Suppose you could go to any drugstore and purchase an over-the-counter product that could improve the quality of your sleep, your mental health and even your physical health.

Further, imagine that this product is inexpensive, free of side effects—and you only have to buy it once to achieve the benefits for the rest of your life.

The benefits of this unregulated product could include:

  • Lowered risk of depression, anxiety and Seasonal Affective Disorder
  • Lessened insomnia (if you happen to suffer from it).
  • Lessened inflammation from autoimmune diseases such as arthritis and asthma (If you are prone to such inflammation)
  • Increased resistance to infectious disease
  • Lowered risk of cancer
  • Improved cardiovascular health
  • Lowered risk of obesity and Type 2 diabetes

I don’t know about you, but if such a product existed, I’d call it a wonder drug.

Well, recent research into the neuroscience of circadian rhythms (how our nervous systems anticipate and adapt to light-dark cycles) suggest that such a wonder drug might actually exist, at a one-time price of about $20.

And the wonder “drug” is……..amber tinted sunglasses.

Eric Haseltine
Source: Eric Haseltine

Strange as it seems, recent studies at Harvard and elsewhere suggest that using amber-tinted sunglasses that block out artificial blue light at night could have the broad ranging benefits described.

I’ll explain the importance of amber and blue in a moment, but first, let me go into a little chrono-biology (science of biological clocks) to illuminate the subject of circadian rhythms.

We are walking clocks synchronized by light

To fully understand why blocking artificial blue light after sunset could have so many positive effects we have to go a few billion years into our evolutionary past, when our distant ancestors were single-celled organisms.  These ancient bacteria needed to “know” when the sun was shining in order to avoid replicating while harmful UV radiation from the sun would damage DNA during cell division. As a result, our earliest ancestors evolved internal 24 hour “circadian clocks” that would turn on cell division at night when harmful UV radiation would be absent.

As we evolved into multi-celled animals, circadian clocks retained their usefulness to time our wake-sleep cycles according to the ecological niches that our ancestors occupied.  As “diurnal” (daytime) creatures, our most recent ancestors were active during the day when their excellent eyesight could be used to greatest advantage and when they could avoid nocturnal predators such as wolves and big cats. Thus our ancestors needed an internal clock that told them when to be active and when to sleep.

The master clock that governed wake-sleep cycles in these mammalian ancestors was the suprachiasmatic nucleus (SCN) of the hypothalamus in the brain. This structure, which is present in modern humans-- receives direct input from special photo-sensors in our eyes, synchronizing our body rhythms to the ever-changing light-dark cycles of the seasons. For example, with the prolonged absence of light after sunset, the SCN promotes release of the neurotransmitters melatonin and serotonin, making us sleepy. In the winter months, with early sunsets and late sunrises, our ancestors likely slept earlier and rose later than in the summertime, when it made sense for them to be out and about longer  (to make hay while the sun shone, as it were).

The SCN also triggers changes in our metabolism and immune systems in order to prepare us for the day.  Because we are more likely to encounter threats while we’re awake, our stress (fight or flight) hormones kicks into gear when we wake, and so does our metabolism, to anticipate ingestion and breakdown of food.

Anticipating such daily events before they happen is better than reacting after they happen, because it takes time for our bodies to ramp up our immune systems, adrenal glands and metabolisms.

Just like boy scouts, evolution has decided that our bodies need to be prepared for changing conditions during each day.

Here is a schematic of a few of the normal 24 hour cycles that our bodies go through to prepare themselves for each day.

Eric Haseltine
Source: Eric Haseltine

Melatonin, which makes us sleepy, is normally secreted in the evening, based upon the amount of light we are exposed to. The greater the artificial light at night, the more delayed the increase in melatonin.

Fight-or-flight hormones, such as cortisol, normally peak after awakening, suppressing the body’s inflammatory responses. Cortisol exerts a powerful inhibitory effect on the immune system, so the amount of immune “pro-inflammatory” compounds and many types of immune cells normally peak in the evening when cortisol levels dip.  Excessive artificial light at night distorts this normal cycle, compromising immune function.

Glucose tolerance (how much our body can absorb sugar from the blood after a meal) also waxes and wanes with the circadian clock, peaking in daytime (when we customarily eat to get energy for the day) and dipping at night (when we rest, and need much less energy). Thus, people who eat late at night (such as shift workers), have higher levels of blood glucose after a meal than people who eat an identical meal during the day or early evening.

The importance of eliminating blue-light exposure at night

From this discussion, it’s clear that our metabolisms, immune systems and stress-response systems normally have a regular SCN-driven daily cycle. Research shows that when we throw this cycle out of whack with shift work, jet lag or excessive exposure to artificial light at night our immune systems, metabolisms and stress response systems become active when they shouldn’t be active and inactive when they should be active.

Negative effects of shift work and excessive artificial light at night include

  • Insomnia and sleep disorders
  • Higher incidence of cancer, possibly due to under-performing immune systems  (healthy immune cells attack cancer cells).
  • Increased susceptibility to infection and auto-immune inflammatory diseases such as arthritis (when the immune system attacks healthy tissues, such as joints)
  • Higher incidence of obesity and diabetes, possibly related to lower glucose tolerance at night and other disruptions of normal metabolic cycles, such as breakdown of lipids.
  • Higher risk of cardiovascular disease (possibly triggered by increased obesity, diabetes and inflammation from over active immune systems)
  • Elevated risk of mood disorders such as depression and seasonal affective disorder (SAD)

For those of us who like to light up our homes, watch TV (or computer screens) at night, this is bad news indeed.

But here’s where the good news about amber tinted sunglasses comes in. Neuroscientists,  in separate studies  in Korea, Canada and at Harvard discovered that experimental subjects who wore tinted goggles that blocked out blue light:

  • Did not suffer from suppression of melatonin secretion near bedtime, and had melatonin levels throughout the day comparable to subjects who had only dim light or no light at night
  • Had improved mood
  • Had improved sleep quality

A more recent study in Norway demonstrated that blue-blocking glasses reduced the incidence of mania in subjects with bipolar disorder.

These results suggest that absence of blue light after sunset keeps the SCN in-synch with normal light-dark cycles, at least where melatonin release is concerned.

So what’s so special about blue light?

Well, as shown below, white artificial light, of the kind that radiates from indoor lamps, TV’s, mobile or computer screens contains all of the colors of the rainbow. The photo-receptive cells in the eye that excite our circadian clock (the SCN) respond most strongly to blue and blue green light. Thus, when blue/blue-green light is blocked by amber glasses, as shown below, the SCN only receives a small amount of neural excitation from the eye, creating conditions that—to the SCN—look like very dim illumination, akin to normal nighttime.

Eric Haseltine
Source: Eric Haseltine

Could such blue-light restriction also help our SCN sustain normal rhythms for immune function, stress hormones and metabolism, lowering the risks for infection, cancer, auto-immune disease, cardiovascular disease and diabetes?

Perhaps.

Based on a survey of research into the chrono-biology of health, the September 2015 Harvard Health Letter suggests that we can reduce health hazards of artificial light at night by using red lights to illuminate our home or workplaces, avoiding bright screens 3 hours before bedtime or using blue-blocking glasses. The Health Letter further recommends that we get ample sunlight or blue light during the day to double insure that we keep our SCN’s in synch.

Conclusions about the benefits of blocking blue light at night, although replicated across multiple experiments, are based on a relatively small  test populations, so further research is needed to establish just how robust the amber glass effect is. Also, additional research is needed to determine whether blue-blocking is as beneficial to our immune systems, metabolism and cardiovascular system as it seems to be for healthy melatonin, sleep cycles and bipolar disorder.

But even before the results of such studies come in, it could make sense to invest in amber tinted shades because-- unlike virtually every other over the counter or prescription treatment for insomnia, obesity, inflammation, cancer or cardiovascular disease-- sunglasses have no known side effects.

In other words, for a low cost, low risk investment, amber might keep you from feeling blue!

www.drhaseltine.com

References

https://www.ncbi.nlm.nih.gov/m/pubmed/16842544/

https://www.ncbi.nlm.nih.gov/m/pubmed/20030543/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2831986/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4734149/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3002207/

https://www.ncbi.nlm.nih.gov/m/pubmed/26584071/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4375372/

https://www.ncbi.nlm.nih.gov/m/pubmed/26375320/

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0067798

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4284776/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3781773/

http://www.pnas.org/content/112/17/E2225.figures-only

http://www.optimalhealthpartner.com/A_Archive/Anderson_LuxVsWavelength.pdf

https://www.ncbi.nlm.nih.gov/m/pubmed/10888476/

https://www.researchgate.net/publication/236931856_Crosstalk_between_the_circadian_clock_circuitry_and_the_immune_system

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3475279/

Chronobiol Int. 2015;32(9):1294-310. doi: 10.3109/07420528.2015.1073158. Epub 2015 Sep 16.

Effects of artificial light at night on human health: A literature review of observational and experimental studies applied to exposure assessment.

Cho Y1, Ryu SH1, Lee BR1, Kim KH1, Lee E2, Choi J1,2.

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

https://authoritynutrition.com/block-blue-light-to-sleep-better/

Obesity and metabolic syndrome: association with chronodisruption, sleep deprivation, and melatonin suppression.

Reiter RJ1, Tan DX, Korkmaz A, Ma S., Ann Med. 2012 Sep;44(6):564-77. doi: 10.3109/07853890.2011.586365. Epub 2011 Jun 13.

https://www.ncbi.nlm.nih.gov/pubmed/2722626 Light level and duration of exposure determine the impact of self-luminous tablets on melatonin suppression Wood B, Rea MS, Plitnick B, Figueiro MG.

J Pineal Res. 2006 Aug;41(1):73-8

Blue blocker glasses impede the capacity of bright light to suppress melatonin production.

Sasseville A Paquet N, Sévigny J, Hébert M.

., Appl Ergon. 2013 Mar;44(2):237-40. doi:

Amber lenses to block blue light and improve sleep: a randomized trial.

Burkhart K, Phelps JR. Chronobiol Int. 2009 Dec;26(8):1602-12. doi:

http://www.pnas.org/content/112/17/E2225.abstract

http://www.pnas.org/content/106/11/4453.full

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