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.

Urgent:  Ocean 'Secret' is 8000x more Powerful than All Superfoods (nutritional beast)

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.