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  • Mia Ca

Let There Be (Less) Light (at Night)

Updated: Aug 8, 2019

Natural lighting is the essence of life.


It helps us keep and tell time, provide visual information, and see the world in color but a vast body of research reveals that its importance goes far beyond that. It also enhances cognitive performance and the quality of sleep while reducing daytime sleepiness and regulating behavior and mood.


Darkness is, however, vital to sleep.


Artificial light in our surroundings interferes with sleep by disrupting the internal clock and delaying the circadian phase: we doze off with more difficulty, and much later than our ancestors did, we have trouble staying asleep and wake up exhausted in the morning, only to fight excessive daytime sleepiness. This represents the sleep crises of the 21st century, a by-product of the technological revolution that in many other spheres works to our advantage.


Let’s take a peek at some illuminating facts that will help you boost your health and spare you counting sheep.

Circadian Clock


Circadian rhythm is a range of physical, physiological, and behavioral changes that follow the 24-hour day cycle. It affects the sleep-wake patterns and has a remarkable effect on the quality of slumber. It controls alertness, hormone levels, body temperature, appetite, and cell regeneration. The circadian disruption has been linked to depression, bipolar disorder, as well as obesity and sleep disturbances.

Both the biological system (genes and proteins) and external factors (environment, work schedule, social engagements, family life, meal times and eating habits), impact the circadian rhythm (internal clock) which, if synchronized to the 24-hour day, has profound effects on health and well-being.


Rise and Shine


Natural light has a strong influence on academic performance and productivity. Findings show that exposure to daylight plays a significant role in students’ mood, physical and mental health, behavior, and learning.


When it comes to offices, the results are identical: natural lighting affects the visual, circadian, and perceptual systems. It enhances circadian rhythm and contributes to visual comfort and ambience, stimulation, interpersonal relationships, job satisfaction, and problem-solving skills.


Studies corroborated that exposing Alzheimer’s patients to bright lighting during the day can improve their sleep in by promoting sleep consolidation and reducing sleep disturbances.


Besides being a powerful regulator of the circadian cycle, natural light elevates mood, reduces daytime sleepiness, and bolsters productivity in healthy individuals.

While daytime exposure to light increases alertness, sharpens focus and boosts cognitive performance, the same exposure at night, right before bedtime or during slumber, disrupts sleep and increases daytime fatigue the following day.



The Dark Side of Light


The amount of light that we have been exposed to since the invention of the lightbulb in the late 19th century had a substantial influence on our sleep quality and made a fundamental change in our sleeping patterns.


Dr. Charles Czeisler, Chief of BWH’s Division of Sleep and Circadian Disorders, cites statistics, “In the past 50 years, there has been a decline in average sleep duration and quality.”


The research suggests that the duration of light exposure, its intensity, and spectral composition, all affect sleep characteristics such as the quality and quantity of sleep, sleep architecture, and timing. The circadian rhythm regulates each element of sleep with its drives for wakefulness and sleep pressure subsequent to the wakeful period.


The brain receives information about light exposure through the eyes (optic nerves) and sends instructions to other biological systems. For instance, the notice prompts the body to reduce melatonin (sleep hormone) production and an increase in alertness and body temperature follow. Conversely, when it is dark, the levels of melatonin rise, accompanied by sleepiness and a drop in body temperature.


In the 2001 study, researchers looked at 5 astronauts before, during, and after two shuttle flights. They found that due to the shift in circadian rhythm, the participants showed a notable decline in neurobehavioral performance (psychomotor skills, cognitive performance, memory, focus). The extraordinary light-dark cycles during the space travel caused subjects to suffer hormonal imbalance attended by sleep loss, and reduced subjective sleep quality.


Here on Earth, office workers face similar challenges. A work environment that is enriched with artificial light can be detrimental to the employees’ health and diminish their quality of sleep.


The study published in The Journal of Clinical Sleep Medicine examined how office lighting affects occupational health. The participants were 49 day-shift workers split into 2 groups: one group worked in the windowless workplace and the other in the space with windows. The group that was exposed to the artificial work-place lighting reported higher scores when tested for sleep disturbances and slept almost an hour less than their counterparts.

Gadgets carved their way into our lives and needless to say, we are all hooked on updates, notifications, and alerts. Still, tablets, phones, TVs, laptops, and LED lighting are blue light emitters, controversial wavelengths with as many benefits as the perils.


Scientific evidence indicates that exposure to blue light can not only damage the sight, but it suppresses melatonin (a sleep-inducing hormone) delaying and reducing REM sleep (stimulates areas of the brain responsible for learning and memory consolidation), and increases levels of cortisol (the stress hormone) hampering deep sleep phase (slow-wave sleep, the most restorative stage of sleep).


Lighting technology, working environment, and sleep hygiene influence the amount of shut-eye you get per night, leaving their mark on your overall health and quality of life. Artificial nightlights disrupt the circadian rhythm and result in sleep deprivation and sleep disorders. Lack of sleep impairs hormone levels, impacts appetite and metabolism and erodes performance, productivity, and alertness. Insufficient sleep raises the risk of errors and injuries and consequently, affects safety.

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