiasmatic nuclei (SCN) by 70%.

In other words, nighttime light exposure dramatically disrupted their circadian rhythm.

You may know that your circadian rhythm helps determine your sleep cycle, but did you know that it also determine a number of other important physiological processes?  The researchers found that a skewed circadian rhythm led to…

  • Reduced skeletal muscle function
  • Loss of bone mass
  • Elevated levels of inflammation
Essentially, when their circadian rhythms were disrupted, the mice became frailer.

The Widespread Impact of Nighttime Light Exposure 

These findings make it clear that overexposure to light can do significant damage.  The risks are especially grave for older individuals and those whose health is already compromised.  Statistics show that nighttime light exposure affects three-quarters of the world’s population, and round-the-clock light exposure is extremely common in nursing homes and intensive care units.

“We used to think of light and darkness as harmless or neutral stimuli with respect to health,”Meijer said.  “We now realize this is not the case.” She and her team intend to conduct a deeper analysis of the impact of nighttime light exposure on the immune system.  They also plan to examine the health benefits of balanced exposure to light and dark for patients.

Undoing Damage Done by Nighttime Light Exposure  

It’s not too late to reverse the consequences of nighttime light exposure.  Meijer and her colleagues found that after just 2 weeks of a balanced light-dark cycle, the negative effects on health caused by overexposure to light reversed!

For most of us, some exposure to light at night will be unavoidable.  But there are factors you can control, such as turning off the lights before falling asleep, and limiting your use of light-emitting electronics such as phones, tablets, computers, and TVs.  Another option is to wear amber-lensed goggles—research indicates that these can mitigate the effects of nighttime light exposure.