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SLEEP ARCHITECTURE

This describes the stages and cycles of sleep. Non-rapid eye movement (NREM) composes 75% of the sleep cycle, whereas, rapid eye movement (REM) represents the remaining 25% of the sleep cycle.

1. Non-Rapid Eye Movement (NREM)
  • Transitional Phase- Between wakefulness and sleep. This lasts for 1 to 7 minutes and is 5% of the total sleep time.
  • Light Sleep Phase- This is 50% of the total sleep time.
  • Slow Wave Phase (Delta Phase)- A deeper and more relaxed sleep associated with 20% of the total sleep time.

2. Rapid Eye Movement (REM)

This a period of deep, refreshing sleep. Eyes move side to side and the skeletal muscles are nearly paralysed which results in a loss of muscle tone in the upper airway. This represents 25% of the total sleep time and is the stage where dreaming occurs.


EXCESSIVE DAYTIME SLEEPINESS (EDS)

People who suffer from obstructive sleep apnea have a fragmented sleep architecture which causes them to spend an excessive amount of time in the lighter stages of sleep at the expense of the Delta Phase and REM stage. This causes them to have excessive daytime sleepiness due to their lack of sleep at night.

The range of total sleep time in normal people is 4 to 10 hours. A predictable temporal pattern of sleep occurs through the night with NREM and REM sleep, alternating in recurrent 90 to 110 minute cycles. A normal sleep pattern has 4 - 5 cycles per night, Sleep profiles change with time and age. People with obstructive sleep apnea have a reduction in REM deep sleep and total sleep time along with repeated nighttime awakenings.


SLEEP ARCHITECTURE STUDY TECHNIQUE


The technique of polysomnography is used to study sleep architecture. A polygraph, polysomnograph (PSG), records multiple physiological variables that affect sleep. Parameters measured by the PSG include: an electroencephalogram (EEG), which measures brain activity; an electro-oculogram (EOG), which monitors eye movement; and an electromyogram (EMG), which measures muscle activity, and records respiration, heart rate and oxygen saturation.

Every patient should have an attended PSG at the onset of treatment. This provides the health care practitioner with a complete report on the patient's sleep architecture, lab-based and scored by a sleep technician. PSGs are generally required for insurance reimbursement. Only a physician, trained in sleep medicine, can diagnose the types of sleep apnea.


TYPES OF SLEEP APNEA

1. Obstructive Sleep Apnea (OSA)

OSA is the most common type of sleep apnea (75-80%). Obstructive sleep apnea is caused by an obstruction in the airway, which actually stops the air flow in the nose and mouth. Throat and abdominal breathing continue normally. OSA is commonly accompanied by snoring and causes the sleeper to wake up, gasping or snorting, and then go back to sleep again.

2. Central Sleep Apnea (CSA)

CSA is a much less common type than obstructive sleep apnea. CSA is due to a brain signal problem; the brain signal that instructs the body to breathe is delayed. With CSA, oral breathing, throat, and abdominal breathing all cease at the same time. The periods of breathing interruption may last a few seconds, and breathing may be too shallow to provide oxygen to the blood and tissues. Central sleep apnea is due to heart failure.

3. Mixed Sleep Apnea (MSA)

When individuals experience a combination of the two other types of sleep apnea, obstructive sleep apnea and central sleep apnea, they have mixed sleep apnea.


SIGNS AND SYMPTOMS OF SLEEP APNEA

  1. Frequent cessation of breathing (apnea) during sleep. Your sleep partner may notice repeated silences.
  2. Choking, gasping, or gagging during sleep to get air into the lungs.
  3. Loud snoring.
  4. Waking up sweating during the night.
  5. Feeling unrefreshed in the morning after a night's sleep.
  6. Headaches upon awaking.
  7. Daytime sleepiness, including falling asleep at inappropriate times, such as during driving, or at work.
  8. Lethargy.
  9. Rapid weight gain.
  10. Memory loss and learning difficulties.
  11. Short attention span.
  12. Poor judgment.
  13. Depression.
  14. Personality changes.

WHAT TREATMENTS CAN CURE SLEEP APNEA?

Once a diagnosis has been made by a sleep physician, the treatment of central and mixed sleep apnea falls in the realm of the physician. Obstructive sleep apnea, once diagnosed by a sleep physician may be treated by a qualified dentist.

Physical devices or mechanical therapies are effective for many cases of sleep apnea. These solutions fall into the following categories: oxygen administration, continuous positive airway pressure (CPAP), surgery, and oral appliances.

Behavioral therapies are an important part of the treatment for sleep apnea, especially in cases where a physician has identified a specific cause of the restricted airway. The following are the most effective home remedies one can try: lose weight; eliminate the use of alcohol, tobacco, and sedatives; sleep on your side; and regularize your sleeping hours.

It is absolutely essential that dentists get an overnight sleep study done and diagnosed by a sleep physician prior to the fabrication of an oral appliance. A proper medical evaluation must precede appliance therapy. The American Academy of Sleep Medicine (Medical Division) and the Academy of Dental Sleep Medicine (Dental Division), both agree that oral appliances are indicated for patients with mild to moderate sleep apnea. Oral appliances are also indicated in severe cases of obstructive sleep apnea where patients cannot tolerate CPAP treatment, and in patients who refused any of the proposed surgical options.

It is important that the dentist confirm that his oral appliance therapy was successful in not only reducing the snoring but also the obstructive sleep apnea. This can be accomplished by a follow up sleep study. Clinicians must be careful to avoid creating a silent apneic, which can be extremely detrimental to the patient's health. The Watch Pat-100 overnight home sleep study is therefore vital to confirm that the patient's RDI and AHI have been significantly reduced, proving that the oral appliance therapy has been successful.

APNEA-HYPOPNEA INDEX (AHI) and RESPIRATORY DISTURBANCE INDEX (RDI) VALUES PER HOUR
AHI RDI
Mild OSA
Moderate OSA
Severe OSA
5-15
15-30
30 plus
5-20
20-30
40 plus
 


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