The disruptive effects of artificial light on sleep are well
and have received
an increasing amount of attention in recent years—with good reason. Nighttime
exposure to artificial light—which for the great majority of us happens without
much thought or awareness—disrupts the body’s circadian rhythm, altering
the 24-hour biological clock that controls our sleep-wake cycle. In addition to
wreaking havoc with sleep, disruptions to circadian rhythms also have been
associated with a number of serious diseases, including cancer, diabetes,
and heart disease.
In particular, research in recent years has shown that blue
wavelength light is especially harmful
to circadian rhythm function. Studies have shown that blue
wavelength light has uniquely harmful effects on humans, and suppress melatonin
levels more vigorously than other light wavelengths. Unfortunately, many
produce high concentrations of blue light. Blue light is emitted by electronic
devices, energy-efficient light bulbs, and other common light sources.
Research investigating blue-light blocking—most often in the
of goggles that filter out this particular wavelength of light—has shown
promise. A new study of
cataract patients indicates that artificial lens implants can help improve
sleep. Scientists at China’s Sichuan University studied the effects of
blue-light blocking artificial lenses implanted during cataract surgery. The
study involved 40 patients who required surgery for cataracts in both eyes.
Cataract surgery commonly involves
removal of the eye’s damaged lens, and insertion of an artificial lens.
Cataracts are a common condition among older adults—approximately 60% of people
over the age of 60 experience cataracts. The study subjects—26 women and 14
men, with an average age of 74—were given artificial lenses with blue-light
blocking capability. Researchers assessed patients sleep quality before surgery
and again two months after surgery. They found patients’ sleep had improved
significantly across several measures:
were sleeping more during the night
sleep quality had improved
levels of daytime dysfunction due to sleepiness had diminished
number of subjects who met the criteria for “poor sleepers” had decreased
Lens replacement surgery is necessary for cataract patients.
But there are other, less invasive ways to filter out blue-light that are also
being investigated by sleep scientists. Research has shown the benefits to
sleep of manipulating and controlling exposure to blue light:
- A study of 20 adults
who wore either blue-light blocking or ultraviolet-light blocking glasses
for 3 hours before sleep found that both sleep quality and mood improved
among those in the group who wore blue-light blocking glasses, compared to
the ultraviolet-light blocking group.
workers are at especially high risk for circadian rhythm disruptions,
because of their non-traditional schedules. In a study by scientists at
Quebec’s Universite Laval, nightshift workers used blue-light
blocking glasses at or near the end of their overnight shifts for 4 weeks.
At the end of study period, their overall sleep amounts increased, as did
their sleep efficiency.
nighttime exposure to blue wavelength light is damaging to circadian
rhythms, exposure to blue light isn’t always detrimental. Daytime exposure
to blue light can stimulate alertness and help sleep later on. A study of
94 office workers found
that daytime exposure to blue light during work hours resulted in
improvements both to sleep and to daytime functioning, compared to
exposure to white light. Subjects who were exposed to blue light
experienced improvements to daytime alertness, mood, and concentration.
These subjects also experienced decreases in daytime sleepiness and they
slept better at night.
This area of research is critically important, and I expect
we will see a great deal more investigation into the effects of blue wavelength
light on sleep and health. But you don’t need special goggles or eye lens
implants to protect your circadian rhythms and your sleep from the negative
effects of artificial light. Here are some low-tech suggestions that can help
exposure to artificial light in the hours before bed. The last 1-2 hours
before bed should be a time of winding down and preparing for sleep.
Decreasing your exposure to light is an important part of this process.
You don’t have to sit in a pitch-black room, but you should think about
beginning to limit your exposure to bright lights, whether from your
computer screen or your television. Reading under moderate lamplight is
fine. If you’re using a tablet to read, bring the screen’s brightness
level down. Make the last 60 minutes of your bedtime ritual electronics
free—and keep electronic gadgets and devices out of the bedroom
light exposure during the day. Daytime exposure to light—both sunlight and
artificial light—can help strengthen circadian rhythms and boost daytime
alertness, leaving you better prepared to sleep when the time comes.
- If you
need access to light in the middle of the night, use small nightlights.
Rather than switching on hallway or bathroom lights—and flooding your
system with melatonin-suppressing light—use low-illumination night lights
to guide you when you need to get up in the dark.
Being aware of the effects of nighttime exposure to
light and making some basic changes to bedtime routines can go a long way toward
getting you the darkness you need to sleep well, even in this ever-bright
Michael J. Breus, PhD
The Sleep Doctor®
Everything you do, you do better with a good night’s sleep™
twitter: @thesleepdoctor @sleepdrteam