A healthy individual normally sleeps 7 - 8 hours per night and is awake for roughly 16 hours. When this normal pattern is disrupted, it can cause problems in other areas of the person’s life. It makes it hard for them to carry on living a normal life because they sleep at odd times.
The circadian rhythm is the body’s natural clock that tells you when to sleep and when to wake up. If this clock is not working properly, the individual will be sleepy when they should be awake and alert. Their sleep-wake cycles will be out of sync. The circadian system works by phases of light and darkness and is easy to override with the use of artificial light and blue light from cell phones, laptops, and TVs.
Circadian rhythm disorders include:
- Delayed sleep-wake phase or delayed sleep onset phase
- Advanced sleep-wake phase
- Irregular sleep-wake rhythm
- Non24-hour sleep-wake disorder
- Shift work disorder
They are all under the circadian rhythm system, but each has different aspects. Here we will be discussing the irregular sleep-wake phase or ISWRD.
Irregular sleep-wake rhythm disorder is a type of circadian rhythm disorder characterized by lack of a regular pattern in a person’s sleep-wake cycle. This disorder is thought to be the result of decreased neuronal activity in the brain, which may be why it is seen in older adults with Alzheimer’s disease and dementia, although ISWRD is also seen in mental retardation and traumatic brain injury. Irregular sleep-wake disorder may result from lack of structured physical and social activity during the day and decreased exposure to bright light (or decreased responsiveness of the circadian clock to light and activity).
The symptoms of an irregular sleep-wake rhythm are:
- napping throughout the day and night with no regular pattern
- Sleeping intermittently or at odd times when one should normally be awake
- a hard time sleeping, or sleeping only for short periods, and being very sleepy when awake
- accumulating total sleep time that is beyond the normal range for one’s age.
Treatment of ISWRD and some other sleep-wake disorders involves trying to reset this body system by encouraging sleep during the night and wakefulness during the day. Accomplishing this means getting enough exposure to bright light during the day and activity to keep awake until the appropriate sleep time. These time cues will eventually take over and the system will return to normal. This is a process known as entrainment.
Studies of pharmacologic treatments for irregular sleep-wake disorder have generally shown inconsistent or negative results. In general, nonpharmacological treatments involving light therapy (increasing exposure to bright or daylight from outside), increased physical and social activities during waking hours, and improved sleep hygiene has had the most success at making significant changes.
Diagnosing irregular sleep-wake rhythm
The first thing to do is to see a doctor qualified to diagnose sleep-wake disorders. This disorder causes disruptions to the work-life balance. Daytime sleepiness interferes with concentration and having trouble to stay awake can cause problems in your work environment. Likewise, it can be hard to maintain personal relationships and family responsibilities.
When it affects older adults it often leaves them homebound and isolated. Sleeping aids or alcohol make the problem worse. It is easy to overestimate the amount of medication you need and taking too much can be disastrous, depending on what it is. This isn’t something you should try to treat yourself.
The doctor will ask you about your medical history, neurological disorders, and current sleep behavior (when you sleep and when you are awake). The doctor will ask about medications you might be taking, alcohol use, and your family history. Be honest about any past or present use of drugs, alcohol, or medications.
While you might not want to tell the doctor certain things, it may be important in diagnosing your condition and finding an effective treatment. Some medications and certain drugs are known to cause interference with sleep, and prolonged use can contribute to sleep disorders. Knowing this information could make a big difference in how quickly you get help.
Many factors can affect your sleep-wake cycles. One way to determine sleep habits is to do a sleep study or sleep diary to record your sleep patterns over some time. You may also be asked to wear an actigraph. This device looks like a wrist watch and is used to record active and inactive episodes over a few weeks.
The doctor will make his diagnosis of irregular sleep-wake rhythm based on the results of the sleep diary, medical and psychological evaluations, and hormonal indicators such as melatonin levels. Melatonin levels are often reduced in people with disturbances of the sleep-wake phase.
A sleep study or polysomnogram may not be needed unless you have other sleep disorders such as sleep apnea or the restless leg syndrome as contributing factors. If your doctor suspects that the cause may be from a neurological disorder, he may order blood testing, a CT scan, or an MRI to confirm.
Treatment of irregular sleep-wake rhythm
The goal of treatment of sleep disorders is restoring a routine of sleeping at night and staying awake during the day. SCN time cues, or zeitgebers, as they are called, are critical for this process to be successful. Patients with a sleep disorder need exposure to bright light during the day and to avoid it in the late evening and at night. This light includes artificial light from LED screens, electronics, etc. Besides the light, engaging in these activities also encourages you to stay awake longer in the evening than you should.
Physical exercise and social activities are strongly encouraged for daytime. Taking a walk, riding a bike, or doing yard work when the sun is out is optimal for getting the light exposure you need during the day.
Melatonin is a hormone produced naturally by the body. The levels of melatonin can sometimes be reduced by aging, diet, and some neurological disorders. Supplementation with melatonin is often effective in small doses for individuals with certain sleep disorders. There are times when it is effective and times when it shows no significant benefit.
A large scale trial of 157 Alzheimer’s patients found no significant differences in sleep results between a control group and those taking 2.5mg of melatonin. Improvement was seen when the dosage was increased to 10mg. Overall, the efficacy of melatonin treatment remains uncertain.
On the other hand, some have had success in using melatonin to treat sleep disturbances in children with presumed ISWR. A significant result was obtained in an open trial with 2 to 20mg of melatonin given at bedtime to children diagnosed with neurological disabilities and chronic sleep-wake cycle disorders. A recent study indicates that using a controlled-release melatonin formulation may be more effective for falling and staying asleep than the quick-release formulation.
A minimum of two hours of bright light per day (3,000 to 5,000 lux) for four weeks has shown to decrease napping during the day and increase nighttime sleepiness. Extended light exposure in the morning may encourage more nighttime sleep, decrease agitation, strengthen the circadian rhythm, and restore the balance.
Structured physical and social activity
A schedule of physical and social activities encourages daytime wakefulness and helps to increase a normal sleep-wake routine. Reducing nighttime light and noise helps individuals sleep longer after falling asleep. Daytime exercise, participating in social interactions or activities, and avoiding stimulation at night is helpful for reestablishing good sleep hygiene.
Therefore the most effective ISWRD treatments appear to be a combination of social and physical activity, increasing exposure to light during the day, and minimizing light sources in the evening before going to bed.
Exposure to light alone did not improve nocturnal sleep according to one study, but combining light with 5mg of melatonin increased daytime waking and activity levels and strengthened the rest-activity rhythm in patients with AD. A dose of 2.5mg taken in the evening improved cognitive function and increased sleep duration, but seemed to have an adverse effect on the mood of elderly residents in nursing care facilities.
Therefore the authors of the study recommend using melatonin in combination with light therapy. A combined treatment of light and melatonin in the study decreased agitation and aggressive behavior, and moderately improved sleep habits.
ISWR should always be a consideration when diagnosing sleep disturbances in older adults and children with neurological impairments. Individuals with ISWRD have problems with sleep maintenance and excessive daytime sleepiness. Decreased exposure to bright light, lack of social and physical activity, and poor sleep hygiene play important roles in the development of ISWRD.
Rapid advances in technology and our understanding of circadian rhythms will better identify genetic factors for ISWRD and aid in the prevention and treatment of circadian-based disorders.