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.


©2019 by the Biohacking Division at UCLA