Because the circadian rhythm controls the sleep/wake cycle, circadian rhythm disorder often results in insomnia. If there is a pattern to the sleep disturbance, i.e., one consistently wakes up or falls asleep at the wrong time, or if he/she cannot get to sleep at certain times, it is most likely that his/her circadian rhythm is malfunctioning.
The American Academy of Sleep Medicine (AASM) estimates that 25% of all sleep problems are directly related to circadian sleep disorders and several other sleep problems are either caused by or contribute to circadian rhythm disorders. These sleep disorders include late night and early morning, insomnia, interrupted sleep patterns, free-cycling sleep disturbances and irregular sleep disorders. (For specific information on all circadian related sleep disorders, visit the sleep section on this webpage.) The two most common sleep problems—Late night and early morning insomnia are discussed below.
Late Night Insomnia
The majority of people with sleep problems experience difficulty being able to fall asleep. They may only experience a few hours of sleep each night, and feel worse in the morning time. In this case, the body clock is running slower than a normal circadian rhythm (24 hour period). The clinical term for late night insomnia is Delayed Circadian Rhythm Disorder or DCR. DCR sufferers’ body clock doesn't 'wake up' until later in the morning or day. They have difficulty getting started in the morning, may feel a bit groggy or down during part of the day, and may experience a second wind later in the evening. Those with DCR are often referred to as night owls, and find it easier to stay up late at night.
With DCR, the daily cycle, or circadian rhythm is running slow, and the pineal gland releases the nighttime hormone melatonin too late, causing sleep to occur later. In the morning, the body clock is still producing the nighttime hormones. This is why it may take several hours to feel active and energetic. Because DCR sufferers don't receive the proper amount of sleep, energy, alertness and ability to function may also be diminished.
Because DCR is the result of a slower circadian rhythm, bright morning light is the most successful means to speed the body clock up and restore circadian rhythms to their normal function. Because DCR disorders vary with individuals, the treatment schedule needs to be adapted accordingly. Apollo provides an effective assessment tool on its website for determining the proper treatment schedule and guidelines.
Early Morning Insomnia
As people age, they tend to have difficulty staying asleep, and usually awaken hours before dawn. Those with early morning insomnia generally tire easily in the afternoon or evening and have little difficulty falling asleep. The clinical term for this disorder is Advanced Circadian Rhythm Disorder or ACR. ACR happens when the body clock is running faster than a normal 24-hour period. Because the body clock is running too fast, ACR sufferers tend to run out of energy before the 'day' or 24 hour period is through. ACR also tends to compress the sleep portion of the daily cycle, causing ACR sufferers to often sleep less than 8 hours per night.
Because the circadian rhythm is running fast, the pineal gland releases the nighttime hormone melatonin prematurely, causing one to feel tired earlier in the evening. Since melatonin is released prematurely, the body clock can't sustain a complete sleep cycle, causing early insomnia.
Bright evening light has been shown to be the most effective treatment for ACR. Evening light slows the body clock down to a normal rhythm. This delays the onset of melatonin and sleep, allowing the person to sleep longer and have more energy in the late afternoon and evening.
CRD's contribute to other sleep disorders
Circadian Rhythm Disorders keep our bodies from enjoying a complete or rejuvenating sleep. Because CRD's disrupt the sleep pattern, they may contribute to narcolepsy, sleep apnea, snoring, etc. Most people find these symptoms diminish when their circadian rhythms are working properly
Light Treatment for Sleep Disorders: Consensus Report. IV. Sleep Phase and Duration Disturbances
J Biol Rhythms
Terman M, Lewy AJ, Dijk DJ, Boulos Z, Eastman CI, Campbell SS
Advanced and delayed sleep phase disorders, and the hypersomnia that can accompany winter depression, have been treated successfully by appropriately timed artificial bright light exposure.
Treating Chronobiologic Sleep and Mood Disorders with Bright Light
Alfred J. Lewy, MD, PhD
The study of circadian rhythms and their effects on biological functions and mood have provided fascinating insights into the understanding of mental illness. 10 Treatment Guidlines for using bright light.
Understanding How Bright Light Affects Circadian Rhythm Disorders
Apollo Health Inc.
Mood and sleep disorders have chronobiologic basis. Using therapeutic light to treat sleep disorders often resolves or mitigates the mood problem. Light must be used at the proper time of day for desired effect. Explanation of when and why to use bright light.