Artificial Lighting Harmful to Sleep and Health

We hear a lot about the effects of light on sleep. Light in the evening—especially the blue light emitted by devices with screens—blocks secretion of the hormone melatonin, causing symptoms of insomnia. Low lighting during the day also delays melatonin onset and shortens the night.

Shift work, in which workers are routinely are exposed to light at night and must sleep during daylight hours, is so likely to disturb people’s sleep that the problem has its own name: Shift Work Sleep Disorder.

Not only do unnatural lighting conditions interfere with sleep. More and more evidence suggests that artificial lighting is behind the uptick in modern diseases such as cancer.

Insomnia and cancer are more likely in brightly-lit, urban areasWe hear a lot about the effects of light on sleep. Light in the evening—especially light emitted by devices with screens—blocks secretion of the hormone melatonin, causing symptoms of insomnia. Low lighting during the day also delays melatonin onset and shortens the night. Shift work, where workers are routinely are exposed to light at night and must sleep during daylight hours, is so likely to disturb people’s sleep that the problem has its own name: Shift Work Sleep Disorder.

Not only do unnatural lighting conditions interfere with sleep, say epidemiologists Richard G. Stevens and Yong Zhu. More and more evidence suggests that artificial lighting is behind the uptick in modern diseases, the topic of their recent opinion piece in Philosophical Transactions of the Royal Society of London B.

“It’s a new analysis and synthesis of what we know up to now on the effect of lighting on our health,” said Stevens in a University of Connecticut press release. “We don’t know for certain, but there’s growing evidence that the long-term implications of this have ties to breast cancer, obesity, diabetes, and depression, and possibly other cancers.”

In the Beginning

Humans evolved in an environment where the sun was the sole light source influencing internal circadian rhythms. The rising and setting of the sun determined when they slept and ate; it also set the rhythm for fluctuations in body temperature, gene expression, and hormone production. Sunlight in the daytime and darkness at night kept these systems cycling on a 24-hour day.

But the artificial lighting we spend our time in now is dim and poorly timed. Too little light during the day and too much at night lead to the disruption of circadian rhythms, insomnia, and increased susceptibility to disease.

Artificial Lighting and Cancer

Research suggests there is a relationship between exposure to light at night and breast cancer. Several studies show that women who work at night are more susceptible than women who work during the day. Night work is associated with melatonin suppression and, in women, higher levels of circulating estradiol, a reproductive hormone linked to breast cancer. Changes in the lymphatic system have also been observed.

Population studies, too, suggest a connection between breast cancer and exposure to light at night. Researchers in two studies used ambient light as measured by satellite at night to compare breast cancer risk across communities. They found a correlation between ambient light levels and breast cancer. “This has been tested and confirmed within Israel,” Stevens and Zhu write, “and among 164 countries of the world.”

Studies in molecular epidemiology also point to a relationship between circadian disruption and breast cancer. Long-term exposure to shift work alters patterns of gene expression throughout the body in ways that may increase breast cancer risk. Shift work may be a causal factor in colon and prostate cancers as well.

Do What You Can to Protect Your Health

You may be able to reduce your risk of developing these and other light-related health problems:

  • Get a healthy dose of sunlight during the day. If you can’t, buy a light box and use it.
  • Cut down on screen time at night. If you have a choice between an e-reader and a book, go for the book. Incandescent light is better than the blue light emitted by screens.
  • Use heavy curtains to block out all light sources when you’re sleeping.
  • Use red light if you must have light at night. (See my suggestion for red nightlights.) Firelight is circadian friendly for the same reason: it contains an abundance of red wavelengths.
  • Cut down on red meat to reduce the risk of colon cancer. Epidemiological studies show there is a correlation between eating red meat, which is high in iron, and developing the disease.

Blue Light's Effect on Sleep? It's Not All Bad

Blue light gets a bad rap these days in articles about sleepy teens. Exposure to blue light in the evening interferes with the secretion of melatonin (a sleep-friendly hormone), pushing circadian rhythms out of whack. This can lead to insomnia or sleep deprivation. Doctors are counseling teens and the rest of us to turn off devices that emit blue light—computers, tablets, and smartphones—in the run-up to bedtime.

This is sound advice as far as it goes. But the story on light is bigger than this simple warning suggests. Knowing how to manage your exposure to blue light can help you steer clear of sleep problems and increase your daytime stamina.

Blue light interferes with sleep and melatonin secretion at night but is beneficial during the dayBlue light gets a bad rap these days in articles about sleepy teens. Exposure to blue light in the evening interferes with the secretion of melatonin (a sleep-friendly hormone), pushing circadian rhythms out of whack. This can lead to insomnia or sleep deprivation. Doctors are counseling teens and the rest of us to turn off devices that emit blue light—computers, tablets, and smartphones—in the run-up to bedtime.

This is sound advice as far as it goes. But the story on light is bigger than this simple warning suggests. Knowing how to manage your exposure to blue light can help you steer clear of sleep problems and increase your daytime stamina.

“I Play Solitaire on My iPad at Night”

Screen time at night not just a temptation for teens. A grandmother I met the other day wondered if playing solitaire on her iPad in the middle of the night was contributing to her insomnia and making it harder to fall back to sleep.

I replied that it might be. Humans are most sensitive to the effects of blue light when our brains least expect it: late in the evening, at night, and early in the morning. The most intensive source of blue light is the sun. But the self-luminous screens of computers, iPads and iPhones emit blue light, too, at wavelengths that suppress melatonin. TV screens also emit blue light. But proximity to a light source matters. We position ourselves much closer to handheld devices and computers than we do to TVs, so the newer devices are more likely to interfere with sleep.

There’s an App for That

If you can’t bear to part with your iPad at night, there are ways to protect yourself from the light it emits. Dr. Craig Canapari recently posted an article containing helpful advice, and I’ll summarize it here:

  • Manually dim screens on devices at night
  • Visit Just Get Flux to download free software that automatically adjusts the color temperature of your computer screen according to the time of day
  • Get “night mode” software for your tablet or smartphone. The display will appear as white text on a black background.

You can also wear blue light-blocking glasses at night. A new study of teens shows that blue-blocker glasses with orange lenses allow for normal melatonin secretion and sleepiness to develop at night regardless of time spent looking at screens. But expect to pay more for these glasses than for a cheap pair of sunglasses with orange lenses. Cheap glasses will block blue light and other colors, too, so they won’t work well indoors.

Last but not least, use dim red lights as nightlights. Red light is least likely to suppress melatonin secretion and shift the rhythms of your body clock.

Soak Up the Rays During the Day

In the daytime, on the other hand, exposure to blue light is beneficial. Not only does it boost your attention, speed your reaction time and elevate your mood. It also helps you maintain a regular sleep/wake cycle.

But as the days grow shorter, you may miss out on daily exposure to the sun, a critical source of blue light. If you work in a windowless office, warehouse, or power plant and you commute in the dark, the daily resetting of your body clock enabled by sunlight does not have a chance to occur. Your circadian rhythms may go off track and your sleep take a turn for the worse.

A study just published in PLoS One illustrates this neatly. It was conducted at a polar base station at a time of year when crew members got no daily exposure to sunlight. Here’s what the researchers found:

  • When the subjects were working in standard indoor lighting for 2 weeks, they experienced a significant, 30-minute delay of melatonin secretion in the evening, and a decrease in sleep duration.
  • Working in blue-enriched white light for 2 weeks, they did not experience the delay in melatonin secretion. They slept longer and experienced a greater sense of wellbeing and alertness during the day. Daily exposure to blue-enriched light made the difference.

If you regularly miss out on the sun, consider investing in a light box, which will give you the daily dose of blue light your body needs. Better yet (but maybe something of a long shot), suggest the installation of blue-enriched white light at your workplace. The fact that it enhances work performance could sweeten the idea for the boss.

Have you noticed a seasonal pattern to your insomnia, where in the wintertime it tends to grow worse?

Seeing Red at Night

Results of a new study suggest that the color of the light you’re exposed to at night (think about the night light in your bathroom) can make a difference in how you sleep.

nightlightGoing away on vacation reminds me of all the ways my house is set up to help me steer clear of insomnia. Take the lighting situation at night. Even a 4-watt nightlight can put the kibosh on my sleep. So the nightlight in our bathroom is covered on two sides with black tape. I keep a small flashlight by my bed for use when I need to prowl around the house.

But I misplaced my flashlight one night up in northern Michigan, creating a tricky situation when I woke up needing to go to the bathroom. I decided to take a chance on feeling my way to the throne . . . only to slam into a wall. Nix to that!

But turning on the light was no better option. I shielded my eyes, but the fluorescent lighting flooded every nook and cranny of the bathroom and woke me up so completely that it took at least 45 minutes to fall back to sleep.

Better Lighting at Night

When you’re away from home, a small flashlight is probably all you need to get yourself to the bathroom and back with a minimum of arousal. At home, you can take other steps to assure that lighting has little impact on your sleep, and results of a new study, previewed in the blog Science20.com, suggest that the color of light at night can make a difference.

In this experiment conducted by researchers affiliated with The Ohio State University, white and blue light at night had negative effects on the behavior of female hamsters, and reduced the density of hair-like growths on brain cells that transmit chemical messages from one cell to another. Exposure to red light at night, on the other hand, had much less impact on the hamsters’ brains and behavior.

Red Light for Humans

These results may be applicable to humans, the study authors say. Red light in offices may be beneficial to night shift workers, and it may be less disturbing to hospital patients to be awakened to red light rather than white light at night. Red light may also be helpful in the home.

“If you need a nightlight in the bathroom or bedroom,” said co-author Tracy Bedrosian, “it may be better to have one that gives off red light rather than white light.”

This makes perfect sense to me. I hear a lot about how exposure to white and blue light blocks the secretion of melatonin and can delay the timing of sleep. But there’s never any mention of red light—which may be an even better answer to my home lighting needs than a nightlight covered with black tape.

What kinds of light seem to affect your sleep? Have you done anything to reduce your exposure to light at night?

Q & A: Summertime Insomnia & How to Beat It

Light and heat during the summer can make it harder to sleep, especially in people inclined to have insomnia. Here are a few things you can do to ease the situation.

Sleep more easily during the summer after a cold shower“Is it just me,” a reader wrote recently to Ask The Savvy Insomniac, “or do other people have more trouble with insomnia in the summer?

“I get in bed at the usual time but I’m not sleepy. I’m not worried about anything, I just can’t sleep. Then when the alarm goes off at 6 it feels like the middle of the night! I drag myself out of bed and drag around all day and it’s worse in this heat. But at night I still can’t sleep. It feels like I’m really messed up.”

It’s true that summertime can mess with sleep, especially in people inclined to have insomnia. But a few things can be done to ease the situation.

Adjust Your Exposure to Light

Light may be part of the problem. If you live in northern latitudes, you’re exposed to several more hours of daylight in the summer than in other seasons. Light in the evening delays the secretion of melatonin, a hormone that makes you sleepy.

One solution is to wear dark glasses in the evening, especially if you’re going to spend time outdoors. Blocking the blue end of the light spectrum is particularly important. So wear amber sunglasses that filter out blue light. And keep indoor lighting low.

Cool Down

The other problem in the summer is the heat. If body temperature regulation is an issue for you (it’s an issue for many people with insomnia) and you don’t have air conditioning, here are a few ways to beat the heat at night:

  • Use a window fan. Position it so that it faces outside and can draw cool night air through the house. It’s an old-fashioned remedy, but now that my A/C is broken, I’m reminded again of how well it works. (I live in Michigan, where temperatures at night are dipping into the 60s.)
  • Sleep in the basement or lower level of the house
  • Take a long, cool shower before bedtime.

Paradoxical as it may sound, another way to cool yourself down enough to be ready for sleep at night is to heat your body up some four or five hours before you normally go to bed. Vigorous exercise or a hot bath late in the afternoon or early in the evening will do the trick. Heating of the body and brain triggers an internal cooling mechanism, sleep scientists Dennis McGinty and Ronald Szymusiak have written. By the time your bedtime rolls around, you may well be cool enough to sleep.

If these measures fail, another option may be available in the not-too-distant future. Sleep scientists at the University of Pittsburgh are experimenting now with plastic caps designed to cool insomniacs’ overactive brains down at night and so promote sleep.*

These cooling night caps sounded totally unappealing to me last winter. But now that the summer heat has arrived, I say, bring ‘em on!

If you have trouble sleeping in the summer, what have you found that helps?

* E.A. Nofzinger and D.J. Buysse, “Frontal Cerebral Thermal Transfer as a Treatment for Insomnia: A Dose-Ranging Study,” Sleep 34, abstract supplement(2011): A183

LED Screens Harm Sleep

Use your laptop, tablet, or iPhone at night?

Electric lighting–particularly sophisticated devices with LED lighting–can seriously interfere with your sleep, says Charles Czeisler, a professor of sleep medicine at Harvard Medical School.

laptop-nightUse your laptop, tablet, or iPhone at night? Electric lighting—particularly sophisticated devices with LED lighting—can seriously interfere with your sleep, said Charles Czeisler, a professor of sleep medicine at Harvard Medical School in an article in Saturday’s Huffington Post.

“Technology has effectively decoupled us from the natural 24-hour day to which our bodies evolved,” Czeisler wrote this month in the journal Nature, “driving us to go to bed later. And we use caffeine in the morning to rise as early as we ever did, putting the squeeze on sleep.”

For some years now, I’ve known that light suppresses melatonin, the hormone secreted by the pineal gland that helps us fall and stay asleep at night. So at 9 or 10 p.m., I walk around dimming all the lights in my house. I try to create a sleep-friendly environment that allows me to drop off at a reasonable hour.

But research in the past couple of years is showing that LED lighting, found in devices that connect us to the Internet, is particularly harmful to sleep when we’re exposed to it in the evening and at night.

What’s So Bad about LEDs?

The human eye is composed of cells that enable vision but also has cells whose sole purpose is to detect light. These cells contain melanopsin, which is extremely responsive to the blue and blue-green light found abundantly in daylight and in LEDs. Blue light striking these melanopsin-containing cells suppresses the secretion of melatonin and sends a message to the brain that it’s still daytime, making it harder to fall asleep.

But LED screens on phones and laptops are fairly small, so you might wonder how they could have the same effect on the brain as daylight. After all, TV screens also emit blue light, yet Americans have been nodding off to late-night movies and comedy shows for decades.

Proximity is the critical difference here, according to Harvard Medical School sleep researcher Steven Lockley, quoted last year in an article written for the McClatchy-Tribune News Service.

“The closer you have a light source to the face, the more intense it is,” said Lockley, co-author of Sleep: A Very Short Introduction, “And the further you go away, it falls off quite quickly. So having things [laptops, tablets, and iPhones] close to the face is much worse than having a TV that’s 10 feet away.”

Quick Fixes

Minor changes can help you avoid the harmful effects of blue and blue-green lighting at night:

  • If devices have a “settings” feature, adjust the brightness of the screen and switch to the “white on black” mode in the evening
  • Purchase an app that automatically lowers the color temperature on your computer screen at night
  • Wear amber glasses that filter out blue light.

But the best solution is to turn all such devices off two hours before bedtime, when melatonin secretion normally begins. If you’re an insomniac like me, you’ll want to remove as many barriers to sound sleep as you can.

Do you use LED lighting and, if so, have you noticed it has an impact on your sleep?