The hot Blue Blocker Experiment

The eyes are the window through which light must pass, regardless of sightedness.

FACT: we don’t realize the importance of circadian biology.  Or at least we don’t act like it.  And we’re certainly not going to turn off our iPhones & laptops when we’re supposed to.  Potential intervention: hot Blue Blockers.  They’re a band-aid, no doubt, but they might help.  Jane Plain raised a potential concern with this here.  In brief, we can block blue light from molesting circadian biology with hot Blue Blockers, but extraocular light exposure could betray such feeble attempts.  I read something to a similar effect on Dr. Kruse’s blog.

It seems to be based, in part, on an experiment by Campbell & Murphy (1998).  They tried to experimentally screw circadia by exposing an isolated spot of skin on the back of the knee to 3 hours of bright light.  Melatonin data weren’t shown, but the authors said they mirrored body temperature:

Campbell Murphy

It worked (for body temperature, at least).

But FAR more interestingly, Czeisler showed bright light-induced melatonin suppression in blind people was reversed if they covered their eyes!!!Czeisler

This is wild.  Unless there is something CircadianlyMagical about the skin on the back of the knees, then these findings refute those of Campbell.  Czeisler’s findings were confirmed by Hatonen (1999) in sighted people: black circles = no light exposure; open squares = full-face light exposure with eyes closed (partially blunted melatonin secretion); and open circles = full-face light exposure with eyes open (fully blunted melatonin):Hatonen

Of note, blind eyes and closed eyes aren’t the same as covered eyes.  There were, however, 2 people who exhibited no melatonin inhibition with closed eyes.  Perhaps some are intrinsically more light-resistant, or have robust eyelids or something.

It seems as though we needn’t worry about Campbell’s findings after all because they were directly refuted by Hebert (1999):Hebert

The light exposure protocol in both of the studies was identical: 13000 lux to the back of the knees for 3 hours.


Perhaps we should’ve demanded to see Campbell’s melatonin data?  Or not.  Lushington confirmed Hebert’s findings (albeit with only 11000 lux):Lushington

In 2000, Lindblom blasted 10000 lux at a much larger surface area – chest & abdomen – and found no effect on melatonin:Lindblom

The eyes are the window through which light must pass, regardless of sightedness.

Was all of this blog post irrelevant until now?  Maybe. (sorry)

Sasseville compared bright light-induced melatonin suppression in people wearing boring shades (top graph) or hot Blue Blockers (SolarShield Orange Lenses) (bottom graph):


The orange lenses transmit slightly less light than the boring ones (32 vs. 52%), so they accounted for this by hitting the hot Blue Blockers with more lux (4000 vs. 2200… this is directly in their faces, so it couldn’t be >10000 lux like in the previous studies)… this still resulted in more irradiance hitting the hot Blue Blockers, so the odds were stacked against them (I think, #physics).

Lux: luminous flux per unit area
Irradiance: electromagnetic radiation per unit area

Melatonin suppression is important, but what we’re really talking about here is SLEEP.  And in 2009, Burkhart showed just that.  When assigned to hot Blue Blockers (NoIR Polycarbonate Lasershields), sleep quality markedly improved:


(granted, randomization was horribly bollixed, but it is what it is).

Sasseville came through again in 2009, this time for shift workers.  Their subjects had to wear hot Blue Blockers (Uvex Skypers) when they were leaving work [in the morning].   It worked.

Sasseville II

In sum, don’t sweat extraocular light exposure, and anyone with a metabolic disturbance who lives a remotely modernized existance, paleo or otherwise, might benefit from these.


calories proper


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hot Blue Blocker experiment: expectations = none.  I’m a “non-responder.”  This might not be the best time of year to conduct such an experiment, but the combination of high motivation and low patience prevailed.  And I still use my computer a lot at night.

This is a diary of sorts.
day 1: initial observations.
Started wearing them about 2 hours before sunset.  Outside sky prior to dusk looks like insane alien invasion.  But creepy red bathroom light looks exactly the same.  #physics.

Morning of day 2: Usually wake once or twice in the middle of the night, but didn’t…

Evening of day 2: Started rocking the shades 2 hrs prior to bedtime.  Same awesome yellow-ness and crisp resolution of the sunset.  It really looks like another planet.  I also could’ve probably stared directly at the sun with impunity (but didn’t).

Morning of day 3:  new conclusion: I think I usually wake up a few hours prior to dawn, but hot Blue Blockers prior has shifted this to a few hours earlier.

Morning of day 4:  same!  Hot Blue Blockers make me need to pee 4 hours sooner after falling asleep <– I’m a “responder!”
Mood, sleep quality, & energy levels stable <– “non-responder,” but willing to give it more time.  Burkhart’s study showed a near doubling of sleep quality, but it took 3 weeks.

P.S. FWIW, I’m wearing these, so definitely not going out in public places.

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  • Great post, Bill. With the addition of a bandana and some reflective phat pants, those specs immediately transform you into a Y2K raver.

  • George

    Very enjoyable read. But, I don’t want to wake up sooner – was this the effect you were trying for? Did you get back to sleep?

    • I honestly had zero expectations going into this. Totally exploratory. I’m not really bothered by midnight awakenings as I usually just check the time or go to the bathroom and fall right back to sleep…

      admittedly, I’m probably not the best subject for this kind of study; just hadn’t scratched the biohacker itch in a while.

      • Michael

        During the past week I’ve had no light exposure after dusk except 1 single candle or the fireplace on cold nights. Been going to bed around 10:30pm; then wide awake at around 3am! – and very hard to go back to sleep again. Not sure what’s going on there, but not exactly desirable.

        • Interesting! …almost seems like a form of jet lag.

          I’ll be the first to admit that circadia is highly nuanced and many aspects will be difficult to predict.

  • This blog needs to be more popular!

    Ability to suppress melatonin in response to light is indeed genetically variable and also dependant upon basal nervous system state at the time.

    For example it is a finding that people prone to bipolar disorder are much more sensitive to changes in melatonin secretion at the same room light intensity relative to people without bipolar. So, bipolar people would be supersuppressors of melatonin.

    Exaggerated suppression of melatonin in the presence of light is a marker for higher mood and nervous system activity; this is a marker as well for response to antidepressant therapies. People who aren’t necessarily bipolar, but merely depressed and trying to fix depression with antidepressant meds, will experience the same exaggerated melatonin suppression to light (which is a baseline risk for a bioplar person even taking no medication).

    Likely the ability to suppress melatonin from light is ultimately dependent upon other nervous system factors besides “light”, like responsiveness to serotonin, NE, and dopamine signalling, all of which are antagonized by melatonin and darkness. Dopamine and mel exist on an axis, so people with greater dopamine sensitivity / responsiveness (such as people prone to mania perhaps…) are more likely to experience this melatonin suppression.

    But yes, melatonin suppression at same light intensity is quite variable between people, or even the same people in different nervous system states (i.e. depressed people, though they have lower melatonin in general due to fubared neuroendocrine state, will not robustly respond to light with mel suppression which suggests good sensitivity/activity of 5ht/ne/dopamine).

    • In pretty much every study that showed data from each participant individually, there were a few “non-responders.” And in Lushington’s study, the huge error bars confirm the presence of super-responders & non-responders.

      Definitely warrants a subgroup analysis.

  • It would be fantastic if someone could invent blue blocker contact lenses. The idea of wearing glasses all day is not only impractical for me as an eyeglass user (I will not wear contacts later in day!) but contacts are more convenient/less distressing to people sensitive to physical irritation of contraptions on face.

    I am adept at seeing int he dark so I could merely remove the contacts and clean them right before sleep in semi-darkness.

    I also think contacts would work better as they would prevent trace light from escaping into eyes from around the frames.

    Either way I am totally getting blueblocker glasses. I have definitely observed wearing sunglasses home from work helps me sleep better and maintain circadian rhythm, so I imagine blue blockers do this only moreso. Do you have a recommendation?

    • Another problem with shift work is that as the shift ends and light begins to escalate (opposite of normal pattern) it may be imparing to job performance, or at least socially abnormal, to put on glasses while still at work.

      I suspect i could get away with it, but people like police might not.

      • you’re pretty good at this!

        I actually left out some of Sasseville’s data. Participants who were recruited during winter had to start wearing the glasses prior to leaving work, so they were given a weaker lens (Telemedoptique). The summer got Uvex Skypers and didn’t start wearing them until their shift was over.

    • Contact lenses are definitely coming. I kept reading the phrase “Blue-blocking IOLs” which turned out to be lenses that are actually implanted in the eyes during cataracts surgery… so regular contact lenses can’t be too far off.

      I’m using the UVEX Skypers. Cheap and from what I can tell, they do the job.

  • Jack Kruse

    Bill my quantum sleep blog that is coming soon gets into the optical science of what the newest intra ocular lenses are being constructed with to directly alter circadian clock genes. Luis DeLecea work on opticogenetics show that we can alter neural circuits with light. But the real key is developing a SQUID for blue light to stop the complex pathway of melatonin action. Soon you will see the stuff I left on Peter’s blog on transition metals is the key to this melatonin problem. Good blog. Enjoyed it.

    • Thanks, and looking forward to your quantum sleep blog.

      just saw this video with some of that tech – shoot a blue laser into the brains of some transgenic mice and they start ravenously feeding. Turn off the laser & voila, they stop eating on a dime:

      And a review by Dr. De Lecea on their optogenetics:
      Optogenetic investigation of neural circuits in vivo.

      It’s a game changer.

      • Jack Kruse

        I have been posting about this stuff for 3 yrs. No one sees what I see. So that makes me a target. But when you sit down and look at the science from a QED point of view, biology suddenly makes sense. There are so many enigma’s in medicine and biology we are stumped by. That is a signal to ask different questions. E=MC2 is the theory of everything in our universe. Making sense of it for biology is my passion. I think I am on the right path. Others may disagree but so far what I have been able to accomplish on me, my family and my patients is the exception and not the rule in medicine. That should get people more curious. I don’ find it that hard to understand because as a sick patient I became sick and tired of being sick and tired so I began to think and ask better questions. The answer was simple. Energy mass equivalence is multiplication. It is commutative property of math. Nuclear physics reads Einstein’s master piece left to right and biology reads it right to left. 2×3= 6. 3×2 still = 6……….your cells are giant semiconductors and you must pre load them all with energy…….if your gas tank is low your brain steal energy from other systems and when this happens it is called diseases…………if it lasts too long and you never fill up with gas you die early…….and your Ferrari fails because of the part of your car that requires the most energy…………It is the age old story of Robin Hood except biology style…………It is not that hard to get.
        We all need to get curious. We all have few special talents in life, but I am passionately curious about what animates life. The only difference between me and a madman is that I’m not crazy! I never give up the quest to know why.

        • Jack Kruse

          This is precisely how the atom fills its electron valence shells too…….inner most to outer most. It is evolutionary fractal design buried in Kleiber’s power law

        • You’re a “target” because you talk about some complicated shit!

          People can understand “diet & exercise,” so they want to believe all the answers sound something like “more steak & kettlebells.” Even the importance of excess artificial light exposure is a tough sell despite the fact that there are a ton of data supporting it…

          “Conspiracy ‘theories’ are first rejected as either treason or madness, then ridiculed, then accepted as common knowledge.”

          a more applicable quote might include something to suggest these ‘theories’ are rejected because they aren’t understood and only accepted when they are. [end rant]

  • I ordered the 2nd most popular blueblockers onAmazon; the uvex are hideous plus do not cover enough of the eye area for a night shift worker.

    I am so excited and hope these work. totally blacking out my roomwas an amazing improvement for sleep so perhaps stopping the light assault before bed entirely helps even more.

  • Blue Light Stimulates Cognitive Brain Activity in Visually Blind Individuals (Vandewalle et al., 2013)

  • Home lighting before usual bedtime impacts circadian timing

    Uvex Skypers, tested again clinically: participants started wearing them 4 hours prior to bedtime = significantly reduced time to fall asleep.

  • Kasha

    Wow, we have a lot in common. We could be friends. Good post. 🙂

  • TechnoTriticale

    I took notice lately of a retail store promoting a Philips blue night light in support of the “Light It Up Blue” campaign for autism. Obviously, a great many somebodies did no basic due diligence whatsoever, or if they did, they decided to not err on the side of caution in their spectral choice.

    Even wiki has been saying for some time (cites won’t work here): “Melatonin might improve sleep in people with autism spectrum disorders (ASD).[104] Research has shown that children with autism have abnormal melatonin pathways and below average physiological levels of melatonin.[105][106]”

    Words like clueless, careless, irresponsible and insane came to mind.

  • Jana Griff

    Hey Bill, nice and detailed post! Love your writing style. I have a question. Have you used the more high end glasses such as the ones presented on this page: ?

    • Hi Jana, Thanks!

      I’ve used some other higher end glasses, but the better they are at blocking blue light, the more red/amber the lenses are. For example, Gunnars are good if you’re on the computer a lot, but they won’t block blue light as well as Uvex Skypers.