Over the past couple of centuries, artificial light has gradually become a ubiquitous part of our environment. The modern man is constantly exposed to artificial light emitted by smartphones, lamps, and computers. It’s easy to forget that these light-emitting devices are extremely novel additions to our environment. Throughout the vast majority of our evolutionary history, nobody owned a computer or a smartphone or was exposed to artificial light emitted by lamps, cars, or street lights. This is very important to acknowledge, in part because it implies that we are not genetically adapted to live in an environment that is saturated with artificial lighting.
What are the consequences of living in a world where there is no darkness?
Our preindustrial ancestors didn’t have the option of turning on a lamp when the sun went down in order to keep darkness at bay. Nor did they have the possibility of chatting with friends on Facebook messenger until late at night or do some last minute work on a computer right before they hit the sack. They had to make do with natural light emitted by the sun. They also had the option of lighting a fire or bringing out some candle lights after the sun went down; however, they obviously didn’t have access to the myriad of devices that we – contemporary humans – use to illuminate our surroundings.
There’s little doubt in my mind that this is one of the main reasons why many sleep-related disorders have increased in prevalence lately. Not only are conditions such as insomnia fairly common these days, but many, if not most, contemporary people rarely, if ever, get a truly good night’s sleep. The modern man is groggy and tired in the morning and downs a lot of caffeine and sugar throughout the day in order to keep his energy levels up. It could be argued that he’s never completely awake, nor is he ever completely asleep. He does sleep; however, the quality of his sleep is not optimal, in large part because his environment is filled with sleep-disrupting agents such as smartphones, computers, and highly processed, sugary foods.
Lamps, computers, and smartphones have the potential to severely disrupt the quality of one’s sleep, as well as other aspects of one’s life. This statement is not just based on my own experience, but also on countless scientific studies. Exposure to artificial bright light during the nighttime is particularly damaging, in that it suppresses melatonin secretion, increases sleep onset latency, and increases alertness (1, 2, 3). This circadian misalignment may in turn have negative effects on psychological, cardiovascular and metabolic functions and increase one’s risk of developing several types of chronic diseases, including breast cancer (1, 2, 3).
Virtually every part of our physiology is affected by the quality and duration of our sleep. If you don’t sleep well, you may get cravings for unhealthy food, feel mentally drained, and have trouble keeping your energy levels up throughout the day.
Some light-emitting devices are more destructive than others
Artificial light, regardless of its origin, can impair the quality of our sleep. With that said, some forms of artificial light are particularly bad. Computers, smartphones, e-readers, and similar devices have the potential to turn what would otherwise have been a good night’s sleep into a nightmare. Not only do these devices emit light that is particularly good at suppressing the production of hormones (e.g., melatonin) that bring us to sleep (4, 5, 6), but they also light up our brains, in the sense that they are a source of endless information and stimuli. Basically, they keep our brains engaged and signal that it’s time to work, not sleep.
It makes completely sense that smartphones and computers affect us this way, seeing as our brains are evolutionarily programmed to gear up when they are stimulated by stressors or an influx of information.
Why aren’t the sleep-disrupting properties of artificial light more widely known about?
When I was younger, I remember being largely unconcerned about the effects that regular exposure to artificial light had on my body. I often used my smartphone late at night as I was lying in bed; I didn’t turn off the lamps in my room until right before I headed to bed; and I hadn’t incorporated any sleep optimization strategies into my life.
I know a lot of people operate in a similar manner as I did back then.
My impression is that a lot of people don’t know that artificial lighting has the potential to severely impair the quality of their sleep. Like my younger self, they lie in bed at night surfing or chatting with friends on their smartphone and don’t think much about how all the artificial light they are exposed to on a daily basis affect their production of sleep hormones such as melatonin.
It’s not really surprising that these beliefs and practices are so common, seeing as health authorities and the mainstream media pay little attention to how all of the artificial light that we are bombarded with on a daily basis affects us.
Things would probably have been very different if evolutionary health theories were more widely incorporated into our society. If everyone who conveyed health information to the public acknowledged that natural selection has never gotten around to adapting the human body to a world where there is no darkness, the dark sides of artificial lighting would undoubtedly have been more widely known about.
Our brains, internal biological clocks, and hormone systems were designed to work well in an environment that differs markedly from the environment that we currently find ourselves in. Sleep optimization is a key component of a healthy lifestyle. One of the most important steps we can take to sleep more and better is to limit our use of light-emitting devices, particularly late at night.