The Importance of Darkness to Your Health

In ancient times, and throughout most of human history, night used to be truly dark, and thus ideal for sleeping. While it’s true, of course, that the sun still sets every evening, most of us are exposed to a barrage of artificial light sources all night long. As it turns out, this can spell trouble for our health.

Even for those people living in the country or in rural areas, where street lights, city lights, and passing headlights are not an issue, electronic devices are a staple in modern homes. A body of research shows that the rise in the use of electronics is linked to negative effects on our natural sleep cycle.

It is now estimated that about 40 percent of Americans sleep less than seven hours per night — and that’s not enough.

Don’t underestimate the dark

According to the authors of a new study published by The Royal Society:

“Since the introduction of electric lighting, there has been inadequate light during the day inside buildings for a robust resetting of the human endogenous circadian rhythmicity, and too much light at night for a true dark to be detected; this results in circadian disruption and alters sleep/wake cycle, core body temperature, hormone regulation and release, and patterns of gene expression throughout the body.”

The “endogenous circadian rhythmicity,” often called simply “circadian rhythm,” of human beings is the body’s natural “clock,” or the set of processes that govern our sleep/wake cycles. Along with our sleep/wake cycles, circadian rhythm also dictates many other bodily processes, such as our body temperature, our hunger cycles, and our levels of energy.

So, how important is darkness to this cycle? It is crucial. When it gets dark, the body naturally produces more of the hormone melatonin, which signals to the body that it is time to sleep. When the sun comes up, melatonin levels lower, and the body is signaled to awaken.

However, when our darkness is compromised — either through artificial lighting, sleeping during the day due to a nigh-shift schedule, or living in a home that does not get a lot of natural light or darkness contrasts (such as a basement apartment), the body’s production of melatonin is compromised as well. This may lead to some potentially serious health issues, especially over time.

A good night’s sleep is crucial to good health

We all know that we just plain don’t feel good when we don’t get enough sleep. If we get less than that sweet zone of seven to eight hours, we find ourselves groggy, irritable, and not able to think clearly. If we pull an all-nighter, it’s not uncommon to experience notable decreases in cognition, shaking hands, and altered mood. Sometimes, we may even experience visual or auditory hallucinations.

Just a few other symptoms that may come from short-term sleep deprivation are depression, binge-eating (more on that to come), facial wrinkles, skin blemishes such as acne, and decreased sex drive. Chronic sleep deprivation has been linked to some very serious disorders: including an increased risk of obesity, diabetes, heart disease, fibromyalgia, stroke, Alzheimer’s disease, and cancer.

So, how much sleep does one have to lose to suffer serious effects beyond a brain fog? A recent study shows that losing as little as 30 minutes of sleep per night each weekday may increase one’s risk of type 2 diabetes, as well as obesity.

For this study, researchers analyzed the sleep habits of 522 individuals, who were instructed to keep a sleep diary each day for one year. The researchers found that after the 12-month period,”for every 30 minutes of weekday sleep debt at baseline, the risk of obesity and insulin resistance was significantly increased by 17 percent and 39 percent, respectively.”

Another study, published in 2014 in the journal Neurology, linked less-than-adequate sleep with increases in brain shrinking, especially in individuals over the age of 60. On these results, the study’s lead researcher, Claire Sexton of the University of Oxford, wrote:

“We found that sleep difficulties (for example, trouble falling asleep, waking up during the night, or waking up too early) were associated with an increased rate of decline in brain volume over 3 [to] 5 years. Many factors have previously been linked with the rate of change in brain volume over time — including physical activity, blood pressure and cholesterol levels. Our study indicates that sleep is also an important factor.”

The study authors added:

“Poor sleep quality may be a cause or a consequence of brain atrophy, and future studies examining the effect of interventions that improve sleep quality on rates of atrophy may hold key insights into the direction of this relationship.”

The link between sleep and memory

A recent study performed at Brandeis University in Massachusetts tested the brains of Drosophila flies, which are sometimes used by researchers because of their simple organ system structure, and its relationship to human systems. During their study, the researchers found that the same parts of the brain responsible for memory function also affected sleep.

On this relationship, Bethany Christmann, one of the study’s authors, stated:

“It’s almost as if that section of the mushroom body [a part of the Drosophila brain analogous to the hippocampus] were saying ‘hey, stay awake and learn this. Then, after a while, the DPM neurons start signaling to suppress that section, as if to say ‘you’re going to need sleep if you want to remember this later.'”

Christmann and her fellow researchers hope that this observation can help researchers better understand the relationship between memory and sleep in the human brain.

Lack of adequate sleep can also affect your weight

You may be wondering what the connection between lack of sleep and binge eating — which was mentioned above — is all about. It turns out that when lights are on, it not only lowers the body’s melatonin levels, but also its levels of leptin. This can lead to midnight cravings, especially for unhealthy foods.

On the subject, the authors of a 2004 study published in the Annals of Internal Medicine wrote:

“Sleep restriction was associated with average reductions in the anorexigenic hormone leptin, elevations in the orexigenic factor ghrelin, and increased hunger and appetite, especially for calorie-dense foods with high carbohydrate content.”

If you routinely binge-eat foods laden with refined carbohydrates, you can reasonably expect the pounds to pile on. It is especially unfortunate that wheat has been found to be highly addictive, which elevates the cravings even more.

Different kinds of light

darknessSo, we’ve established that darkness is essential for sleep — but do different types of light affect us differently? Absolutely. Research has shown that blue light — such as from the sun and fluorescent lights (think your tablet and cell phone) — keeps us awake the most.

On the other hand, red and yellow lights (from candlelight, and incandescent light bulbs) are naturally dimmer, and do not affect circadian rhythms as severely as blue light. While darkness in the bedroom is always best when trying to sleep, if you have alarm clocks or hallway night lights, you may want to keep them in this spectrum.

Getting back into the natural rhythm

How do we get back in line with our natural circadian rhythms? Here are a few tips to consider:

Take a camping trip! Being away from artificial lights, even for a couple days, can have an immensely positive effect — as long as you don’t take your electronics with you! A 2013 study published in the journal Current Biology studies this effect, and found:

“Electrical lighting and the constructed environment is associated with reduced exposure to sunlight during the day, increased light exposure after sunset, and a delayed timing of the circadian clock as compared to a summer natural 14 hr 40 min: 9 hr 20 min light-dark cycle camping. Furthermore, we find that after exposure to only natural light, the internal circadian clock synchronizes to solar time.”

Make sure your bedroom is as dark as possible. You may want to experiment with curtains, window shades, or even an eye shade. Keep electronic devices out of the bedroom — they’ll do nothing but keep you awake.

Go to bed half an hour earlier. As it takes most people some time to fall asleep, giving yourself an extra window to make sure you get a full seven hours actually snoozing is key.

Turn down the heat. Sleeping in a cooler bedroom (below 70 degrees F) is linked to promoting restful sleep. Plus, it may help to activate brown fat, a metabolically active type of fat that actually increases your body’s rate of calorie-burning.

Make sure your sleep position isn’t affecting your snoozing time — check out our article and see if your preferred position is working for or against you.

There’s an app for that. Check out these nifty sleep apps that have been developed for the singular purpose of promoting quality sleep!

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