Sleep Disorders Glossary H

Sleep Disorders Glossary - H

Habitual Snorers

Habitual snorers are that individuals who snore almost every night.

Heart Rate/ Beats Per Minute (bpm)

Heart Rate is a term used to describe the frequency of the cardiac cycle. It is considered one of the four vital signs. Usually it is calculated as the number of contractions (heart beats) of the heart in one minute and expressed as "beats per minute" (bpm).

Heart rate is continuously monitored in both diagnostic sleep studies and CPAP titration studies.

Hertz (Hz)

Hertz (Hz) is the unit of frequency measuring cycles per second (cps). A measurement used in describing sleep EEG brain waves.


Histogram is a bar graph of a frequency distribution in which the widths of the bars are proportional to the classes into which the variable has been divided and the heights of the bars are proportional to the class frequencies.


Homeostatic/Homeostasis is the balanced state of the living body, in spite of variations in the environment.

Homeostatic Regulation Of Sleep

Homeostatic regulation of sleep refers to the neurobiological signals arbitrating the pressure or urge to sleep.


Humidification is the adding moisture to the airflow as an addition to Continuous Positive Airway Pressure therapy, while treating obstructive sleep apnea (OSA). To prevent the upper airway from drying out humidification is added to the CPAP device by diverting the airflow over a cool or heated water reservoir (humidifier).

Hyoid advancement

Hyoid advancement is a surgical treatment for enlarging the air space behind the tongue. In Hyoid advancement, the hyoid bone is moved forward and either attached to the Adam's apple or to the jawbone and thereby the airspace behind the tongue is enlarged.

Hyoid bone

Hyoid bone is a U-shaped bone at the base of the tongue that supports the muscles of the tongue.

Hyoid Suspension

Hyoid Suspension is a surgical treatment for sleep apnea or snoring by improving the airway behind the base of the tongue. If the hyoid bone containing these muscles is pulled forward in front of the voice box, it can open the airway space behind the tongue.


Hypercapnia is a condition marked by an unusually high concentration of carbon dioxide in the blood .


Hyperirritability is extreme irritability, which is often seen in sleep deprived individuals.


Hypersomnia refers to either excessive sleepiness during the day or extended, overly long periods of nighttime sleep. It may be associated with difficulty in awakening. Other words that are synonymous with hypersomnia are excessive daytime sleepiness (EDS), excessive sleepiness, or somnolence.


Hypersomnolence is excessive daytime sleepiness.


Hypertension is elevated blood pressure resulting from an increase in the amount of blood pumped by the heart or from increased resistance to the flow of blood through the small arterial blood vessels .

Hypnagogic Hallucinations

Hypnagogic Hallucinations is a

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