I do not sleep as well as I used to. Perhaps it is being tormented by guilt and worry combined with profound existential angst.

Or maybe it is my iPad. I gave up on most dead tree editions. I miss the smell and feel of books and magazines, but nothing is better than being able to increase the font size to 18. So I usually finish the day reading on the iPad.

I have noted programs that will remove the blue light from computer screen to aid in sleep. There is a night mode in iOS 9.3 and a program for the Mac I have on now that filter out the blue. Makes the screen oddly colored but it more restful on the eyes. I think. I am more in need of existential angst filter.

But what is the reality behind blue light as a source of sleeplessness? The Harvard Health Publications has an article on the topic warning of the hazards, and as a rule I have found the Harvard Health Publications to be distinctly gullible or useless when it comes to the more pseudo-scientific side of the tracks. I would suggest that advice such as:

Avoid looking at bright screens beginning two to three hours before bed.

Is great for the Amish but no so much for those who live in the modern world.

The issue is LEDs?

The white-light LED (i.e., the most common type of LED) is essentially a bichromatic source that couples the emission from a blue LED (peak of emission around 450–470 nm with a full width at half max of 30–40 nm) [4] with a yellow phosphor (peak of emission around 580 nm with a full width at half max of 160 nm) that appears white to the eye when viewed directly

And as they age LEDs may degrade becoming increasingly blue. Tell me about it. Been there, doing that.

Compared to fluorescent or incandescent light there is much more blue light in the spectrum of LEDs. And it turns out the blue light suppresses melatonin and has effects on the circadian rhythm. Next time your child asks “why is the sky blue?” you will have an answer. To keep us awake. And green light may put us to sleep.

iPads and their ilk produce lots of white, bright light and that means lots of blue, whether reading or playing Angry Birds and the use of electronic devices is associated with poor sleep.

Is it the blue light that results in poor sleep? In part:

Participants reading an LE-eBook took longer to fall asleep and had reduced evening sleepiness, reduced melatonin secretion, later timing of their circadian clock, and reduced next-morning alertness than when reading a printed book.

And the iPad?

Reading a story from an iPad decreased subjective sleepiness, delayed the EEG dynamics of slow wave activity by approximately 30 min, and reduced slow wave activity after sleep onset compared to reading from a book. No parameters of sleep state timing and sleep onset latency differed between the two reading conditions.

Does blue blocking help? Some hope against the data that it does:

The patients who used amber lens showed an advance of 78 min in DLMO value, although the change was not statistically significant (p = 0.145). Nevertheless, the sleep onset time measured by actigraph was advanced by 132 min after the treatment (p = 0.034).

And it is a consistent effect:

Sleep efficacy and sleep latency were significantly superior for wearers of the blue-light shield

There are no clinical trials of blue blocking software that alter the color of the screen.

Over all there is biologic plausibility and the studies, while few, small, and not of the highest quality, point in the same direction.

To summarize: The truth of blue light? Who cares?

I realize that progress is two steps forward and one step back, or perhaps 20 steps back. In league boots. And what is done one year can be undone the following. But we are at 400 ppm and rising and as a society we have decided in favor of a swan dive to the hard asphalt. The chance of mitigating a disastrous future for our children went from slim to none this week. While the thought leaders are trying for a win one for the Gipper moment, the pooch has been screwed.

I worry that, especially as the Millennium edges nearer, pseudoscience and superstition will seem year by year more tempting, the siren song of unreason more sonorous and attractive. Where have we heard it before? Whenever our ethnic or national prejudices are aroused, in times of scarcity, during challenges to national self-esteem or nerve, when we agonize about our diminished cosmic place and purpose, or when fanaticism is bubbling up around us – then, habits of thought familiar from ages past reach for the controls.

The candle flame gutters. Its little pool of light trembles. Darkness gathers. The demons begin to stir.

The candle is out. There is not even a small coal on the wick to fan to life. The demons rule. Game over.

No blue light filter will help.


Posted by Mark Crislip

Mark Crislip, MD has been a practicing Infectious Disease specialist in Portland, Oregon, since 1990. He is a founder and  the President of the Society for Science-Based Medicine where he blogs under the name sbmsdictator. He has been voted a US News and World Report best US doctor, best ID doctor in Portland Magazine multiple times, has multiple teaching awards and, most importantly,  the ‘Attending Most Likely To Tell It Like It Is’ by the medical residents at his hospital. His growing multi-media empire can be found at