Circadian Rhythmicity - Sunlight, Bluelight, Backlight: How Street Lamps, iPads & Co Mess W/ Our Internal Clock. Plus: Tweaks, Tools & Apps to Prevent Negative Side-Effects

Image 1 (uci.edu): There are billions of clocks in our world, but the most important one of all, our biological clock has gained scientific attention only over the past couple of years - a momentous mistake, as scientists are starting to realize.

This is the first installment of the long promised yet often postponed SuppVersity series on Circadian Rhythmicity and how it impacts your physiology and psychology. Despite the fact that I eventually decided to spare you all the funky acronyms, clock genes and hardly legible names of at best incompletely understood feedback mechanism and complex switches I cannot forbear discussing a couple of fundamental principles to set the scene and ensure you understand what I am talking about, when I say "blue light" or "melantopic part of the spectrum". Don't be scared, I am trying to make it as easy as possible and if you still don't understand a word, I would hope that you do at least enjoy my sense of humor ;-)

Before we get lost in all the complicated details, yet again, let's start out right away by shedding some light (pun intended) at the most obvious, easiest to understand and to a great degree tweakable control parameter of our circadian rhythm: Light!

Sunlight! What do you know about it? And how does it control your circadian rhythm?

Image 2: Sir Isaac Newton used a prism to make the frequency spectrum (for us, the frequency determines the color of the light) visible

Let's start with a question that sounds so stupidly simple that you will probably rarely ever hear it voiced publicly: What exactly is sunlight? There are about as many answers to this question as there are photons, which are emitted from the photosphere of our sun in every second. Fortunately, we do - as it is common in science - not have to provide the one and only correct answer to this question but can rather pick the contextually appropriate one from a set, which does, among other answers, also comprise the Bethe-Weizsäcker cycle, the wave- and particle model of light and many other intricate theories. For our current purposes, it will yet suffice to keep in mind that light is an entity which has two physiologically important qualities:

• intensity, which would be the number of the photons per time unit that's hitting a certain area of retina and 
• frequency, which denotes the energetic load each of this photons is carrying (frequency = speed of light / wavelength)

Since the number of photons we are exposed to at every given moment we are not surrounded by total darkness is incomprehensibly large, we do not notice that each of them has a distinct frequency. To us, the light of the sun appears to be yellowish white and that despite the fact that Sir Isaac Newton already knew (and artfully demonstrated, as you can see in image 2) that our "white light" is in fact blue, green, yellow, turquoise, red, violet, ...

Figure 1: Each light source has its characteristic spectrum, i.e. it emits light with different frequencies (in case you forgot, you get the frequency of light by dividing the speed of light by the wavelength), or physically speaking photons with a characteristic energy distribution - relative to the total amount of photons sunlight, for example, contains much more highly energetic "blueish" photons, while the light of one of the classic Edison-esque light bulps contains a higher amount of low energy (high wavelength = low frequency) "reddish" photons.

Now the actual "spectrum", as scientists call the set of distinct frequencies in a certain signal, of our sunlight, is - contrary to what figure 1 may suggest - not continuous, but discrete. Moreover, for any given light source (our sun included) the occurrence or non-occurence of certain frequencies is highly dependent on the particles by which the light is emitted. Astronomers use this fact to their advantage and determine the material composition of stars by analyzing their characteristic light spectrum, which, in the case of our sun, covers a visible and non-visible part (in this case "visible" designates visible to our eyes). The reason I am emphasizing this here, is simple: Just as or sun has its characteristic spectrum, the light bulb in the lamb on your desk, the backlight of your computer screen, the tube of your old television screen, the lamps on the street, and so on and so forth... they all have their individual spectral foot- or maybe I should rather say frequency-print.

What does blue light say? It says: "Get up, it's a new day!"

Image 3: Melatonin (blue) is produced in the pineal gland (purple) in the absence of light stimuli (Soc for End. 2011)

This is important, because sunlight and a couple of million year later the light of fire, evolution has had little time to catch up with all those "strange" light sources it is facing today. And despite the fact that the ingenious invention, we know as "eyes", has undergone numerous evolutionary revisions, ever since nature invented the prototype (probably) during the so-called Cambrian Explosion a couple of million years ago, the specific composition of the light it was made to detect never changed, until homo (sometimes not exactly) sapiens entered the scene and had the ingenious idea to use artificial light source to finally put an end to the annoying rhythmicity of light and dark  and boring spectral homogeneity of the light, we are now no longer exposed to on daily basis only, but - more often than it would be conducive for our health - on a nightly basis, as well.

Only over the course of the past two to three decades, however, are we finally beginning to understand that the handy 24/7 availability of "light" at any desired intensity, along with the oftentimes unnoticeable otherness of this light with respect to its spectral composition (see figure 1) may constitute one of the most underrated health risks we are facing in our 24/7 convenience society: Light pollution.

What does artificial light say: "Stay up it's not yet night... but wait, it's not really day, either!?"

The sentence "most polluting are the lamps with a strong blue emission, like Metal Halide and white LEDs" from one of the most recent reviews of the literature on "light pollution" does already tell you something about where we are heading, here. With the impeding disappearance Thomas Edison's good old light bulbs, the 'fire from the ancestral cave', as I would like to phrase it for all paleo lovers out there, is about to be extinguished ... isn't it interesting, by the way, that the discontinuation of the production of classic light bulbs is vindicated by environmental concerns ... but before I am losing sight of the topic at hand, let's rather take a look on how much worse those "modern" lighting systems actually are and what alternatives we have, if we don't want to return into our fire-lit or pitch dark (man-)caves certain people nobody would even know if it were not for the 100% non-paleolithic 24/7 "enlightening" invention of the Internet as yet another one cave... ah, pardon "one size", of course, fits it all solutions the lights from our computer screens are transmitting right into our brains.

Figure 2: At least for city lights and the like, the energy efficient yellowish sodium vapor lamps could provide some relieve of the nightly "light stress" we are exposed to (data based on Falchi. 2011)

If we take a closer look at the data in figure 2 we will certainly have to concede that the fire in the cave which does by the way have the greatest resemblance to the good old 65W incandescent light bulb from figure 2 was still relatively benign as far as its ability to suppress our natural melatonin production is concerned - 26% and even 54% less suppressive than energy efficient metal halide and LED based light sources as they are used in the funky xenon lights of your shiny new Porsche, or the bright display of your iPad, to be precise. And still, according to Falchi et al. who published a paper with suggestions on how to reduce the overwhelming (nocturnal) exposition to bright and more-importantly "bluish" (in this context this refers to light sources which emit signifcant amounts of light from the higher frequencies / lower wavelengths of the visible spectrum, cf. figure 1, blue) light sources, there would be a better solution to illuminate our streets at night than large campfires or energy-inefficient incandescent light bubs: The yellowish low pressure sodium lamps, at least those of you who live in Germany may remember from their childhood, when they were still used to illuminate crosswalks along otherwise unlit roads, constitute the least "light polluting" an,d at least from physiological point of view, most "sustainable" nocturnal lighting solution (Falchi. 2011).

A call for action: Reduction, revision, regulation?

Figure 3: Superposition of the spectra of sunlight.classic light bulbs and the meltopic = melatonin suppressive frequency band (latter from Hallan. 2004). It is obvious that the relative contribution of melatonin suppressing high frequency (=low wavelength ~380-550nm) light is significantly lower for light bulbs than for sunlight. With an almost monochromatic light emission in at 589.0 and 589.6 nm low pressure sodium lamps (not shown in this figure) are yet unrivaled, among the low(er) meltopic light.

In their paper with the title "Limiting the impact of light pollution on human health, environment and stellar visibility" Falchi et al. also suggest that need for policy makers and scientists to collaborate to come up with prescriptions and technologies that would

• take account of existing nighttime lighting habits in order to minimize the impact on human activities
• allow easy identification of non-compliant light sources and
• allow easy measurement in the field, when needed

In addition, Falchi et al. formulate the following very concrete recommendations, which are (surprise!) even supported by the American Medical Association (cf. AMA. 2009):

1. establish a "protected range" within the 440-540nm range of the spectrum that corresponds to the maximum sensitivity of the scotopic vision and will thus have the greatest effect on the natural nocturnal melatonin production
2. limit direct light exposure of the eyes by no not allowing luminaries to send any light directly at and above the horizontal
3. avoid over lighting, shut off lights when the area is not in use and restrict growth of the total installed flux

I will leave it up to you in how far you feel these measures are (a) effective and (b) how realistic it is to assume that they will put into practice anytime in the near future.

In case you agree with my personal assessment, though, and believe that relying on governmental regulation usually produces more problems than it solves, you will be happy to hear that the use of the previously mentioned blindfolds, dark curtains and even the use of blue blocking glasses, as suggested by Dom Leste in response to my recent post on the "1lbs Fat Loss Bonus of 40 Minutes of Additional Sleep", can provide the much needed relief from the melatonin suppressing effect of constant "blue-light" exposure (Sasseville. 2006). 

Technologically advanced approaches to nutural circadian rythmicity

Image 3: F.Lux is probably the most popular program to adapt your screen brightness and hue to the time of the day, but there are alternatives and mobile solutions of which Lux, for example, looks pretty neat.

And just in case you did not get your daily dose of SuppVersity news before it's actually high time to shut off your computer and mobile devices, there are meanwhile a couple of programs that will adjust the screen brightness and hue according to the time of the day. Based on my cursory review of the available software solutions (note: the angle at which the sunlight enters the atmosphere is the reason that it changes its "color" in the course of the day), the F.Lux software by Stereopsis is apparently the most popular among a whole host of programs which are available for almost every operation system from A as in Android to Z as in ... well, Z as is "WindowZ" *rofl* (see caption of image 3 for links).

So do those programs work? Or do they at least make sense?

Despite the lack of peer-reviewed research on the general, let alone individual effectiveness of these programs, the results of numerous recent publications on the negative effects of non-adaptive screenlight and even regular (undimmed) household illumination, on the natural circadian rhythm would suggest that the use of respective software programs, or simple electronic dimmers could limit well-established detrimental short term effects such as the...

• 

  Figure 5: Emission band of the iPad (white screen), blue LEDs and the transmission band of orange-tinted glasses (Wood. 2012) + the melatonin suppressive frequency band (red, dashed line, my addition) - it should be obvious that the iPad hits a homerun with his brilliant display and you can bet that the "Retina Display" of the iPad2 emits even more natural light ;-)

  ... -8% and -23% reduction in melatonin production from the use of an iPad at 00:00 or 01:00 a clock, respectively, Britanny Wood and her colleagues from the Lighting Research Center at the Rensselaer Polytechnic Institute in New York observed in 11 healthy subjects with a mean age of 18.9 years
• ... postponement (~2h) and shortening (-90min!) of the nocturnal melatonin expression which occurred in 99% of 112 young healthy subjects who were, just like about everyone who would be sitting in his office in the afternoon and on the couch in front of the telly in the evening, exposed to regular electric room light (constant spectral composition and intensity <200 Lux) for 8h before they went bed (Gooley. 2011)
• ...50%-90% suppression of melatonin, 80% of the people suffer from, when they accidentally or deliberately try to switch from one to another sleeping rhythm by simply not switching the light out and staying up late (Gooley. 2011)
• ... significantly more pronounced suppression of melatonin production of computer, laptop, mobile devices and TVs with LED displays as compared to the old-fashioned CCFL backlit displays (Bues. 2012)
• [...]

...I guess it's about time I stop listing all those negative effects, after all, even the above list, which is by no means comprehensive and could easily extended by two dozens of additional citations from the last 3 years, only, could convey the impression that it would in fact be the best for us to return into our man- and woman-caves, shut the electricity off and lead the idyllic life of our paleolithic ancestors... and if you want to do that and find a place where this is possible, I won't put a spoke into your... ah, wait wheels are neolithic witches' brew, but I guess you get the notion anyway ;-)

Don't worry, you don't have to reside in paleolithic darkness - thanks to neolithic science!

For the rest of you, I have already outlined a couple of easily implementable strategies to avoid the negative aspects of artificial light exposure, where the light (artificial or not) is not a necessary or desirable part of your life (blindfolds, curtains, special light sources, computer software, orange blue-blocking glasses, keeping the lights low, dimmers, etc.; check out my previous blogpost "1lbs Fat Loss Bonus of 40 Minutes of Additional Sleep", as well).

Figure 5: You can take this sketch of mine as a sneak peak of what to expect in the future installments of the Circadian Rythmicity Series and the smiley as a clear-cut evidence that we are not doomed to live in darkness for the rest of our miserable neolithic existance (parts of background image from Froy. 2012)

Apropos desirable, not all neolithic technology is bad and I am honestly darn happy I am no paleolithic hunter, let alone gatherer! Used appropriately, even the funky over-sized LED screen I recently got at the office has its advantages. Compared to a regular LCD screen, for example, it will significantly improve my working memory/attention, when I am working overtime (cf. Cajochen. 2011). Since I don't intend to make use of this advantage today, however, you will have to wait another week for the next installment of this series to be written if you want to learn about behavioral, psychological and technological tweaks and gimmicks by the means of which you can use light(s) to your advantage to realign a compromised circadian rhythm, increase cognitive and physical performance, minimize the negative effects of after hours or shift work and much more.

I for my part am now enjoying the sunlight for maximal melatonin suppression, cognitive and physical performance and a powerful signal to my circadian clock that she is still accurate and would suggest you do the same - unless you want to leave me some feedback on this first installment of the Circadian Rhythmicity Series and where you want it to be heading, of course!

References:

• American Medical Association (AMA), House of Delegates. Resolution 516 e Advocating and Support for Light Pollution Control Efforts and Glare Reduction for Both Public Safety and Energy Savings. 2009. 
• Bues M, Pross A, Stefani O, Frey S, Anders D, Späti J, Wirz-Justice A, Mager R, Cajochen C. LED-backlit computer screens influence our biological clock and keep us more awake. Journal of the Society for Information Display. 2012; 20: 266–272.
• Bukalev AV, Vinogradova IA, Zabezhinskiĭ MA, Semenchenko AV, Anisimov VN. Light pollution increases morbidity and mortality rate from different causes in male rats. Adv Gerontol. 2012; 25(1):49-56.
• Cajochen C, Frey S, Anders D, Späti J, Bues M, Pross A, Mager R, Wirz-Justice A, Stefani O. Evening exposure to a light-emitting diodes (LED)-backlit computer screen affects circadian physiology and cognitive performance. J Appl Physiol. 2011 May;110(5):1432-8. Epub 2011 Mar 17.
• Falchi F, Cinzano P, Elvidge CD, Keith DM, Haim A. Limiting the impact of light pollution on human health, environment and stellar visibility. J Environ Manage. 2011 Oct;92(10):2714-22.  
• Froy O. Metabolism and circadian rhythms--implications for obesity. Endocr Rev. 2010 Feb;31(1):1-24. 
• Gooley JJ, Chamberlain K, Smith KA, Khalsa SB, Rajaratnam SM, Van Reen E, Zeitzer JM, Czeisler CA, Lockley SW. Exposure to room light before bedtime suppresses melatonin onset and shortens melatonin duration in humans. J Clin Endocrinol Metab. 2011 Mar;96(3):E463-72.
• Hollan J. Metabolism-influencing light: measurement by digital cameras, Poster at Cancer and Rhythm Oct 14-16, 2004, Graz, Austria. 
• Sasseville A, Paquet N, Sévigny J, Hébert M. Blue blocker glasses impede the capacity of bright light to suppress melatonin production. J Pineal Res. 2006 Aug;41(1):73-8.
• Soc for End. "Melatonin" in Glosarry. 2011 March < http://www.yourhormones.info/hormones/melatonin.aspx > visited 2012 Aug 05.
• UCI.edu. Illustration to article "The Clock Watcher". < http://www.uci.edu/features/2009/05/feature_circadian_090528.html > visited 2012 Aug 05.
• Wood B, Rea MS, Plitnick B, Figueiro MG. Light level and duration of exposure determine the impact of self-luminous tablets on melatonin suppression. Appl Ergon. 2012 Jul 29. 

"80-85% 1RM, 6-10 Reps"? Changes in Muscle Fiber-Type in Response to Classic, Super Slow and Light Training Confirm "Old School Training" Rules and Will Always Prevail!

Image 1: If you don't want to be strong and look good naked, you better not train like "old school" like Arnold, Franco Columbu (img), Dave Draper, Frank Zane & Co.

Although, I do assume that you just dropped everything, went home from work early, or simply did not leave the house at all to be able to listen to my appearance on Carl Lanore's Super Human Radio, yesterday, I know that sometimes more important things (whatever that may be) get into one's way and will thusly give you a second chance, today (click here to download the podcast)... well, so far for the humorous part of this post. Assuming that by now, you did listen to the podcast you should remember that I promised to have something about exercise and strength training in the news, today. And as Carl will probably assert, Super Humans usually stick to their promises, although - and I did mention that yesterday, as well - the number of significant studies, i.e. studies that do not involve frail elderly or morbidly obese people, is relatively scarce.

Bro, you know the revolutionary new "GHRWZAR-642421 training principle"?

Image 2: If you are looking for a collection of proven routines, instead of bunch of old hats with funky new names, the Blueprint would be a good choice.

Beside the fact that our interest in improving our health and the way we look by diet and nutrition is not getting all too much love in the major scientific publications, another factor, which in all fairness should not be forgotten is that we do actually know what works, don't we? Sleep, eat, train... with the "common wisdom" with respect to "what is the best diet" being in constant flux, I guess, we are simply expecting to see similarly paradigm changes in the realms of exercise physiology, but aside from the occasional letter salad people are trying to sell you as the latest and greatest new training technique, which then turns out to be the 1001 iteration of what the fathers of physical culture have been doing for ... I guess, centuries, would be correct... the basics, which are to pick up a heavy weight move it through time and space for about 6-10 reps and rack it, never change - for a good reason as the pretty detailed results of a freshly published (actually still ahead of print) study from Mark D. Schuenke and his colleagues just confirmed anew (Schuenke. 2012). 

Lifting heavy objects makes women ... dunno, but not bulky, to say the least ;-)

I guess, I better mention it right away in order to avoid that you get all to psyched out and are disappointed in the end: The study participants were 34 untrained young women (21.1 § 2.7 years). And just to make sure there are no misunderstandings, here - the downside for physical culturists is that these women were untrained not that they were women! The latter, is, as the scientists point out, actually an advantage, because "in pre-vious studies, it has been easy to find eager, untrained female subjects with excellent compliance to protocols", which by the way is another thing, Carl and I talked about in yesterday's installment of Super Human Radio ;-)

The reason that the subjects training status ("untrained") is somewhat of a downside, is yet that the early adaption which occur once you first pick up the weights, are fundamentally different from the painfully slow gains of an advanced trainee or elite athlete. In the end, the latter is yet also part of the reason that scientists don't recruit athletes for studies like this, after all the gains" (both strength- as well as muscle-wise) these subjects would have made over the course of the 6-week study period, in which the ladies in this study performed a total of 17 training sessions (two in the first week, three per week in the subsequent 5 weeks), would have been hardly "significant" - and in this case we are talking about both, statistical, as well as real-world significance.

Figure 1: Graphical illustration of the three experimental conditions / training regimen in the study.

Figure 1 should give you the general idea of the three different training regimen the women were randomly assigned to. With the first one being heavy + fast (TUT was in fact 1-2s for both concentric and eccentric part of the movement; verbal count was provided to make sure the tempo was correct) representing what has worked pretty well for generations of strength athletes, the second one being a variety of the Super Slow principle and the third one representing the "I don't want to build muscle"-approach to weight lifting that is unfortunately still very popular among women, we have the whole spectrum from tried and proven to tried and worthless in here ;-) I guess, it should be mentioned that the number of sets (3 sets, to failure) and the exercises, which were leg presses, squats and knee extensions (I suppose the latter is identical to "leg extensions", but I thought I rather stick to what Schuenke et al. wrote) were identical so that the effective parameters which influenced the study outcome were time-under-tension (TUT + reps) and intensity (% of 1RM) - or to make a long story short: Lift heavy and fast, give yourself a hard time by lifting slow or just pump away with lousy weights to "shape your body" (I hope you see the irony wrt to the last point).

Everyone who believes in "shaping your body with high reps and light weights" raise your hand!

I guess, for most of you it won't  come as a surprise, when I am telling you that there were no changes in total body mass in the course of this 6-week training intervention, but what I guess will be surprising is that the body composition of the women did not change either (cf. figure 2)!

Figure 2: Fat mass (in kg) and fat free mass (in kg) before and after 6 weeks with a total 17 leg training sessions (data adapted from Schuenke. 2012)

If you scrutinize the data in figure 2 you could make a point that there was a 0.1% increase here and a 0.025% decrease there, but I guess, even if you have no clue how those p-values, which indicate if the change in a measured parameter could be mere coincidence are calculated, it is quite obvious that none of these changes reached statistical, let alone real-world significance.

If we take a closer look at what happened "inside" the vastus lateralis muscle from which the scientists took muscle biopsies before and at the end of the study period, it does yet become obvious that our "conventional exercise wisdom" is in fact much more reliable than its nutritional counterpart.

Figure 3: Changes in relative fiber composition in vastus lateralis muscle in response to 6 weeks of leg training with different loading / TUT / rep schemes (data adapted from Schuenke. 2012)

As you would expect, the muscle fiber-types shifted according to the load and the TUT / reps that were used with a generally more pronounced increase in the still highly glycolytic type IIA and type IIAX fibers in the classic standard RT group and a shift towards a more oxidative type II fiber type (type IIC) in the super slow group. As those of you who have read the Intermittent Thoughts on Building Muscle will know, the former precipitates both strength and size gains, while the latter would be something a "strength-oriented endurance athlete", as maybe a rower, could be interested in. What all three training regimen have in common though, is the decrease in the exclusively glycolytic type IIX fibers, of which those of you who have followed the aforementioned series will know that they are quasi-nonexistent in elite bodybuilders.

Training light does work, but does not really do the job

What is also noteworthy, is that the light, yet fast training with high reps, induced what you may call a "transition status", with initial changes in the type IIX fibers (becoming type IIAX), but without the a complete switch from the "unflexible" glucose guzzling type IIX fibers to the cornerstones of strong and big muscles - the type IIA fibers. In view of the fact that the scientists did not quantify the strength gains and that the "higher growth propensity" of type IIA fibers is somewhat of an urban myth, the study outcome with the greatest real-world significance is unquestionable the increase in fiber size, which, as the data in figure 4 goes to show was maximal in all three major fiber types in response to the classic training protocol.

Figure 4: Changes in cross sectional area of the different fiber types (data adapted from Schuenke. 2012)

If that is not enough to convince at least the male part in the audience that there is good reason that the good old "6-10 reps in the 80-85% 1RM range" is still around, I guess they must be beyond help... and as far as the ladies are concerned: I know you don't "wanna get big", but let me tell you this - "strong is the better sexy", and as Carl Lenore would probably add "muscle is metabolic currency". So, if you want to stay mobile into your old days, do your joints and bones a favor by strengthening them in time. Moreover, with the mitochondrial powerhouses in full-gear, a few fixes to your diet should suffice to make those "problem areas" not magically, but gradually disappear.

Apropos diet, while the subjects did not have to log their calorie let alone macronutrient intake, I would bet that with a simple protein shake after their training and some general tweaks to their diets, those favorable changes in body composition, i.e. decreases in fat and increases in lean mass, which are at the heart of "looking good naked" would have come about... with the "I love my pasta and red-meat gives you cancer"-diet from the latest cosmopolitan, on the other hand, you better stick to baggy jeans and huge sweaters instead of bikinis and speedos, ladies and gentlemen ;-)