Sleep wake cycle

Wake Up To The Importance Of Sleep in Shreveport

Circadian Rhythm Sleep Disorders occur when one's schedule requires one to work when one's body wants to sleep and  try to sleep when one's body expects to be awake. In other words the biological and socio-occupational schedules are out of sync with each other.


The biologic clock or "circadian oscillator" controls the “circadian rhythms” in the body. The word “circadian” means occurring over a cycle of about 24 hours. The biologic clock tells your body when it is time to sleep at night and when it is time to be wake up for the day. The biological clock is “set by when you get light exposure.

Shift Work Sleep Disorder

Shift work sleep disorder is a 


There are several types of shift work schedules. These include the following:


  • Night shifts
  • Early-morning shifts
  • Rotating shifts


This sleep problem causes you to have trouble sleeping or to be severely tired. It is most often reported due to the night and early-morning shifts. These workers typically sleep one to four hours less than average. They also feel that the quality of their sleep is very poor. They do not feel refreshed when they wake up. This can hinder their performance at work. It can also make them less alert. This can put them at risk of an injury on the job.


The condition usually lasts as long as you keep a shift work schedule. Once you begin sleeping at a normal time again, the problems tend to go away. In some people, the sleep problems may continue even after the shift work schedule has ended. The length and severity of the problem varies from person to person. Some people are able to adjust better than others. There are also many different types of work schedules. Some people may only work an overnight shift to cover for a co-worker. Their sleep problem would be very brief. Others may work a regular night shift. Their problem would be ongoing. Many shift workers also work more hours each week than the average person. This can add fatigue to their sleep problems.


Many early-morning work shifts start between 4 a.m. and 7 a.m. These shifts may cause you to have trouble falling asleep or waking up. Those who work a regular evening shift may also have a hard time falling asleep.


Those who work night shifts are likely to become very tired on the job. They may feel a strong urge to take a nap. They also may not think clearly because of a reduced level of alertness. They are more likely to make mistakes.


They tend to sleep during normal nighttime hours on weekends or days off. This makes it even harder for their bodies to adjust to the unusual work hours.


This disorder can also affect you away from the job. You may need to use major portions of your free time to catch up on sleep. This can have a negative impact on your social and family life. You may also be more irritable. This can hurt your relationships with others. The disorder also increases the risk of drowsy driving. This can lead to an auto accident as you drive home from work. The disorder may also make stomach or heart disorders worse. Using drugs or alcohol to try to improve sleep can lead to substance abuse.

  • Who gets it?

    Sleep problems from shift work affect male and female workers of all age groups. Those who have unusual work hours are most likely to have it. Estimates are that 2% to 5% of the general population is affected. This estimate does not include people who work early-morning shifts.


    Some people feel that they function better at night. They go to bed very late at night on a regular basis. They may have delayed sleep phase disorder. These people may choose to work a night shift. They prefer to work during the late hours when they feel that they are more alert.


  • How do I know if I have it?

    1. Do you have trouble sleeping or are you severely tired?


    2. Is this problem due to a schedule that requires you to work when you would normally sleep?


    3. Have you had this work-related sleep problem for at least one month?


    4. Does this problem hurt your social, family, or work life?


    If your answer to each of these questions is yes, then you might have shift work disorder.


    It is also important to know if there is something else that is causing your sleep problems. They may be a result of one of the following:

    • Another sleep disorder
    • A medical condition
    • Medication use
    • A mental health disorder
    • * Substance abuse

  • Do I need to see a sleep specialist?

    You may have to keep unusual work hours for a long period of time. In this case, you may want to visit a sleep specialist. He or she can provide you with methods to help your body adjust and to improve your sleep.

  • What will the doctor need to know?

    You should complete a sleep diary for two weeks. This will give the doctor clues as to what might be causing your problems. You can also rate your sleep with the Epworth Sleepiness Scale. This will help show how your sleep is affecting your daily life. The doctor will need to know your complete medical history. Be sure to inform him or her of any past or present drug and medication use.

  • Will I need to take any tests?

    Normally, a record of your sleep patterns and your work schedule is enough information for the doctor. He or she may want to use additional tests if other sleep disorders are suspected to be causing your problems. One or both of the following sleep studies might be considered:


    1. Overnight Sleep Study


    Also called a polysomnogram, this study charts your brain waves, heart beat, and breathing as you sleep. It also records how your arms and legs move.


    2. Multiple Sleep Latency Test (MSLT)


    This is a daytime nap study that records brain waves during at least four naps. The MSLT measures how fast you fall asleep during the day. It also shows what kind of sleep you have when you take a nap.


    Your doctor may ask that you take a test to screen for drugs before you have the MSLT. There are a number of drugs that can affect the results of the sleep study. The drug screen will help the doctor to know what the MSLT really says about your sleep problem.

  • How is it treated?

    Many employers have plans to help their shift workers stay better rested. The goal is to lessen the effects of shift work on the workers’ body clocks. This keeps them healthier overall, as well as safer on the job. Some of the techniques used by employers include the following:


    • Reducing the number of times a worker changes shifts
    • Changing shifts forward in time instead of backward
    • Giving the workers regular rest periods
    • Offering employees the option of exercise breaks
    • Using bright light to imitate sunlight

Delayed Sleep Phase

Delayed sleep phase disorder (DSP) is a circadian rhythm disorder. It consists of a typical sleep pattern that is "delayed" by two or more hours. This delay occurs when one’s internal sleep clock (circadian rhythm) is shifted later at night and later in the morning. Once sleep occurs, the sleep is generally normal. But the delay leads to a pattern of sleep that is later than what is desired or what is considered socially acceptable. This pattern can be a problem when it interferes with work or social demands.


A person with DSP is likely to prefer late bedtimes and late wake-up times. When left to his or her own schedule, a person with DSP is likely to have a normal amount and quality of sleep. It simply occurs at a delayed time. One sign of this disorder is difficulty falling asleep until late at night. Another sign is having a hard time getting out of bed in the morning for work or school. These signs can make DSP look like insomnia. Daytime functioning can be severely impaired by DSP. It can lead to excessive sleepiness and fatigue. When able to sleep on their own schedules, people with DSP often stay up until they get tired and then sleep until they awaken late in the morning. In this case, they tend to have no complaint of difficulty falling to sleep or feeling poorly during the day.

  • Who gets it?

    The exact rate of DSP is unknown in the general population. It is much more common in teens and young adults. From 7% to 16% of them may have it. DSP is likely to be found in 10% of people with a complaint of chronic insomnia. People who tend to be "evening types" or "night owls" are likely to develop DSP.


    There is likely to be some genetic component. Some environmental factors may also be involved. A lack of exposure to morning sunlight may make it worse. Too much exposure to bright evening sunlight may also increase symptoms of DSP. A family history of DSP is common in about 40% of people with the disorder.


    It is easy to confuse DSP with normal variations of sleep and other types of insomnia. Consulting with a sleep specialist is your best bet to help clarify current sleep problems. He or she will also be able to help you develop a plan to correct these problems. A specialist can assess the factors that cause and make this problem worse. These include both social and behavioral factors.


  • What will the doctor need to know?

    The sleep doctor will do a thorough physical exam. He or she will also discuss with you the history of these sleep problems. It would be helpful to keep a sleep diary prior to seeing a sleep doctor. Bring this information with you to the appointment. A sleep diary is a systematic way to track your sleep pattern. You record the time you get into bed, the time required to fall asleep, and the time you wake up in the morning. Sleep diaries often show a regular pattern of difficulty falling to sleep. They often show few or no awakenings once asleep. They also tend to show a sleep duration that is reduced during the work week and lengthy on the weekend.


  • Will I need to take any tests?

    An overnight sleep study is not normally needed for someone who suffers from DSP. Your doctor may have you do an overnight sleep study if your problem is severely disturbing your sleep. This study is called a polysomnogram. It charts your brain waves, heart rate, and breathing as you sleep. It also records how your arms and legs move. This study will help determine if there are any objective sleep disorders related to your sleep problem.

  • How is it treated?

    The most accepted treatment for DSP is what is called chronotherapy. This is a method of behavioral treatment. Your bedtime is delayed by about three hours per day for five or six consecutive days. Once the desired bedtime is reached the schedule is frozen. This schedule needs to be maintained rigidly at this point.


    Bright light therapy is another proven technique for changing one’s internal circadian rhythms. But its specific use for DSP has not been well validated. In theory, exposure to bright light should occur shortly after waking up at the desired time in the morning. Then bright outdoor light in the evening hours should be avoided.


    • Reducing the number of times a worker changes shifts
    • Changing shifts forward in time instead of backward
    • Giving the workers regular rest periods
    • Offering employees the option of exercise breaks
    • Using bright light to imitate sunlight

Advanced Sleep Phase

Advanced sleep phase disorder (ASP) is one of several circadian rhythm sleep disorders. These disorders occur in people who sleep at times that seem to be out of order with “normal” sleep times. People with ASP have an “early bird” circadian clock. They fall asleep several hours before a normal bedtime. As a result, they also wake up hours earlier than most people wake in the morning.


People with ASP feel sleepy in the late afternoon. Bedtime tends to occur between 6 p.m. and 9 p.m. Since bedtime is early, they also wake up early. They tend to wake up between 2 a.m. and 5 a.m. While the timing of sleep is early, sleep itself is normal.


All of the circadian rhythms related to sleep also occur at early times. This includes an earlier release of melatonin and other hormones. The body temperature curve is also moved earlier. This has been used as a marker to detect this disorder.


Some people with ASP are able to follow this early schedule. But problems often occur when social plans take place during the late afternoon or evening. This makes them struggle to stay awake. They may appear very sleepy to others during these evening hours. Missing a few hours of evening sleep over time can cause chronic sleep deprivation. This results in true sleepiness. Even when deprived of sleep, people with ASP still tend to wake up early.


People with ASP may mistake their problem for something else. They may think that waking up too early is a sign of either insomnia or depression. They may worry about being awake so early. It is hard for them to be awake at a time when others are asleep. They may develop a secondary form of insomnia as a result of their worries.


People with ASP may adjust their lifestyles or jobs around their natural “early bird” clock. For example, an “early bird” clock would be ideal for working the early shift. This includes jobs such as a baker or surgeon. Other people with ASP do things to worsen their condition. They try to realign their early clock to match the schedules of others. For example, they may drink too much coffee or take stimulants to stay awake at night. They may also try to stay asleep during the morning hours. To do this, they may drink alcohol or take sleeping pills. These choices will only make their sleep worse.


  • Who gets it?

    Advanced sleep phase disorder is not very common. It is estimated to occur in only 1% of middle-age adults. It is more common in older adults and seniors. Men and women are affected at an equal rate. A genetic link has been shown in some families. This should be considered in younger patients. ASP may be caused, increased, or maintained by environmental factors. It can also result from outside social or work pressures.

  • How do I know if I have it?

    1. Do you fall asleep during the late afternoon or early evening AND wake up too early while everyone else is still sleeping?


    2. Do you feel very sleepy in the late afternoon AND very alert between 2 a.m. and 5 a.m.?


    3. Do you have a natural “early bird” clock every night?


    If your answer to these questions is yes, then you might have advanced sleep phase disorder.


    It is also important to know if there is something else that is causing your sleep problems. They may be a result of one of the following:

    • Another sleep disorder
    • A medical condition
    • Medication use
    • A mental health disorder
    • Substance abuse

  • Do I need to see a sleep specialist?

    ASP is a sleep disorder that may or may not cause problems. You may be able to adapt your lifestyle to the early schedule. If so, then you should not need treatment. But this early sleep time is often out of line with the schedules of others. You may not be able to adapt your job or social life to your “early bird” clock. This may lead you to try things that will make your sleep problem worse. This “early to bed, early to rise” schedule may cause severe sleepiness. It may also lead to problems with family, friends, or work. If this is the case, then you should seek a doctor’s advice.

  • What will the doctor need to know?

    The doctor will ask you about your medical history. Your family history may also provide important details. The doctor should do a full exam. You will be asked to complete a sleep diary over several weeks. This will show the times when you normally go to sleep and wake up. You may be asked to rate your sleep with the Epworth Sleepiness Scale. This will help show how your sleep is affecting your daily life. Be sure to inform the doctor of any past or present drug, alcohol, and medication use. Also tell the doctor if you have ever had any other sleep disorder.

  • Will I need to take any tests?

    Detecting ASP can be done through an office visit with details from your sleep diary. An overnight sleep study should not be needed. A sleep study may be used if you are at risk for other sleep disorders. The sleep study is called a polysomnogram. It charts your brain waves, heart beat, and breathing as you sleep. It also records how your arms and legs move. This shows if there are other sleep disorders that are causing or increasing your sleep problems. Examples of these disorders include sleep apnea and periodic limb movement disorder. Since you go to sleep and wake up early, the sleep study should be performed during the early sleep times. If you do not have another sleep disorder, then the sleep study should show your sleep to be normal.


    You may be asked to use an actigraph at home. This is a device that you wear on your wrist. It records your sleep activity over a period of one to two weeks. Other methods of testing could be used. This might include ongoing monitoring of your body temperature. Your melatonin levels may also be measured by testing your saliva. But these tests are mostly used for research.

  • How is it treated?

    ASP may or may not need to be treated. People with ASP often adapt their lifestyles to an early schedule. If they are able to do this, then they should not have any sleep problems. But problems will occur if they try to follow a later schedule.


    Doctors first try to help patients adjust to their “early bird” clocks. This is done through education and behavioral counseling. For example, people with ASP should not make plans to do things late at night. They also should not work the late afternoon or evening shifts. They should not use caffeine or stimulants in the evening. This will only worsen their sleep. Waking up early should be seen as something positive. Much can be done during the time when others are asleep. They should not use alcohol or drugs to stay asleep during early-morning hours.


    Other treatment options include the following:

    • Advancing the bedtime slowly over time
    • Using bright light therapy during the early evening
    • Taking melatonin in the morning

Bright Light Therapy

Light therapy is a treatment used for people who suffer from circadian rhythm sleep disorders. Your body has an internal clock that tells it when it is time to be asleep and when it is time to be awake.


This clock is located in the brain just above an area where the nerves travel to the eyes. This area is called the SCN. Your clock controls the “circadian rhythms” in your body. These rhythms include body temperature, alertness and the daily cycle of many hormones.


The word “circadian” means to occur in a cycle of about 24 hours. Circadian rhythms make you feel sleepy or alert at regular times every day. Some people have a circadian rhythm sleep disorder. This causes their natural sleep time to overlap with regular awake activities such as work or school.


Among other factors, your clock is “set” by your exposure to bright light such as sunlight. Exposure to bright light or “light therapy” is one method used to treat people with a circadian rhythm sleep disorder.


The goal for treating patients who have circadian rhythm problems is to combine a healthy sleep pattern with an internal clock that is set at the right time. This will allow them to enjoy the benefits of good sleep.


Light therapy can help someone “re-set” a clock that is off. Regular sleep patterns help to keep the clock set at the new time. Light therapy is only part of a treatment plan that should be guided by a doctor who is familiar with sleep disorders.


Light therapy is used to expose your eyes to intense but safe amounts of light for a specific and regular length of time. In many places, sunlight is not available at the proper time to be used as treatment.

Artificial light may be used to affect the body clock in the same way that sunlight does. New advances continue to be made in this field. Currently, products that are used for light therapy fit into four basic groups:

  • Light Box

    This is the most common tool that is used in light therapy. The box houses several tubes that produce extremely bright light. It sits on top of a table or desk and plugs into the wall.


    During a treatment session, you have to keep within a certain distance of the box. Usually, you will be about 18 to 24 inches away from it. It does not require you to look directly into the light. Instead, you simply face in the direction of the box.


    You are able to do other activities during the session. Ideally, you would work on papers or read something that is in the area being lit up. This will allow the light to be received by your eyes. Your body takes in this information and uses it to regulate the rhythms that control when you sleep and when you wake.


    Earlier models of light boxes put out 2,500 to 5,000 lux of light. Lux is a measure of how much light falls on your eyes. These sessions could take two or three hours. Now, many boxes produce 10,000 lux of light. This allows sessions to take as little as 15 to 30 minutes.


    More than one session may be needed each day. It depends upon your body, your need, and the strength of light being used. The key is to use the light at the right time of day and for the right amount of time. This is based upon the sleep disorder you want to correct.


    New models are also safer, protecting you from harmful UV rays. Some models are now focusing on a specific bandwidth of light. Light boxes can be purchased in a variety of makes and models. Some are now being made much smaller so they are easier to take with you. General prices range from $200 - $500 per light box.

  • Desk Lamp

    This serves the same purpose as a light box, but it is made to look like a normal lamp. It blends in better when used in an office setting.

  • Light Visor

    This is a light source that is worn on your head and hangs over your eyes. It looks much like a tennis visor. It is made so that you can move around during sessions. The strength of visor lights also varies from 3,000 to 10,000 lux.

  • Dawn Simulator

    These lights gradually make a dark room brighter over a set period of time. This is meant to mimic the sunrise. Some people may find that this helps them wake up in the morning. Models may also slowly dim to copy a sunset.

Who gets it?

Bright light therapy is used for people who suffer from circadian rhythm disorders. The time of day when the light is used will depend upon the disorder it is meant to correct. These disorders include the following:



1. Delayed sleep phase disorder


This causes people to fall asleep much later at night than is normal. As a result, they also wake up later in the morning. This sleep pattern can interfere with their schedule of activities for the day. To correct delayed sleep phase, light treatment takes place during the early morning hours.


2. Advanced sleep phase disorder


This causes people to fall asleep much earlier at night than is normal. They also wake up earlier in the morning. To correct it, light treatment takes place early at night.


3. Free-running or Non-24-hour sleep-wake rhythm


People with this disorder fall asleep at a different time each day. For example, you may fall asleep at 10 p.m. one day, Midnight the next day, 2 a.m. the next, etc. This most often occurs in people who are blind. Light therapy may help blind people, even if they can't perceive visible light. Studies show that light treatment may be useful in the early morning hours.


4. Jet lag


Jet lag causes people to have problems with sleep when they have crossed many time zones on a flight. Light therapy in the morning may help when traveling east. For travel to the west, bright light in the evening may help reduce jet lag.


5. Shift Work


This sleep disorder occurs due to a work schedule, such as night shift, that takes place during the time when most people are sleeping. This schedule requires you to work when your body wants to sleep. Then you have to try to sleep when your body expects to be awake. Correcting it can be a hard problem to solve. Changing work schedules, days off, and social activities can alter your exposure to light from day to day. Frequent changes in your sleep times make it hard to re-set your internal clock. In general, using light treatment in the evening should help someone who regularly works nights. In this case, you would also want to avoid daylight when you come off work and go to bed. Dark sunglasses or special goggles can help.


6. Seasonal affective disorder (SAD)


SAD is a mood disorder that can cause people to feel sad and lack energy during the dark months of winter. A similar and milder version is often called the “Winter Blues.” In severe forms, sadness may be caused by depression. Light therapy is thought to be useful as one of the treatments for seasonal mood disorders and depression. Depression is also treated with medications. You should consult your doctor if you are having serious problems with sadness.


Possible side effects?


Light therapy has a good record of safety. It does not seem to produce any major side effects. Light therapy should always be used within the proper limits for intensity and time. Minor side effects may include the following:


  • Eye irritation and dryness
  • Headache
  • Nausea
  • Dryness of skin


To reduce these side effects, begin the light therapy very slowly. Give your body time to get used to it. The use of a humidifier can also help with irritations caused by dryness. Talk to your doctor or a sleep specialist before beginning use.