Nightly exposure to blue light is an insidious public health crisis that is currently not being treated as one [1]. Humans' circadian rhythms have a period slightly longer than 24 hours. Hence, they needs daily entrainment to 24 hours with cues from the environment. That means that we're meant to experience sunlight in the morning, and darkness at night. When a person exposes themselves to blue light at night, melatonin is suppressed [2]. Think of melatonin as the biochemical expression of darkness, and the absence of melatonin as the biochemical state of daytime. If you expose yourself to blue light at night and melatonin is never secreted, your body will receive cues that it's 11:00 AM—even when the actual time might be 11:00 PM. This disrupts your circadian rhythm, which leads to increased weight gain, immune system dysfunction, and an increased risk of cancer [3]. Recent evidence strongly suggests circadian and sleep disorders as causal agents in mood disorders [4]. Single nucleotide polymorphisms (SNPs) in the BMAL1, Period3, and Timeless genes have all been linked to major depressive disorder and bipolar disorder. In essence, exposing yourself to blue light at night is like pulling out the crown on your body's watch and haphazardly winding it a dozen times in a random direction.

Blue-light exposure is a classic example of a mismatch between the society we live in and the EEA in which we evolved. In the last 200,000 years, there has never been a time where exposure to blue light did not also mean that the sun was out. Thus, we evolved to interpret blue light as being a cue of daytime. The goal of this biohack is to replicate the conditions of our EEA for which our genes are adapted to, at least with regard to the presence and timing of blue light.


Blue light suppresses melatonin

The dotted lines represent the "treatment" condition. Notice how red light exposure doesn't significantly change melatonin levels, but blue light exposure does. The goal then, is to maximize endogenous melatonin secretion, and to prevent blue-light induced melatonin inhibition. We can achieve this in two ways.

Reaching Out to the Sun

Sunlight and protein in the morning enhance melatonin secretion at night [5]

From an evolutionary perspective, this makes sense. Humans have always been exposed to sunlight in the mornings. We can dive into the protein bit in the Diet biohack, but the takeaway here is that sunlight is crucial environmental cue that orients the body's clock. Try to expose yourself to as much sunlight as possible during the daytime. This can be difficult in our modern society, which is almost designed to maximize the time spent indoors. Luckily, there is a ton of walking around between classes at UCLA, so this step shouldn't be too much of a problem.


Blue-blocking glasses increase sleep quality and mood [6]

How? By inhibiting the suppressive effects of blue light on melatonin secretion [7]. In other words, blocking blue light at night allows your brain to produce the optimal physiological amount of melatonin at exactly the right time—provided you put your glasses on as soon as it becomes dark outside. By only blocking blue light, you can continue to use electronic devices at night without incurring any disruptions to your circadian rhythm. This means better sleep, a better ability to meet the demands of of being a UCLA student, and greater overall health throughout your life.

Here are some potential options, from cheapest to most expensive:



[1] Hatori M, Gronfier C, Van Gelder RN, Bernstein PS, Carreras J, Panda S, Marks F, Sliney D, Hunt CE, Hirota T et al. . 2017. Global rise of potential health hazards caused by blue light-induced circadian disruption in modern aging societies. NPJ Aging Mech Dis 3:9.

[2] Wright HR, Lack LC, Kennaway DJ. 2004. Differential effects of light wavelength in phase advancing the melatonin rhythm. J Pineal Res 36(2):140-4.

[3] Zelinski EL, Deibel SH, McDonald RJ. 2014. The trouble with circadian clock dysfunction: multiple deleterious effects on the brain and body. Neurosci Biobehav Rev 40:80-101.

[4] Zaki NFW, Spence DW, BaHammam AS, Pandi-Perumal SR, Cardinali DP, Brown GM. 2018. Chronobiological theories of mood disorder. Eur Arch Psychiatry Clin Neurosci 268(2):107-118.

[5] Wada K, Yata S, Akimitsu O, Krejci M, Noji T, Nakade M, Takeuchi H, Harada T. 2013. A tryptophan-rich breakfast and exposure to light with low color temperature at night improve sleep and salivary melatonin level in Japanese students. J Circadian Rhythms 11:4.

[6] Burkhart K, Phelps JR. 2009. Amber lenses to block blue light and improve sleep: a randomized trial. Chronobiol Int 26(8):1602-12.

[7] Sasseville A, Paquet N, Sevigny J, Hebert M. 2006. Blue blocker glasses impede the capacity of bright light to suppress melatonin production. J Pineal Res 41(1):73-8.