What should I know about circadian rhythm sleep disorders?

This article details what everyone should know about circadian rhythm sleep disorders. People can have complaints of insomnia or excess sleepiness, depending on the problem with their life. - JR

When we think of sleep disorder, we tend to think of insomnia, but there are other sleep disorders that can affect a person's ability to work, attend school or live a normal life.

Your circadian rhythm is your body's "internal clock," which signals when you should sleep and when you should wake, as well as other body processes. Normally, this clock runs on a 24-hour cycle, which echoes the Earth's pattern of night and day. We sleep at night; we are awake during the day. However, sometimes our circadian rhythm becomes disrupted, making it difficult for people to sleep during the night or be fully awake and functioning during the day.

Some common causes are going on shift work, pregnancy, time zone changes, medications and changes in routine.

Some common circadian rhythm disorders are:

Jet lag or rapid time zone change syndrome: This includes excessive sleepiness and lack of daytime alertness in people who travel across time zones.

Shift work sleep disorder: This sleep disorder impacts those who frequently have to rotate work shifts or often work at night. They may have trouble adjusting to sleeping during the day and working at night, and this can lead to insomnia.

Delayed sleep phase syndrome: This disorder affects the timing of sleep. People with DSPS tend to fall asleep very late at night and have difficulty waking in time for work, school or other appointments.

Advanced sleep phase syndrome: With this disorder, a person goes to sleep earlier and wakes earlier than desired.

Non-24-hour sleep-wake disorder: With this disorder, a person has a normal sleep pattern, but they live in a 25-hour day. Over time, their sleep cycle is affected by inconsistent insomnia that occurs at different times each night. They may fall asleep at a later time and wake up later, or fall asleep earlier and then wake up earlier.

How are sleep disorders treated?

Treatment options vary depending on the type of sleep disorder involved. One of the first steps is ruling out side effects from any medications, as well as any underlying medical conditions. Having the patient keep a sleep diary for one or two weeks is also important. Often, a combination of behavior therapy, light therapy and possibly medication is involved in providing successful treatment.

Behavior therapy: This usually involves having the patient maintain regular sleep/wake times and avoid naps. This will help "train" the body to the proper sleep time. Engaging in regular exercise is also key as it will encourage physical tiredness. Patients are also advised to avoid caffeine, nicotine and other stimulants, as well as any intense exercise within several hours of bedtime.

Those suffering from delayed sleep phase syndrome should minimize exposure to light during the evening and at night by reducing illumination in their home, and by avoiding the bright screens of televisions and computers. For those suffering from advanced sleep phase syndrome, the situation is the reverse, with light exposure needing to be increased in the evenings. Typically, patients are advised to keep lights on indoors for a longer period, or to spend more time outside in the longer daylight months.

Medication: Medications such as melatonin, or short-term sleep aids, may also be used to adjust and maintain the short-term sleep cycle in order to shift it toward the desired schedule. Melatonin is available over the counter and is a hormone that is found naturally in the body. It promotes sleep and can help with short-term sleep issues. The proper timing of melatonin use varies depending on the condition being treated.

Chronotherapy: A behavioral technique in which the doctor works with the patient to gradually and systematically adjust bedtime until the patient is on the desired schedule. This can take one to two weeks to achieve.

Bright light therapy: Sleep therapists use bright light therapy to help reset a body's circadian clock. The patient is exposed to a high-intensity light (10,000 lux) and the amount of exposure is typically for 30 minutes upon awakening.

We often joke about not getting enough sleep, but for those suffering from true sleep disorders, this is no laughing matter. A good rest, and being able to sleep and wake on a regular schedule, are keys to our being able to function successfully in the world. Lack of sleep, or lack of a regular sleep pattern, can lead to depression, substance abuse and other mental health issues. If you are suffering from a sleep disorder, do not self-treat. Consult with your physician. Treatment is available.

Read more here

Understanding jet lag may help develop drugs to help with time zone changes

A study using jet lagged mice helps researchers determine what makes people slow to adjust to jet lag and may help develop medication to make the transition easier.

New research in mice reveals why the body is so slow to recover from jet lag and identifies a target for the development of drugs that could help us to adjust faster to changes in time zone.

With funding from the Wellcome Trust and F. Hoffmann La Roche, researchers at the University of Oxford, University of Notre Dame and F. Hoffmann La Roche have identified a mechanism that limits the ability of the body clock to adjust to changes in patterns of light and dark. And the team show that if you block the activity of this gene in mice, they recover faster from disturbances in their daily light/dark cycle that were designed to simulate jet-lag.

Nearly all life on Earth has an internal circadian body clock that keeps us ticking on a 24-hour cycle, synchronising a variety of bodily functions such as sleeping and eating with the cycle of light and dark in a solar day. When we travel to a different time zone our body clock eventually adjusts to the local time. However this can take up to one day for every hour the clock is shifted, resulting in several days of fatigue and discombobulation.

In mammals, the circadian clock is controlled by an area of the brain called the suprachiasmatic nuclei (SCN) which pulls every cell in the body into the same biological rhythm. It receives information from a specialised system in the eyes, separate from the mechanisms we use to 'see', which senses the time of day by detecting environmental light, synchronising the clock to local time. Until now, little was known about the molecular mechanisms of how light affects activity in the SCN to 'tune' the clock and why it takes so long to adjust when the light cycle changes.

To investigate this, the Oxford University team led by Dr Stuart Peirson and Professor Russell Foster, used mice to examine the patterns of gene expression in the SCN following a pulse of light during the hours of darkness. They identified around 100 genes that were switched on in response to light, revealing a sequence of events that act to retune the circadian clock. Amongst these, they identified one molecule, SIK1, that terminates this response, acting as a brake to limit the effects of light on the clock. When they blocked the activity of SIK1, the mice adjusted faster to changes in light cycle.

Dr Peirson explains: "We've identified a system that actively prevents the body clock from re-adjusting. If you think about, it makes sense to have a buffering mechanism in place to provide some stability to the clock. The clock needs to be sure that it is getting a reliable signal, and if the signal occurs at the same time over several days it probably has biological relevance. But it is this same buffering mechanism that slows down our ability to adjust to a new time zone and causes jet lag."

Disruptions in the circadian system have been linked to chronic diseases including cancer, diabetes, and heart disease, as well as weakened immunity to infections and impaired cognition. More recently, researchers are uncovering that circadian disturbances are a common feature of several mental illnesses, including schizophrenia and bipolar disorder.

Russell Foster, Director of the recently established Oxford University Sleep and Circadian Neuroscience Institute supported by the Wellcome Trust, said: "We're still several years away from a cure for jet-lag but understanding the mechanisms that generate and regulate our circadian clock gives us targets to develop drugs to help bring our bodies in tune with the solar cycle.Such drugs could potentially have broader therapeutic value for people with mental health issues."

Read more here