The effects of blue light on the circadian rhythm

In modern times, light sources are a necessity for everyday society. The use of high brightness light-emitting diodes (LEDs) has grown to be the quintessential light source for not only industrial uses, but for personal devices such as computers, smartphones, tablets, and TVs. The most common type of LED is the white-light LED which uses a combination of emissions from a blue LED with a yellow phosphor that appears white to the eye. White-light LEDs also degrade over time, shifting the balance of the two emissions such that the blue emission increases with time [1].

In mammals, there are three types of photoreceptors: cones, rods, and intrinsically photosensitive retinal ganglion cells (ipRGCs). While cones and rods are responsible for image-forming vision, the ipRGCs are responsible for non-visual stimulus [1],[2]. ipRGCs contain melanopsin which is transmitted to the suprachiasmatic nucleus (SCN) in the hypothalamus. The SCN acts as a master clock that secretes a hormone called melatonin which signals night to the human body. The secretion of melatonin is cyclic, where it is high at night and low in the daytime. Studies have shown that the shorter wavelengths emitted from blue light (ranging 460 – 480 nm) are linked to melatonin suppression. Studies have additionally shown that blue light can increase alertness and stimulate cognitive functions [2].

There have been several studies [3],[4],[5] showing that blocking blue light emissions have helped those with insomnia symptoms. In the study by Shechter et al. (2018), blocking blue light for two hours before bedtime for one week resulted in a significant improvement in sleep.

Melatonin suppression is a highly efficient response to light wavelengths of 460-480 nm, representing blue light. Wavelengths of 555 nm or greater, representing the warmer yellow-reddish hues, are significantly weaker in suppressing melatonin compared to blue light [6],[7]. While darkness is ideal for melatonin expression, it can be concluded that in instances where illumination is required, the reddish hues are more desirable to avoid melatonin suppression.

[1] Tosini, G., Ferguson, I., & Tsubota, K. (2016). Effects of blue light on the circadian system and eye physiology. Molecular vision, 22, 61.

[2] Tähkämö, L., Partonen, T., & Pesonen, A. K. (2019). Systematic review of light exposure impact on human circadian rhythm. Chronobiology international, 36(2), 151-170.

[3] Shechter, A., Kim, E. W., St-Onge, M. P., & Westwood, A. J. (2018). Blocking nocturnal blue light for insomnia: A randomized controlled trial. Journal of psychiatric research, 96, 196-202.

[4] Janků, K., Šmotek, M., Fárková, E., & Kopřivová, J. (2019). Block the light and sleep well: Evening blue light filtration as a part of cognitive behavioral therapy for insomnia. Chronobiology international, 1-12.

[5] Zimmerman, M. E., Kim, M. B., Hale, C., Westwood, A. J., Brickman, A. M., & Shechter, A. (2019). Neuropsychological function response to nocturnal blue light blockage in individuals with symptoms of insomnia: a pilot randomized controlled study. Journal of the International Neuropsychological Society, 25(7), 668-677.

[6] Bonmati-Carrion, M. A., Arguelles-Prieto, R., Martinez-Madrid, M. J., Reiter, R., Hardeland, R., Rol, M. A., & Madrid, J. A. (2014). Protecting the melatonin rhythm through circadian healthy light exposure. International journal of molecular sciences, 15(12), 23448-23500.

[7] Brainard, G. C., Hanifin, J. P., Greeson, J. M., Byrne, B., Glickman, G., Gerner, E., & Rollag, M. D. (2001). Action spectrum for melatonin regulation in humans: evidence for a novel circadian photoreceptor. Journal of Neuroscience, 21(16), 6405-6412.


The effects of sleep on immune health

Today as we know there is a great amount of discussion on keeping healthy. There have been several studies showing the effects of sleep or lack thereof. The latter has shown increasing vulnerabilities to viruses. [1][2]

More than ever with COVID-19, no one wants to get sick. Getting the coronavirus today means a lot worse than just having the sniffles and people telling you to feel better. Even if you are a relatively healthy individual you do not want to fall into the risk group. There can be a lot of social and financial implications.

A good way that it has been put is, “Even though we are all in the same storm, we are all on different boats.”

 There may be a further financial burden on individuals. Not everyone is salaried and self-isolation can make a huge difference in hitting sales targets or other type of work productivity. Not only that but these days an employer might require you to do intrusive testing. These tests are something that quite a bit of us do not want to subject ourselves to.

With that being said, the new studies show COVID-19 disturbances and not the virus itself can compromise the quality of sleep. And this of course the immune system itself. [3]

To avoid these circumstances, it is important to know your body better and really understand when you are being worn down and how to recover from it. The science backs up that sleep is a vital part of having a strong immune system and that barrier against these viruses.

For this 2015 study conducted they wanted to confirm by measuring the actual sleep duration with a wrist actigraphy vs previous studies that used subjective recall of the patients. [1]

A total of 164 healthy men and women (age range, 18 to 55 y) volunteered for this study. Wrist actigraphy and sleep diaries assessed sleep duration and sleep continuity over 7 consecutive days. Participants were then quarantined and administered nasal drops containing the rhinovirus and monitored over 5 days for the development of a clinical cold (defined by infection in the presence of objective signs of illness). Logistic regression analysis revealed that actigraphy-assessed shorter sleep duration was associated with an increased likelihood of development of a clinical cold. [1]

A longer 14-day study showed the same results [2]

Additionally, increases in pro-inflammatory cytokines following sleep loss could promote immune system dysfunction. [4]

The conclusion was that shorter sleep duration was associated with increased susceptibility to the common cold viruses.

[1]Prather, A. A., Janicki-Deverts, D., Hall, M. H., & Cohen, S. (2015). Behaviorally Assessed Sleep and Susceptibility to the Common Cold. Sleep, 38(9), 1353–1359.

[2] Cohen, S., Doyle, W. J., Alper, C. M., Janicki-Deverts, D., & Turner, R. B. (2009). Sleep habits and susceptibility to the common cold. Archives of internal medicine, 169(1), 62–67.

[3] Silva, E., Ono, B., & Souza, J. C. (2020). Sleep and immunity in times of COVID-19. Revista da Associacao Medica Brasileira (1992), 66Suppl 2(Suppl 2), 143–147.

[4] Fullagar, H. H., Skorski, S., Duffield, R., Hammes, D., Coutts, A. J., & Meyer, T. (2015). Sleep and athletic performance: the effects of sleep loss on exercise performance, and physiological and cognitive responses to exercise. Sports medicine (Auckland, N.Z.), 45(2), 161–186.

Peak Performance

Importance of Recovery for Top Performers

Being a top performer requires top-level recovery. This starts with sleep recovery! Of course, to be a peak performer you need to have all aspects of your recovery game at their highest level. This includes proper nutrition, massage therapy, stretching, meditation, and most important, being consistent with all of this. When you have all of that in your bag, adding high-quality sleep is when you have the potential to reach another level.

Roger Federer famously snoozes for an average of 12 hours a night, while Lebron James, Usain Bolt, Venus Williams, Maria Sharapova, and Steve Nash get up to 10 hours a night. Federer has said, “If I don’t sleep 11 to 12 hours per day, it’s not right. If I do not have that amount of sleep, I hurt myself”

The amount of research that has gone into high-level peak performance sports and sleep is endless:

Sleep is essential for the cellular, organic, and systemic functions of an organism, with its absence being potentially harmful to health and changing feeding behavior, glucose regulation, blood pressure, cognitive processes, and some hormonal axes. Among the hormonal changes, there is an increase in cortisol (humans) and corticosterone (rats) secretion, and a reduction in testosterone and Insulin-like Growth Factor 1, favoring the establishment of a highly proteolytic environment. [1] This means that there is going to be decreasing in protein pathways resulting in fatigue, and muscle atrophy which can result in poorer performance, and even worse, the dreaded sports injury.

Another study looked at college athletes and sleep: Deficient sleep, regardless of cause, decreases neurologic function and is manifested by decreased performance. Sleep extension or napping, particularly in the context of sleep deprivation, improves neurologic function and as a result, improves performance. [2]

Here is another study looking at sleep and reaction time:

In a 36-hour sleep deprivation deleteriously affected 5-choice continuous performance test, the performance of both humans and mice. Importantly, sleep deprivation primarily reduced target responding in both species, with a smaller effect on reducing non-target responding, indicating that sleep deprivation is primarily deleterious to vigilance and not overall responding. [3]

For You:

Burnout is something the everyday person can experience. The result is poor performance in your everyday tasks. Whether this is poorer performance in recreational sports, injuries sustained by these sports, or even mistakes that can affect your bottom line or even the safety of people you are out there to help. There are studies looking at the negative effects of sleep in the medical community. [4]

The important thing to note is that we all can maximize our performance in whatever we are doing if we use all the tools available to us. The biggest tool that we sometimes forget is the importance of proper recovery and that is not possible without high-quality sleep.

[1] Dattilo, M., Antunes, H. K., Medeiros, A., Mônico Neto, M., Souza, H. S., Tufik, S., & de Mello, M. T. (2011). Sleep and muscle recovery: endocrinological and molecular basis for a new and promising hypothesis. Medical hypotheses, 77(2), 220–222.

[2] Bolin D. J. (2019). Sleep Deprivation and Its Contribution to Mood and Performance Deterioration in College Athletes. Current sports medicine reports, 18(8), 305–310.

[3] van Enkhuizen, J., Acheson, D., Risbrough, V., Drummond, S., Geyer, M. A., & Young, J. W. (2014). Sleep deprivation impairs performance in the 5-choice continuous performance test: similarities between humans and mice. Behavioural brain research, 261, 40–48.

[4] Olson, E. J., Drage, L. A., & Auger, R. R. (2009). Sleep deprivation, physician performance, and patient safety. Chest, 136(5), 1389–1396.