Everything You Need to Know About How Light Affects Your Sleep

Modern life is all it takes to find a way to overcome our inability in a new way. We’re not made to fly, live 20 stories in the air, or talk to a friend in New Zealand. And (murder alert) we must not stay awake when the sun is not shining. Of all we can do now, the latter may be the most versatile. If we have mastered something, then it is light. For the most part, this is good news; extra hours per “day” means we can communicate longer and do more work.

This post originally appeared on the Van Winkles website .

The problem is that evolution has programmed the human body to equate light with wakefulness. Our eyes perceive the intense blue light – like the soft light of an iPad – like the midday sun. If interior lighting (damn it, even fire) kept us awake long before nature goes to sleep, the constant glow of our devices is just another nail in the coffin of the legendary eight o’clock night. The problem is widespread: by some estimates, about 95 percent of Americans use the device within an hour of sleeping.

Therefore, until we move beyond the light-regulated circadian rhythm of sleep / wakefulness – or until some dystopian future makes daylight hazardous to our health – we need to embrace the relationship between light and sleep and understand what we can do. to help this. Here’s how to do it.

Why are we like this

Our body’s sensitivity to blue light has more to do with the composition of the earth than with the color of the light itself. Blue waves can penetrate the ocean surface better than others, allowing them to reach life where it originated. As species roamed overland, the reflectivity of the sky perpetuated life’s dependence on blue light to tune the cycle. (Maybe if humans evolved on Mars, we would develop a similar reaction to red light?)

This evolution has created a complex channel that translates light into signals that guide our circadian rhythm. A small fraction of the photoreceptor cells in our eyes contain a protein called melanopsin, which activates in response to intense blue light. When triggered, melanopsin transmits signals to the region of the suprachiasmatic nucleus of the hypothalamus – the so-called main body clock – located behind the root of the nose. In turn, signals are transmitted to the pineal gland and suppress the production of the sleep-inducing hormone melatonin.

But despite these adaptations, the human body remains slightly out of sync with the Earth’s 24-hour cycle. If left unaffected by sunlight, several studies have shown that the human clock will run on average in a 24.2-hour cycle. This means that if you are locked in a room with no windows and left to sleep and wake up of your own accord, your clock will shift 15-30 minutes for each day of isolation; during the month, day and night will switch places.

Daylight is the key to keeping the rhythm in check. “Every day, when you get up, you reset your biological clock,” explains Mariana G. Figueiro , program director of the Lighting Research Center at the Rensselaer Polytechnic. “You are increasing the time of your biological clock so that it works for 24 hours, not 24.2 hours.”

This is why morning light, which is rich in high-intensity blue waves, is most important in maintaining our circadian rhythm. During sleep, melatonin levels peak when body temperature drops to a minimum. At this point, ideally around 5 a.m., sunrise provides a melatonin-suppressing dose of blue light that helps the body wake up and synchronizes it with local time. This is why if we wait until noon to open the curtains, it will become more difficult to keep the schedule. “If we give light at the wrong time, it’s bad,” Figueiro says, “[but] if we don’t get enough light during the day, we will also be naughty.”

When evening falls, blue waves scatter and become more blurred, giving way to yellow, red and pink, which we associate with sunset. This warmer light does not activate melanopsin, which allows our bodies to produce melatonin and fall asleep easily.

Struggle for control

Of course, as scientists determine the mechanisms that govern how the relationship between light and sleep should work, natural, geographic, and technological factors conspire not to work.

For example, as we age, the way our eyes perceive light changes. In a series of studies, most recently published last year , Figueiro found that adolescents aged 15-17 are more sensitive to blue light (and therefore suppressing melatonin production) than other age groups; when exposed to light from devices such as phones and tablets, melatonin levels dropped 38 percent in the two hours before bedtime. This hypersensitivity is almost erased by the time we turn 20. Later in life, changes in the lens, such as yellowing or cloudiness, can block the absorption of blue light, making it difficult to wake up and stay alert.

Our location on the globe can also play a key role. According to Anne-Marie Chang, who studies environmental influences on sleep at Pennsylvania State University, people living close to the poles, where daylight hours either increase or decrease depending on the time of year, will eventually adapt and be able to maintain normal lives. eight hour sleep cycle. However, people visiting these areas or traveling across time zones will have a harder time. People suffering from jet lag know all too well this feeling of moodiness, lethargy, and instability.

“You can adapt to the effects of light depending on your environment, depending on the history of the exposure you have had in the past,” says Chang. For example, when changing time zones, research shows that you can go back to a two-hour time difference in four days or less – assuming the accumulation rate is 30-60 minutes every day.

Such seasonal and geographic disruptions make electric lighting a bit of a gimmick-22. While they allow, say, Scandinavians to work full days in the darkness of winter, they also make it much easier to completely ignore the body’s natural cycle. Artificial light allows us to work, play or tinker long after our body wants to start producing melatonin and getting ready for sleep. Insomnia and partying at night, once thought to be only to blame for the full moon , can now be a daily occurrence. “Maybe lighting actually helps because it allows you to disrupt your sleep?” the wonders of Figueiro.

This is a fair moment. But living in the dark after sunset is something that even cavemen could not stand (after all, they discovered fire), so we have to pay more attention to what kind of light is nearby and when. Naturally, there is no shortage of technical solutions that change color to synchronize the light with our circadian rhythm, but we don’t have to replace, calibrate, and plan every light bulb in our homes to survive.

During the day, this means paying attention not only to the color, but also to the direction and intensity of the light. Photoreceptors containing melanopsin (remember that convenient protein?) Are clustered closer to the bottom of the retina, making them most sensitive to light entering the eyes. Sunlight (yes) reaches them easily; Likewise, artificial lighting in offices, schools and hospitals works best when it comes from above. At the same time, the melanopic response requires bright light as much as blue.

At night, the opposite is true. This means dimming the light and eliminating the overhead in favor of table lamps that work to prevent as much light from reaching the melanopsin receptors as possible. Bad news: E-books, phones, and backlit tablets that shine directly in your eyes are prohibited, but old paper books are okay.

“If you are reading a book with a lamp, this light source is directed towards the page or away from you; you don’t look directly at it, ”says Chang.

More bad news: activating Night-Shift or another color-changing app doesn’t mean jailbreak; changing color without diminishing brightness will still stop melatonin production.

Now for some good news: According to Figueiro, jet black is not a necessity. A little street light or a night light in the hallway shouldn’t confuse you. “The circadian system is blind to this light. Better to have a 7-watt warm-colored night light than trying to navigate in the dark, ”she says.

Ultimately, experts agree that we must accept our body’s response to light. It is not something that we can ignore or innovate. In fact, the more we try to hack, dodge, or otherwise disrupt our natural pattern, the more we attune ourselves to the eternal Monday case.

How to use the power of light for better sleep “wiki useful Van Winkles


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