Tip of the Month

Although it is environmentally friendly, blue light can affect your sleep and potentially cause disease.
Until the advent of artificial lighting, the sun was the major source of lighting, and people spent their
evenings in (relative) darkness. Now, in much of the world, evenings are illuminated, and we take our
easy access to all those lumens for granted. But we may be paying a price for basking in all that light.

At night, light throws the body’s biological clock out of whack. Not only does sleep suffer, but research
shows that it may contribute to the causation of cancer, diabetes, heart disease, and obesity.

Not all colours of light have the same effect. Blue wavelengths seem to be the most disruptive at night.
And the proliferation of electronics with screens is increasing our exposure to blue wavelengths,
especially after sundown.

Everyone has slightly different circadian rhythms (or biological clocks), but the average length is 24 ¼
hours. The circadian rhythm of people who stay up late is slightly longer, while the rhythms of early risers
fall short of 24 hours. Daylight keeps a person’s internal clock aligned with the environment.

Some studies suggest a link between exposure to light at night, such as working the night shift, to some
types of cancer, diabetes, heart disease, and obesity. That’s not proof that nighttime light exposure causes
these conditions; nor is it clear why it could be bad for us. But we do know that exposure to light
suppresses the secretion of melatonin, a hormone that influences circadian rhythms, and there’s some
experimental evidence that lower melatonin levels might explain the association with cancer.

While light of any kind can suppress the secretion of melatonin, blue light at night does so more
powerfully. In a study of blue light, researchers at the University of Toronto compared melatonin levels of
people exposed to bright indoor light who were wearing blue-light-blocking goggles to people exposed to
regular dim light without wearing goggles. The fact that the levels of the hormone were about the same in
the two groups strengthens the hypothesis that blue light is a potent suppressor of melatonin.

To protect yourself from blue light at night, use dim red lights for night lights, avoid looking at bright
screens within three hours of going to bed, and expose yourself to lots of bright light during the day – this
will boost your ability to sleep at night as well as your mood and alertness during the day!

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