The internal 24-hour-clock, within the brain (Circadian Rhythm) makes humans feel tired or alert at regular times of night and day, respectively. Of a 9-year old, Circadian Rhythm would have him sleep by around 9 PM. As he reaches 16 years of age, Circadian Rhythm is many hours away. He’s no interest in sleeping at 9 PM.
By the time the Circadian Rhythm and Melatonin (hormone of darkness/vampire hormone that releases instructions) force the parents to sleep, teenagers are still wide awake. This is frustrating for all parties involved in the back-end of sleep.
No matter parents want children to obey their instructions the teenagers won’t be miraculously coaxed into a change. For parents, the teenager’s sleep patterns reflect a conscious choice and not a biological edict, even when they’re non-volitional, non-negotiable and strongly biological. Thanks to socio-evolutionary reasons.
As the independent adolescent wings unfold and the first solo-flights from the parental nest occur (not daytime, but rather a nighttime, courtesy, forward-shifted Circadian Rhythm) the changed rhythm returns. The teenagers are ageing into young and middle adulthood.
Human beings are solar-powered in the sense when the light fades so too does the solar-brake pedal, blocking Melatonin. As Melatonin rises, another phase of darkness is signaled and another sleep-event is called to the starting line. Most of our activities cease after sunset, as they’re predicated on vision, supported by daylight. The setting sun takes with it this full stream of daylight from our eyes, sensed by the 24-hour clock within the brain.
The loss of daylight informs it that night-time is now in session, instigating pineal gland to unleash vast quantities of Melatonin, heralding that ‘sleeping times are here again’. Approximately scheduled tiredness, followed by sleep normally occurs several hours after dusk across the human collective.
Beyond longer commute times and sleep-procrastination caused by late evening TV watching and digital entertainment, both are important in their top-and-tail snipping of sleep-time of children and adults. With Thomas Edison building the first power-generating station, Homo sapiens unbuckled themselves from the 24-hour cycle of light and dark. Humans and not the rotating earth decide now when it’s night and when it’s the day. Predominantly a visual creature, for humans it was far-exceeding olfactory, auditory & lingual functions. They grew into night-owls, owls by choice.
The advent of fire had a modest effect, thanks to the limited halo of light that offered an extension of post-dusk activities….singing, storytelling of hunter-gatherers. Gas-and-oil-burning lamps and candles soon spilt out of homes onto streets, bathing cities and towns with illumination.
The nocturnal-rhythms of societies and individuals became quickly subject to light-a- night, so began our advancing march toward later bedtimes. The incandescent light-bulbs guaranteed humans no longer spend much of the night in darkness, taking toll of our natural timing and quality of sleep. Electric light put an end to our natural order of things.
Artificial evening light even that of modest strength (lux)fools us into believing the sun hasn’t yet set. The Melatonin that otherwisewould have been released with the dusk timings remains unleashed. The forwardprogress of biological-time that is normally signalled by the evening surge ishalted. Sleep is delayed from taking off the evening-runway, which wouldnaturally occur anywhere between 8-10 PM. We’re tricked into believing night isstill day and does so using physiological lie.
As the evening electric light winds back our internal 24-hour clock by 2-3 hours, our bedside clock may be registering 11 PM, but the omnipresence of artificial light has paused the internal tick-tocking of time by hindering the release of Melatonin.
Artificial evening and nighttime, therefore, masquerade as the inability to begin sleeping soon after getting into bed. As you finally turn out the bedside lamp hoping for sleep to come it’ll be sometime before the rise of Melatonin is able to submerge your brain and body in peak concentrations instructed by the darkness that only now has begun.
The visible light spectrum—that which our eyes cansee—-runs the gamut from the short wavelength of approximately 380 nanometersthat we perceive as cooler violets and blues, to the longer wavelengths ofaround 700 nanometers that we sense as warmer yellow and reds. Sunlight is acacophony of all these colours and wavelengths and those in between.
The invention of blue light-emitting diodes or blue-LEDs offers considerable advantages over incandescent lamps in low-energy consumption and longer life-spans.
The light receptors in the eye that communicate daytime are most sensitive to short-wavelength light within the blue spectrum. As we stare at LED powered laptops screens, smartphones, iPads and tablets each night, sometimes for many hours, often with these devices just feet or even inches away, melatonin release affects the ability to time the onset of sleep, when compared with reading a printed book.
LED devices are a wonderful piece of technology thatenriches our lives and education, but as they enrich eyes and brains withpowerful blue light they impact our natural sleep rhythms, the quality of oursleep, and how alert we feel during the day. Remember, when sleep is abundant,minds flourish. When it’s deficient they don’t.
Human beings, as is believed, emerged from marine life. The ocean acts like a light-filter, stripping away most of the longer, yellow and red wavelength light. What remains is the shorter, blue-wavelength light which’s why when submerged under its surface, to us ocean appears blue.
Much of the marine life, therefore, evolved within the blue visible light-spectrum, including the evolution of aquatic eyesight. Our biased sensitivity to cool blue light is a vestigial carryover from our marine forebears.
Unfortunately, this evolutionary twist of fate has now come back to haunt us in a new era of blue LED-light, confusing our melatonin rhythm and thus our sleep-wake rhythm. Hopefully, we’re able to engineer LED-bulbs and phones and IPads with filters that can vary the wavelengths of light that they emit ranging from warm yellow colours less harmful to melatonin to strong blue light that powerfully suppresses it.