Sleep
Say "No" to Night Light for Better Health
February 3, 2017
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They’re everywhere- in household corridors, in hospital hallways- but nightlights can
actually have a harmful effect on health. Exposure to light at bedtime and during sleeping
can lead to an array of health problems, according to studies.
The Problem
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The pineal gland is a small endocrine gland located in the brain. It’s shaped like a
pinecone, hence the name. The pineal gland produces melatonin, a hormone that
regulates sleep and wakefulness. Melatonin plays a role in the circadian rhythm, an
internal “clock” that helps regulate the sleep/wake cycle. Melatonin also prepares the
body for restful sleep by lowering blood pressure, glucose levels and body temperature.
Melatonin is produced when it’s dark, usually at night. Normal, healthy amounts of
melatonin are observed after sleeping several hours in complete darkness. Unfortunately,
most people don’t sleep in complete darkness. Glowing computer monitors, digital alarm
clocks, cell phone display screens or any other variety of modern devices can be found in
most bedrooms.
Even a small amount of light can interrupt the pineal gland’s production of melatonin,
causing rippling health effects. Whether it’s from a nightlight, a digital clock, a
smartphone or tablet, or even streetlights filtering through the bedroom curtains, exposure
to light at night (LAN) should be avoided.
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Avoid Nightlights, Streetlight
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Nightlights are commonly found in many houses. Whether used to comfort a child, provide guidance around furniture or help the family companion see, nightlights come in many different shapes, sizes and brightness levels. However, even the small amount of light from a hallway nightlight can interrupt melatonin production. The faint light can cause the pineal gland to mistakenly believe it’s daytime and interrupt melatonin production.
The same is true of streetlights that shine in through your curtain windows. Often intensely bright, the filtered amount of light that seeps in through bedroom window blinds and curtains can delay melatonin production. Many people report an excellent night’s sleep when staying at a hotel. That’s probably because most of these rooms have blackout curtains to prevent any amount of light into the room, thus creating the perfect environment for melatonin production: pitch black.
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Smartphones and Tablets Can Harm
While it’s tempting to check Facebook before bedtime, studies show
https://www.sciencedirect.com/science/article/pii/S0003687012001159 that using back-lit devices like smartphones and tablets decreases melatonin production. After just 2 hours of use, melatonin production was reduced by about 22 percent in participants who used a tablet before bedtime. Without proper melatonin production, individuals are at increased risk for health issues such as obesity, breast cancer, Alzheimer’s, and fibromyalgia.
Links to Cancer
Studies have shown that female night shift workers have an increased risk to develop breast cancer, https://www.sciencedirect.com/science/article/pii/S0959804911005016and it was suggested this is due to reduced production of melatonin caused by exposure to bright, white light at night.
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To test this theory, researchers implanted rats with breast cancer xenografts and gave them blood from different women. Rats exposed to blood from women with low melatonin levels due to LAN exposure had an increase in tumor growth and activity http://cancerres.aacrjournals.org/content/65/23/11174. Conversely, rats exposed to blood from women with high melatonin levels saw a decrease in tumor growth rate and activity level.
In another study https://www.tandfonline.com/doi/abs/10.1080/07420520801921572, researchers looked at nighttime satellite images of 147 communities to determine light at night (LAN) levels. The communities with the highest LAN levels also had the highest breast cancer rate. The study demonstrated a strong positive association between LAN intensity and breast cancer risk.
The Bottom Line
The less amount of bright white light you’re exposed to at night, the better.
Limit the amount of exposure to bright white light before bedtime and don’t access electronic devices for at least an hour before bedtime.
If you must check your device during the night, be sure to turn down the brightness.
Sleep in a completely dark room and be sure the alarm clock lights and computer monitors are turned off.
Need to make a trip to the bathroom? Don’t turn on the overhead lights. Instead, use a small flashlight to find your way.
The text in this work is licensed under a Creative Commons Attribution 4.0 International License
Pineal Gland
