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Treatment of Circadian Rhythm Sleep Disorders


Chronotherapy means rescheduling or shifting sleep/wake patterns in the hope that out-of-sync rhythms could be gradually pushed back to their normal pattern. This therapy was first used when researchers discovered circadian rhythm disorders, but didn’t recognize that circadian rhythms weren’t self regulating; they depended on external signals or ‘zeitgebers’ to reset each day. Without knowing what these zeitgebers were, researchers were unable to effectively manage circadian rhythm problems.


In the early 80’s, Dr’s Lewy and Sack at the National Institutes of Health discovered that melatonin was closely related to circadian rhythms, and that measuring melatonin levels was an accurate indication of what was happening to these rhythms. If that was the case, why not take melatonin tablets at certain times to push rhythms back to normal? This seemed to help, but it was apparent that melatonin alone couldn’t sustain a normal rhythm and that a more powerful signaler was needed.

Light Therapy

Circadian rhythm research took a giant leap forward in the late 80’s when researchers discovered that Seasonal Affective Disorder (SAD) was really a circadian rhythm disorder. (SAD sufferers have circadian rhythm sleep problems and feel worse at a particular time of day). Light had already been proven to be the most effective treatment for SAD, and now researchers realized that specialized light could control circadian rhythms. But they also learned that timing of light was very important, and that a combination of chronotherapy (shifting schedules), specialized light, and sometimes melatonin was the most effective way to treat circadian rhythm disorders.

Timing and the brain’s safety valve

The problem isn’t always lack of sunlight but timing of light. Since light causes hormonal changes, and too much light could over stimulate the body clock, it gradually shuts down its receptivity to light. After awakening, the body clock’s response to bright light lessens until light received after two hours is ineffective. This is why circadian rhythm sleep disorders aren’t dependent on geography; for example, you could get a flood of light in Phoenix and still have a circadian sleep problem because you didn’t get light at the right time of day.

Timing is Everything

When we don’t get the light signals we need, our body clocks malfunction, but because our body clocks react differently, we need light at different times. Remember that light can either advance or delay your body clock, so it is very important to know the right time of day to use the light. Using the light at the right time will mean the difference between responding quickly (within a few days), or experiencing a negative response. Researchers recognize the need for proper timing, and recently reported a two fold increase in response to light therapy when proper timing was used.

Perfect Timing

Knowing when to use the light is critical, and it can also be very confusing. An excellent general sleep self-assessment is available, and if you have symptoms that are suggestive of a circadian rhythm disorder, an additional assessment test is offered that can help you resolve any questions you might have about timing. This assessment tool determines which circadian rhythm disorder you may have, and it plots your rhythm over a normal one, so you can see how much correction you need. The assessment also determines the severity of your disorder and creates a personal treatment schedule for optimal results.

Type of light

In addition to timing, it turns out that the type of light is very important. Very bright light has been shown to work, but it may also be inefficient and may over-stimulate the rod and cone cells. Recent discoveries show that the melanopsin photoreceptor is responsible for mediating the circadian response, and melanopsin responds to a specific wavelength of blue light. This wavelength discovery is called the ‘action spectrum’ of light.

Advances in light technology

In conjunction with these discoveries, a new lighting technology was developed, which delivers the effective bandwidth of light while eliminating all other wavelengths. As a result, this newBLUEWAVE® technology is more effective at stimulating melanopsin cells than conventional light, and with greatly reduced intensity and side effects. Because BLUEWAVE® only produces the effective wavelength of light, it is 25 times less intense than 10,000 lux light.

BLUEWAVE® may be significant because it may cause a quicker stimulation, and thus take less time to use than conventional light. This process is called ‘spatial summation,’ and it describes the process of saturating melanopsin cells with light. As these cells become saturated, they signal the body clock to reset its rhythm. Since B isn’t competing with other wavelengths of light, this process happens much quicker. In addition, a small, hand size unit can produce sufficient quantities of blue light, in fact more than traditional full-size light boxes, so that treatment times are not only shorter, they are much more convenient and portable.

The Talk About Sleep Mission: to be a world leader in the sleep field by providing quality information, support and resources to sleep disorder patients, their family, friends and healthcare professionals.

Comments (1)

  1. Please provide reference for assessment tool for timing of bright light therapy which is referred to in the section. Perfect Timing

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