Pathophysiology of Sleep Apnea

  • sleep apnea cycleSleep Onset
  • Airway Collapse
  • Apnea
  • Hypoxia and Hypercapnia
  • Increased Ventilation Effort
  • Arousal
  • Airway Open
  • Hyperventilate
  • Sleep Onset and repeat cycle


Importance of Sleep from the National Institute of Health

Physical Health: Sleep is involved in healing and repairs of your heart and blood vessels. Ongoing sleep insufficiency is linked to and increased risk of heart disease, kidney disease, diabetes and stroke. Sleep affects hormone production and how your immune system responds.

Mental and Emotional Health: Sleep allows the brain to form new pathways to improve memory and learning. Sleep deficiency alters activity in some parts of the brain causing issues with decision making, problem solving and controlling emotions.

Daytime Performance and Safety: Daytime fatigue can lead to a decrease in productivity and increase in mistakes. It is estimated that driver sleepiness is a factor in about 100,000 car accidents every year, resulting in about 1,5000 deaths.

Sleep Problems and Sleep Apnea Pasadena Texas


Sleep Stages

None-Rem Stages

Stage 1 (N1): Between being awake and falling asleep. Also known as somnolence or drowsy sleep in which muscles are still quite active and sleep is easily disrupted. Represents around 5% of total sleep time.

Stage 2 (N2): First unequivocal stage of sleep during which muscle activity decreases and conscious awareness of the outside world begins to fade completely. Represents around 45% to 50% of total sleep time.

Stage 3 (N3): Also known as delta sleep. Least responsive to outside environment: considered the deepest sleep stage where the brain activity, breathing rate, and blood pressure are all at their lowest levels. Represents around 15%-20% of total sleep time.

Rapid Eye Movement (REM)

Occurs in cycles of about 90-120 minutes throughout the night

Accounts for up to 20-25% of total sleep time in adults

“Dreaming Sleep”

Characterized by elevated EG activities, similar to that of an awake person, as well as rapid eye movement

Skeletal muscles are paralyzed during REM as a built-in measure to protect us from self-damage which could occur while physically acting out these vivid dreams

Duration of Sleep Stages

  • Stage 1 NREM 5%
  • Stage 2 NREM 45%
  • Stage 3 NREM 25%
  • REM 25%


Difficulty falling asleep or staying asleep, even when a person has the chance to do so.

Patients with insomnia can feel frustrated with their sleep and usually experience on or more of the following symptoms: fatigue, low energy, difficulty concentrating, mood disturbances, and decreased performance at work or at school.

Two most common symptoms are 1) Waking up feeling unrefreshed 2) Waking up often during the night

Sleep Apnea

Apnea: “Asphyxia”, transient cessation of respiratory whether normal of abnormal. Apnea is Greek for “want of breath”

Sleep Apnea: “Asphyxia during sleep”. Breathing repeatedly stops during sleep.

  1. Obstructive Sleep Apnea (OSA): Apnea that is caused by a mechanical obstruction of the airway. It is caused by partial of complete blockage of the airway during sleep when the muscles relax allowing the tongue and/or fatty tissues of the throat to fall back into the airway and block flow
  2. Central Sleep Apnea (CSA): Breathing stoppage caused by neurological condition. Occurs when the brain temporarily fails to signal the muscles responsible for controlling breathing.
  3. Mixed Sleep Apnea: A combination of both OSA and CSA


Apnea Pasadena Texas

OSA Diagnostic Index and Severity

OSA consists of two types of events

APNEA – 100% flow limitation for 10 seconds or greater

Hypopnea – partial airflow blockage accompanied by a decrease in oxygen saturation of at least 4% or greater

Apnea Hypopnea Index (AHI) = the (total number of apneas + hypopneas) / # of hours of sleep

AHI 5 -15 = MILD



sleep apnea complications


Severe sleep apnea raises the risk of dying early by 46%.

Researchers studied 6,400 men and women for eight years. Those who started with major sleep apnea were 46% more likely to die from any causes, regardless of age, sex, race, weight or smoking. This report was published in the Public Library of Science Journal.

Men aged 40 to 70 with severe sleep disordered breathing were twice as likely to die from any cause as health men of the same age.