Light affects melatonin, a hormone that helps regulate sleep. The same is true for some blind people who do not consciously perceive light.
Researchers soon discovered why. Our retina contains specialized cells that are uniquely sensitive to light with a wavelength of about 460 nanometers, or blue light.
At dawn, the blue light from the morning sun stimulates retinal cells, signaling the brain to stop producing melatonin. Then, when the environment darkens and the blue light is replaced by the warmer shades of the setting sun, melatonin increases again, allowing us to sleep.
Scientists hypothesize that blue is important because the cells in the retina that perceive light first evolved among people who lived in the ocean. Wavelengths penetrate water more easily.
Blue light and circadian rhythm
The human eye has evolved according to these natural light conditions, but electric lighting (the incandescent light bulb was patented by Thomas Edison in 1880) disrupted the human circadian cycle. Modern society has led us to stay up late, work indoors for long hours, and sleep through the night instead of biphasic sleep, known as biphasic sleep (as it used to be).
We are now constantly exposed to blue light in the evening, from fluorescent lights in our homes and offices, street lights and headlights during rush hour, and screens and smartphones we stare at while lying in bed.
It had a huge impact on our sleep. A study of nearly 20,000 American adults found that those who lived in areas with more outdoor nighttime lighting, such as streetlights, went to bed later, slept less, and felt more sleepy during the day. There was found.
Karolina Zielinska Dabkowska, a lighting designer and assistant professor of architecture at Gdańsk University of Technology in Poland, says that the construction of skyscrapers in cities creates “urban canyons” that deprive us of natural light and affect our health. He said it had a big impact.
In addition to disturbing sleep, nighttime artificial light exposure is linked to breast and colorectal cancer, said Jelinska Dubkowska in an email interview. She “is also a risk factor for cardiovascular disease, type 2 diabetes, hypertension, obesity and depression,” she says.
There are several ways to regain control of your circadian rhythm.
“Getting sunlight in the morning can have a positive impact on your nighttime sleep quality,” says Zielinska-Dabkowska.
Your circadian rhythm is highly sensitive to light during the first hour after you wake up. To get the most out of your body clock, she advised exposure to blue-rich sunlight early in the day, ideally without sunglasses or contact lenses.
Take a walk outdoors in exchange for an afternoon latte
After lunch, the body will produce melatonin again. Some cultures accept the drowsiness caused by melatonin and recommend napping. Other cultures face this situation with tea, coffee, or the Boston urge to go to the nearest Dunkin’ at 3pm.
However, sunlight may block melatonin’s instructions to fall asleep. A study of college students showed that exposure to artificial blue light in the early afternoon not only improved post-lunch sleepiness, but also improved memory.
Check your home lighting
Move your desk to an area that receives the most natural light during the day.
Dim all lights at least three hours before bedtime.
Lighting should be subdued and less bluish. On July 31st, the United States will stop producing incandescent light bulbs (known for their warm, sunset-like spectrum), so unless you stock up on incandescent bulbs, replace fluorescent bulbs with amber LED bulbs, or preferably smart bulbs. is needed. These can be programmed to be bluer during the day and redder in the evening (aim for 2,700 Kelvin or less).
“The placement of the light source is also important,” says Zielinska-Dabkowska. She recommended avoiding overhead lighting, placing lamps low on the ground or table, and shaded to avoid looking directly into the light source.
Change your phone settings
Avoid screen time before bed. However, this is not always the case, so turn on the “Night Shift” setting on your iPhone or turn on the “Blue Light Filter” on your Android phone to adjust the color of your screen at night.
“These features don’t completely reduce blue wavelengths,” warned Zielinska Dabkowska, but “the impact of such devices is mitigated to some extent.”
Experts recommend keeping the lighting in your room to 1 lux or less while you sleep. This equates to a candle a little over 3 feet from your eye. If you get a lot of light pollution from outside your home, try a sleep mask or blackout curtains.
What we want our patients to know
In the short term, taking melatonin in small doses is usually safe, but there is a surprisingly high percentage of melatonin supplements that don’t contain what’s on the label. If you have insomnia, talk to your doctor about cognitive-behavioral therapy before trying pills. We recommend cognitive-behavioral therapy as the first choice because it can address the underlying causes of insomnia, as opposed to medications that target symptoms.
Physician Profile: Trisha S. Pasricha is a physician at Massachusetts General Hospital, a medical lecturer at Harvard Medical School, and a medical journalist.
Ask the Doctor: Do you have any health questions? The right experts will answer you.
Sign up for our Well+Being newsletter for expert advice and simple tips to keep you well
#Advice #Doctor #Sun #Sleep