New technology and research on circadian rhythm dysfunction has opened up opportunities to apply therapy using blue spectrum light to help reset the body clock.
What is blue spectrum light and why does it matter to sleep?
In this blog, we've previously discussed circadian rhythms and how they rely on light cues to help us regulate our sleep-wake cycles.
For those who suffer from circadian rhythm disorders, the use of light therapy—especially with blue spectrum light—has become a nonpharmacological way to help people "reset" rhythms that have shifted from normal schedules.
Why is blue spectrum light singled out?
While most visible wavelengths on the light spectrum can reset the body clock, the most efficient way to alter circadian rhythms is by using blue light.
Research suggests that circadian rhythm misalignments are a growing problem.
Dieter Kunz, director of the Sleep Research and Clinical Chronobiology Research Group at Charité–Universitätsmedizin Berlin, said that “a growing body of evidence suggests that a desynchronization of circadian rhythms may play a role in various tumoral diseases, diabetes, obesity, and depression.”
It's also responsible for our national problem with sleep debt and sleep deprivation.
While white light has long been used to help treat mood disorders, blue light has emerged as a two-for-one application, for treating both circadian rhythm disorders and mood disorders—which sometimes go hand in hand.
Wait... Isn't blue spectrum light bad for sleeping?
Yes! If you have normal healthy sleep, you can actually do yourself a disservice by exposing yourself to blue light at inappropriate times.
The most common sleep hygiene problem we have in the US is using devices with backlit screens right before bedtime. This includes smartphones, tablets, handheld games, laptops, even close-range TVs.
What's worse, we're taking gadgets to bed with us, and using them in the dark. This is problematic: blue light immediately stops the brain's pineal gland from releasing a natural hormone, melatonin, which is critical for the onset of sleep.
This naturally occurring melatonin should be released approximately 2 hours prior to your natural bedtime. Without it, the body cannot launch into sleep.
The large numbers of insomniacs posting comments online at 2 am is evidence enough: we need to adopt best practices at bedtime to remove these hazards. Using blue-light filters on our devices and wearing blue-blocking glasses with UV-protective, orange-shaded lenses are two solutions, if putting gadgets away is impossible.
Three circadian rhythm sleep disorders which benefit from blue light therapy
Delayed sleep phase syndrome (DSPS). People with this circadian rhythm disorder go to bed 2 or more hours later than everyone else, and not by choice.
This also means they naturally wake up 2 or more hours later than everyone else, which can wreak havoc on their lives if they are employed, have family obligations, or school to define their morning activities.
Using light therapy for DSPS consists of morning exposure to reset circadian rhythms.
Advanced sleep phase syndrome (ASPS). These people have personal rhythms that dictate that they fall asleep 2 or more hours before everybody else. Many elderly people have ASPS. When younger people experience ASPS, they find they are missing out on social lives and relationships because they can't stay awake late enough at night.
This also means they rise at least 2 hours before everybody else, which may be easier to manage than DSPS, but can still be significantly disorienting.
Using light therapy for ASPS means applying therapy in the later part of the day.
It stimulates wakefulness and delays premature production and release of melatonin until a much more appropriate time in the evening.
Insomnia. Insomnia disorder is not a circadian rhythm sleep disorder, per se, but it is often misdiagnosed when people suffer from the sleep phase disorders mentioned above.
Other sleep disorders may also warrant the occasional use of phototherapy: jet lag, free-running or Non-24-hour sleep-wake rhythm, shift work disorder, and SAD.
Blue light sources
The sun is still the brightest light we can expose ourselves to.
Even on a cloudy day, the brightness from natural light still eclipses anything you can expect from ordinary home lighting.
Yes, this means that even on a foggy or overcast morning in Seattle, you are still getting a lot more bright light outside than if you were to duck into a coffeehouse for a latté.
A common recommendation for people with all kinds of sleep disorders is to go outside for 20 minutes every morning as a way to enhance or reset rhythms.
Light Box (aka "happy light"): This is the most common light therapy application, and it resembles a large square or rectangular box emitting bright light.
Desk Lamp: This is a "happy light in disguise." It's suitable for using in an office setting where it can be placed close to your workspace.
Light Visor: This looks like a sun visor with lights that shine above and over the eyes. Useful for people who need to move from place to place throughout the day.
Dawn Simulator: These newer lights are often placed on the bedroom nightstand to mimic sunrise (some will mimic sundown as well). There are also new side tables that have the lights built into their surfaces to slowly change lighting depending upon the time of day.
Using blue light therapy involves answering two basic questions: "How much light intensity?" and "How much light exposure?" Here are some observations.
Lux is defined as the measure of how much light your eyes receive and perceive. Higher lux levels have become the norm in light box treatments. Between 8,000 and 12,000 lux is a pretty common concentration to expect from most therapy lights.
However, keep in mind that your distance from applications of light exposure are key to success. Staying within the range of 18 to 24 inches is recommended.
On the other hand, if you sit 4 feet away from your light, the intensity of your light therapy can be diminished by as much as 75 percent.
It's worth noting here that you don't have to look directly at the light for it to work; you just need to have your eyes facing the light.
Recent research in a study published in SLEEP shows that it's not the intensity of the light that matters as much as the amount of time exposed to it. Phase shifting does not seem to increase with the increase of lux units, but spending more time in front of the light does.
However, researchers still can't agree on the perfect lux level or duration for light therapy (though 10,000 lux is the most common intensity cited). Instead, they mostly encourage users to try larger boxes so that it is easier for them to stay within the therapy's visual range.
Does light therapy work?
According to the Circadian Sleep Disorders Network, sometimes. Users may find using light therapy allows them to return to the 9-to-5 schedule. Others have partial success, shifting up to 2 hours in the direction they need, but not more than that. Others find that they can achieve a normal sleep-wake cycle, but it's not all it's cracked up to be.
A note about side effects
While light therapy is considered safe, it does not come without its adverse reactions. Some users report trouble with their eyes, hyperactive behavior, stomach upset, headaches or migraine, and dry skin after using light therapy.
Using light therapy should take place under the supervision of a doctor; "self treating" could actually worsen your sleep phase problems. If you have other medical issues, you might aggravate them as well. Someone with bipolar depression, for instance, cannot use light therapy without risking the trigger of manic episodes.
Just because light therapy is not a drug does not mean it's a safe choice for everyone. It's better to be safe than sorry. A knowledgeable sleep specialist should be included in your treatment protocol to ensure you get the most appropriate light therapy plan for your specific concerns.
American Academy of Sleep Medicine
Circadian Sleep Disorders Network
Environmental Health Perspectives
National Sleep Foundation