Can Blue Light Cause Depression?

Can Blue Light Cause Depression?

Blue light effects

Yes, in humans, there is evidence that supports that blue light disrupts the normal circadian rhythms (biological clock), resulting in mood disorders such as depression. Although blue wavelength light potentially contributes to health problems associated with circadian disruption, research has not conclusively demonstrated that blue wavelength light exposure at night causes an increase in these health risks. The following are a few common benefits and harmful effects of blue light

  • Disruption of circadian rhythm: A circadian rhythm is a natural, internal process that regulates the sleep-wake cycle and repeats with each rotation of the earth, roughly every 24 hours. It can refer to any biological process that displays an endogenous, entrainable oscillation of about 24 hours.
  • Digital eye strain syndrome: It involves blurry vision, difficulty focusing, dry/irritated eyes, headaches, neck and back pain.
  • Cancers: Greater risk of breast and prostate cancer.
  • Health problems: People with long-term blue light exposure may have an increased risk of diabetes, heart disease and obesity.
  • Mood disorders: People who are exposed to constant blue light may have an increased risk of depression and other mood disorders.
  • Eye problems: May contribute to macular degeneration and cause permanent eye damage.

Research carried out at Oregon State University suggests that extensive daily exposure to blue light may accelerate aging by effectively damaging retinal cells (helps to see), brain neurons (helps to think) and the locomotive system (helps to move). This may happen even if we don’t absorb the blue light directly through the eyes, but simply from exposing the skin to it at home and at work where it’s emitted from various household fixtures and devices.

Beneficial effects of blue light

  • It’s well documented that some blue light exposure is essential for good health. Research has shown that high-energy visible light boosts alertness, helps memory and cognitive function and elevates mood.
  • Not all blue lights are bad. Light therapy is used to treat seasonal affective disorder, which is a type of depression related to changes in seasons. Its symptoms usually begin in the fall and continue through the winter. The light sources for this therapy emit a bright white light that contains a significant amount of blue light rays.
  • It’s best to be exposed to blue light outside. Sunlight is the best source to get it. Getting natural sun exposure nurtures the suprachiasmatic nucleus or SCN (the biological rhythm pacemaker in the brain) when blue light is combined with other wavelengths of light from the spectrum.
  • Minimum exposure to morning blue light contributes to better hormone levels, body temperature and digestion.
  • Efficient exposure to natural blue light may also play an important role in eye health and reduce the risk of conditions such as myopia (nearsightedness).


  • Blue light can help elevate mood and boost awareness.
  • However, long-term or frequent exposure to blue light at night can lower the production of melatonin, which is the hormone that regulates sleep and disrupts the circadian rhythm.
  • Researchers aren’t exactly sure why exposure to blue light at night seems to have such detrimental effects on our health, but it is known that exposure to light suppresses the secretion of melatonin. The lower melatonin levels might explain the association with the above health problems.
  • Exposure to blue light during daytime hours helps maintain a healthy circadian rhythm. However, too much blue light late at night (for example, reading a novel on a tablet, computer or e-reader at bedtime) can disrupt this cycle, potentially causing sleepless nights and daytime fatigue.
  • While blue light is great for our bodies during the day when we take it in from the sun, most problems occur at night because we unknowingly expose ourselves  to blue lights inside our homes.
  • In the brain, a small group of hypothalamic nerve cells (the suprachiasmatic nucleus or SCN) function as a master circadian pacemaker. This controls the timing of the sleep-wake cycle and coordinates this cycle with other brain and body systems to direct behavior appropriately.
  • When we expose ourselves to blue light at night by using gadgets, such as smartphones, we are telling our brains that the sun is still up. This is how we mess with our circadian rhythm. Circadian rhythms are important because they determine the sleeping and eating patterns of all animals, including humans.
  • Blue light can also affect our mental health and this seems to be particularly true for younger people. Early exposure to electronics has been named as one of the possible reasons behind the phenomena. According to another recent study, children’s eyes absorb more blue light than adults from digital device screens, making children even more susceptible to harm from blue lights.

Medically Reviewed on 3/30/2021


Medscape Medical Reference

Royal Society Te Aparangi