Dec 08

Blue light, circadian rhythms and your sleep

Having trouble sleeping?

The cause may be staring at you right now! Your monitor, iPhone, tablet PC or TV may be the cause. Read this article to find out why.


The problem of biological time

Our bodies are very sophisticated organisms, that need to coordinate and organize biological activities:

  • Feeding
  • Hormonal cycles
  • Cell division
  • DNA repair

Many of these activities are accomplished within  a 24 hour cycle, referred to as circadian rhythm. All life on earth, from the lowest bacteria to humans exhibit some form of this rhythm. Our bodies have to have a way to keep this cycle aligned with daylight for optimal health.

Why is circadian rhythm important?

Different organ systems must coordinate and work together to sustain life. This is done by various biological clocks within your body. There is one master clock – the suprachiasmic nucleus, and other clocks. The clocks in the body are there to tell what biological time it is. For example, it may be time to feed, and you may feel your stomach growling. Or it may be time to sleep, and you will feel sleepy.

If clocks are out of alignment, the body “falls apart”:

  • Hormones, like cortisol secretion are improperly timed
  • Genes are activated at wrong times.
  • DNA damage occurs due to repair in daylight

A host of conditions, diseases and symptoms that come and go, appears.  These are caused by disturbances in circadian rhythm and the overall chronobiology of the body. If your internal clocks are poorly aligned,  your health is poor. But if they are working together, the body has a chance to repair itself.

If you still don’t believe me, think of a 4 cylinder drive car that runs on only 3 cylinders. One of them is misfiring. The car’s engine shakes, roars, and does not output quite as much power as it should. While it may be possible to drive a car around a corner to a mechanic, you won’t take such car on a highway, and prolonged operation at 3/4 cylinders would result in permanent damage. The body is a much more sophisticated machine.

How is circadian rhythm regulated?

Cold-blooded creatures rely on temperature to determine what time of day it is – when it’s warm, lizards become active, but humans maintain consistent body temperature and cannot rely on external temperature cues to know what time it is. This is why humans, as most other warm blooded mammals rely on sunlight to keep their biological clocks properly synchronized.

Melanopsin, a specialized pigment within human eyes responds to blue light and sends signal to the master clock within the human body that it is day. In particular, Melanopsin responds most strongly to 420 nanometer true blue light, like the color of this sentence. Additional wavelengths, up to 480 nanometers also affect it.  When melanopsin detects blue light, it sends a signal to Suprachiasmatic nucleus  within the human brain to signal daylight. Suprachiasmic nucleus has a lot of functions related to regulating the circadian rhythm in humans.

Blue light is everywhere at night!

I live in United States of America, and the color Blue is very popular here. This color is literally everywhere, from the cans of coke in a supermarket to 12% of cars to the color of hyperlinks in this article. Blue is a very good, pleasing color to use during the day, because the clear sky is blue.

The following groups of people work during the day. They plan and build during the day, when blue is good.

  • People who build software, like windows and web browsers
  • People who create websites and run advertising campaigns on the internet
  • People who run TV programs
  • People who conduct research and  focus groups
Content produced by such people is viewed at all times of the day. It is most frequently viewed on light-emitting devices, meaning it radiates white light containing the 420-480 nanometer blue spectrum:
  • Televisions
  • Computer Monitors
  • Smartphones and tablet PCs
  • Fluorescent lights and compact fluorescent lightbulbs
  • Even some night lights and alarm clocks!

The color blue is very bad for you when seen at night!

Recall that your eyes have a special pigment melanopsin, which most strongly responds to 420 nanometer light wavelength. This pigment sends information directly to your brain’s  Suprachiasmatic nucleus. This tiny part of your brain is “dumb”, but has a lot of responsibility. So when it sees blue, it triggers and maintains activities that are associated with wakefulness.

This is very bad if you are about to go to sleep, because you will get only a fraction of the true restorative power of sleep you need. So if you want to sleep 8 hours, but turn off the computer just 15 minutes before bed, chances are you wont be getting 8 hours of quality sleep!

This is very true for me, because I have to sleep for 10+ hours at less than 50 % efficiency, and still feel like crap, unless I turn off the computer a couple hours before bed… Which I do, occasionally.


Using Computers, smartphones and TVs at night

A typical 3.5 inch iPhone can radiate up to 200 lumens of light. There have been studies that determined that such amount is enough to trigger changes in sensitive individuals, if the screen is observed at night.

An iPad is much larger, and has already been proven to negatively affect sleep in people

Most 17 and 19 inch computer monitors today do not automatically adjust brightness, meaning that you are looking at about 4 iPads worth of white light.

Any big screen TV is a monster – just turn off the light in a room and look at your walls, you will see what color light it is shedding.

Good sleep hygiene practices recommend turning off these devices a couple hours before bed. Do any of us follow these practices?


Compact Fluorescent Ligthbulbs use 420 nanometer blue!

I was a big fan of Compact Fluorescent Lightbulbs (CFL) when they first arrived. I’m going green! I’m saving energy, I thought. Yes, but it’s still bad for you!

No, it’s not just mercury or disposal issues. Take a look at the graph on the right. It compares the

  • “old school”  incandescent lighbulb that your parents used(left side)
  • and  the modern equivalent – compact fluorescent (right side)

Notice the huge spike at around the number 400 for the fluorescent lightbulb. More precisely, this number is 420 nanometers – the exact wavelength that tells your brain it is day.

Because your brain may be confused by these lights, it is best not to use them at night. Try to avoid using CFL bulbs before bed – they will confuse your sleep regulation.


Quick fixes don’t work!

  • Blue light in the 420 nanometers is here to stay.
  • You won’t give up your monitors, TVs, iPads before bed.
  • Software manufacturers are unlikely to act, unless sued for major money.
  • Compact fluorescent lightbulbs are here to stay.

And so people seek quick fixes to circadian rhythm disorders and misadjustments, while the numbers of ever-fatigued, depressed, bipolar and insomnia users seem to rise. Quick fixes to these problems include:

  • Sleeping pills
  • Sleeping aids and placebos
  • Melatonin, a sleep promoting hormone
  • A “night cap” – using alcohol to knock the body out
  • Abuse of cold medicines like Nyquil, which are intended for short term use
People want sleep, and they are getting it any way they can! I myself have used melatonin for over 9 years now, tried sleeping pills, and still suffer from insomnias due to computer use. All of these quick fixes are like clobbering a confused brain into submission. “SLEEP! NOW! I COMMAND THEE!!!”- insomniac to the brain
Forcing the brain to sleep when it cannot, is not ready to is not good in the least. The brain adapts, compensates, but the quality of sleep is still low. For example, when alcohol is used to induce sleep, the brain’s restorative Rapid Eye Movement sleep is suppressed until the effects of alcohol wear out. Then the brain “rebounds” and dreams like crazy. Well, maybe it is crazy at that time!


Permanent Solution? Eliminate blue before bed!

Sounds simple, right? Just turn off all devices and chill out.  Well, if you are like me, you won’t give up hours of entertainment. If you like to save energy, you will keep the compact fluorescent lightbulbs. So what’s the way out? I can think of these things:

  • Read, and light your room with incandescent(old school) light bulbs and reduce overall light intensity with light dimmers

    These glasses claim to block blue light of the appropriate frequency

  • Install F.Lux, a software to make your monitor less blue
  • Turn off additional monitors if you have more than one
  • Watch TV on your tablet PC, not on a monstrous plasma screen before bed.
  • Wear Blue Light Blocking sunglasses like Blublocker( Amazon affiliate link).

Unfortunately this is not a bandaid or short term fix for the problem. It is likely that these solutions would have to become permanent, meaning ever single day you reduce the amount of blue light that confuses your sleep centers. I bought myself the Blublocker sunglasses and intend to keep wearing them before bed.


Blue light blocking in action – the image loses blue color and appears yellow. This is different from the typical sunglasses or shades.