Blue light has a dark side

What is blue light? The effect blue light has on your sleep and more.

Updated: August 13, 2018 Published: May, 2012 Harvard Health Letter

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 pretty much for granted.

But we may be paying a price for basking in all that light. At night, light throws the body’s biological clock—the circadian rhythm—out of whack. Sleep suffers. Worse, research shows that it may contribute to the causation of cancer, diabetes, heart disease, and obesity.

What is blue light?

Not all colors of light have the same effect. Blue wavelengths—which are beneficial during daylight hours because they boost attention, reaction times, and mood—seem to be the most disruptive at night. And the proliferation of electronics with screens, as well as energy-efficient lighting, is increasing our exposure to blue wavelengths, especially after sundown.

Light and sleep

Everyone has slightly different circadian rhythms, but the average length is 24 and one-quarter hours. The circadian rhythm of people who stay up late is slightly longer, while the rhythms of earlier birds fall short of 24 hours. Dr. Charles Czeisler of Harvard Medical School showed, in 1981, that daylight keeps a person’s internal clock aligned with the environment.

Is nighttime light exposure bad?

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 (it’s very preliminary) that lower melatonin levels might explain the association with cancer.

A Harvard study shed a little bit of light on the possible connection to diabetes and possibly obesity. The researchers put 10 people on a schedule that gradually shifted the timing of their circadian rhythms. Their blood sugar levels increased, throwing them into a prediabetic state, and levels of leptin, a hormone that leaves people feeling full after a meal, went down.

Even dim light can interfere with a person’s circadian rhythm and melatonin secretion. A mere eight lux—a level of brightness exceeded by most table lamps and about twice that of a night light—has an effect, notes Stephen Lockley, a Harvard sleep researcher. Light at night is part of the reason so many people don’t get enough sleep, says Lockley, and researchers have linked short sleep to increased risk for depression, as well as diabetes and cardiovascular problems.

Effects of blue light and sleep

While light of any kind can suppress the secretion of melatonin, blue light at night does so more powerfully. Harvard researchers and their colleagues conducted an experiment comparing the effects of 6.5 hours of exposure to blue light to exposure to green light of comparable brightness. The blue light suppressed melatonin for about twice as long as the green light and shifted circadian rhythms by twice as much (3 hours vs. 1.5 hours).

In another study of blue light, researchers at the University of Toronto compared the 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. It also suggests that shift workers and night owls could perhaps protect themselves if they wore eyewear that blocks blue light. Inexpensive sunglasses with orange-tinted lenses block blue light, but they also block other colors, so they’re not suitable for use indoors at night. Glasses that block out only blue light can cost up to $80.

LED blue light exposure

If blue light does have adverse health effects, then environmental concerns, and the quest for energy-efficient lighting, could be at odds with personal health. Those curlicue compact fluorescent lightbulbs and LED lights are much more energy-efficient than the old-fashioned incandescent lightbulbs we grew up with. But they also tend to produce more blue light.

The physics of fluorescent lights can’t be changed, but coatings inside the bulbs can be so they produce a warmer, less blue light. LED lights are more efficient than fluorescent lights, but they also produce a fair amount of light in the blue spectrum. Richard Hansler, a light researcher at John Carroll University in Cleveland, notes that ordinary incandescent lights also produce some blue light, although less than most fluorescent lightbulbs.

Protect yourself from blue light at night

  • Use dim red lights for night lights. Red light has the least power to shift circadian rhythm and suppress melatonin.
  • Avoid looking at bright screens beginning two to three hours before bed.
  • If you work a night shift or use a lot of electronic devices at night, consider wearing blue-blocking glasses or installing an app that filters the blue/green wavelength at night.
  • Expose yourself to lots of bright light during the day, which will boost your ability to sleep at night, as well as your mood and alertness during daylight.

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https://www.health.harvard.edu/staying-healthy/blue-light-has-a-dark-side

Why is Magnesium so Important?

Magnesium is important in your daily diet because your body requires it for so many different functions. We can quickly become deficient in this important mineral if we are not consuming enough high magnesium foods. Magnesium plays a role in over 300 enzymatic reactions within the body, including the metabolism of food. Magnesium is also required in fat synthesis, protein synthesis, and the transmission of nerve impulses. Magnesium is necessary for muscle relaxation and energy production.  In the adult body, bones contain approximately 60% of all magnesium, and most of the remainder is contained in muscles and soft tissues.

At least half of the US population is not getting enough magnesium in their daily diet and inadequate magnesium intake is associated with increased diabetes risk.  The typical American diet is low in vegetables and whole grains, resulting in reduced magnesium intake.  The Recommended Daily Allowance (RDA) for magnesium is 310-320 mg/day for adult women and 400-420 mg/day for adult men.  Recent research (The Nurses’ Health Study (NHS), NHS2 and Health Professionals’ Follow-Up Study), reveals that higher magnesium intake is associated with lower risk of type 2 diabetes, particularly in diets with poor carbohydrate quality.

A deficiency of magnesium may be involved in many conditions, including:

Asthma

Cardiovascular disease

Type 2 Diabetes

Fatigue

Fibromyalgia

High blood pressure

Hypoglycemia

Insulin Resistance

Migraines

Osteoporosis

Premenstrual syndrome

Stroke

Magnesium can help you with:

Relieving constipation

Calming nerves and anxiety

Relaxing muscles

Easing insomnia

Improving insulin sensitivity

Bone health

Increasing energy

Relieving migraine headaches

Where will you find Magnesium? Green leafy vegetables, unrefined whole grains, and nuts and seeds are richest in magnesium.  Meats, yogurt and milk also contain a moderate amount. Refined foods, like carbohydrates, are poor sources of magnesium.  There are various websites including The U.S. Department of Agriculture’s, which list the nutrient content of many foods and provide comprehensive lists of foods containing magnesium arranged by nutrient content and by food name.

Should you supplement with Magnesium?  Magnesium supplements are available, but it is best to obtain any vitamin or mineral through food, because nutrients work better when synergistically combined with other nutrients. Check with your doctor before taking any supplements.

 

When Should You Buy Organic?

Each year the Environmental Working Group publishes their updated “Shopper’s Guide to Pesticides in Produce”.  EWG is a nonprofit organization that advocates for policies that protect global and individual health.  Their Shopper’s Guide is based on results of more than 35,200 samples of produce tested by the U.S. Department of Agriculture and Food and Drug Administration. Their guide helps consumers to reduce their exposure to toxic pesticides. They rank the pesticide contamination of 48 popular fruits and vegetables.  The produce is tested for pesticide residues after it has been thoroughly washed and prepared to be eaten.  Their “Dirty Dozen” list notes those fruits and vegetables with the highest pesticide residues.  It is important to buy organic when purchasing from this list of produce.  Their “Clean Fifteen” list notes the least contaminated fruits and vegetables.  These are safer choices of conventionally grown produce.  Use this guide to provide easy-to-use advice when shopping for your favorite fruits and vegetables.