Glossary
Apnea
Cessation of breathing during sleep.
Apnea Index
Number of apneas per hour of sleep.
Arousals
Brief awakenings that are typically more than
3 seconds and less than 15 seconds in duration.
Cheyne-Stokes Respiration (Breathing)
A very specific form of central sleep apnea, mostly
due to cardiac problems or brain problems.
CSA (Central Sleep Apnea)
Cessation of breathing during sleep due to lack
of respiratory effort.
Desaturation
Decrease in oxygen saturation in blood.
DI (Desaturation Index)
Number of times that oxygen saturation decreases
by 4% and comes back to normal level per hour of sleep.
Hypopnea
Shallow breathing during sleep that is significant
enough to cause a drop in blood oxygen or cause
arousals of the brain.
Hypopnea Index
Number of hypopneas per hour of sleep.
Hypoventilation
Shallow breathing to a degree that carbon dioxide
accumulates in the blood.
Insomnia, Sleep-Maintenance
Difficulty falling back asleep after nocturnal awakening.
Insomnia, Sleep-onset
Difficulty initiating sleep.
Nocturia
Urination after falling asleep (going to the bathroom).
Obstructive Sleep Apnea
Cessation of breathing during sleep due to closure
of the throat.
OHS (Obesity Hypoventilation Syndrome)
This is a condition in which severely obese people fail
to breathe quick enough or deeply enough, which
results in low blood oxygen levels and high blood
carbon dioxide levels.
OSA (Obstructive Sleep Apnea)
This is closure of an airway passage that occurs
only during sleep.
Oxygen Desaturation
Decrease in blood oxygen saturation.
PLM (Periodic Leg Movement)
Leg twitches that occur during sleep and the
person is unaware of them. This is a test finding.
PLMD (Periodic Leg Movements Disorder)
Leg twitches that occur during sleep, and the person
is unaware of them. This is a clinical diagnosis.
RDI (Respiratory Disturbance Index)
Apnea Index + Hypopnea + RERA index
RERA (Respiratory-Related Arousals)
Shallow breathing that does not cause an oxgenation
problem, but cause brain arousals.
RLS (Restless Legs Syndrome)
This is a condition that is characterized by an irresistible
urge to move one's body to stop uncomfortable or
odd sensations.