This week’s column actually begins many, many years ago — back in the era before technology, back even before civilization. During this time, humans lived off the land, eating what they could hunt or gather. They lived in makeshift shelters, and much of their lives revolved around simply staying alive.
Survival breeds some interesting features within humans. Humans accumulate fat to nourish to body when food isn’t available. A fight-or-flight instinct kicks in when a stressful situation is encountered. And interestingly, when the sun goes down, humans go to sleep.
This human feature may come as a surprise to many readers. Today’s society almost completely discounts the division between day and night. Business and commerce maintain extended hours well into the nighttime hours. Twenty-four hour stores are becoming standard operating procedure. Folks who adhere to the sun’s natural cycle are often chided for being old-fashioned or out-of-date.
No matter how you look at it, observing the difference between night and day just isn’t cool.
While current-day humans have divorced themselves from the concepts of day and night, this adaptation is relatively new. Society didn’t start ignoring the darkness until the beginning of the last century.
Thomas Edison can be rightfully blamed for starting the change. The electric light bulb is the invention that allowed humans to conquer the night. Before the electric light bulb, humans were fully conditioned to do one thing when the sun went down — sleep. And after many millennia of conditioning, the human body has sleep down to a science.
The science kind of goes like this — an area of a human’s brain called the hypothalamus is, among its other functions, responsible for initiating the signals that make humans feel sleepy. A key factor in the process is the exposure to light or to darkness. Darkness initiates several biological functions that lead to sleep. Likewise, exposure to bright light starts the biological engines make humans awake and alert.
The hormone melatonin appears to be associated with the human sleep cycle. When darkness occurs, the brain begins to produce melatonin. Melatonin levels stay high through the night. When exposed to bright light, the melatonin levels fall and, during daylight hours, melatonin levels are barely detectable. Melatonin production typically occurs on a 24-hour cycle, staying in sync with the natural daylight cycle.
Artificial lighting messes things up pretty badly. Exposure to a well-lit environment after daylight hours causes the body to go out of sync, impacting sleep, blood pressure, diet and leads to a whole host of other bad things. The light directly inhibits the release of melatonin. Even when the body clock says its time for sleep, the body won’t begin the process. Even worse, the brain won’t produce the melatonin that influences the process until the person is in a dimly lit environment.
Sitting in a dark room with a phone or tablet less than an arm’s length from your face doesn’t count — it actually makes things worse. LED devices such as smartphones, tablets and energy efficient light bulbs tend to produce a bluish-tinted light. According to a Harvard study, the blue light creates a more significant impact on melatonin production, suppressing melatonin for almost twice as long. The number of blue light sources has greatly increased in the last few years, and the experts are concerned that these light sources significantly impact people’s sleep patterns.
And that brings us to right now, and the struggle we all have with managing our 24×7 connections. Some recommendations indicate that phone and tablet usage should stop two to three hours before sleep. Honestly, I’m not sure how that is possible, but certainly we can manage 30 minutes to an hour. Other recommendations include the use of red-tinted lighting during evening hours and for nightlights. That sounds like a perfect excuse to purchase smart lighting!
Hopefully, many millennia from now, the human sleep cycle will adapt to the reality of always-on artificial lighting. Our descendants will be in a much better position for space travel and colonizing planets with different daily cycles.
Yes, it will be a different world — a world where the screen light from a table won’t impact any biological rhythms.
(Of course, by that time, the human-computer interface will likely be surgically implanted. But that’s a different article…)