Hypercapnia - A raised level of carbon dioxide in the blood. This is the gas normally breathed out which will rise if breathing is inadequate. Usually measured by taking an arterial blood sample.
Hypersomnolence - Technical expression for excessive sleepiness.
Hypnogram - The final print out of the all night sleep stages.
Hypopnoea - A period of under-breathing: conventionally for more than 10 seconds.
Insomnia - Being awake when you want to be asleep. Often thought of as a problem, but may not be. Common if people try to spend too long in bed.
Pharynx - Essentially the throat area between the voice box and the back of the nose behind the tongue. A floppy muscular tube.
Sleep Stages - Sleep is conventionally divided into five stages. Four of these are called non-REM sleep, the other is REM (or Rapid-Eye-Movement) sleep. REM sleep is when we dream, and the brain is virtually awake. Non-REM sleep is graded 1 to 4 and represents increasing depths of sleep. This is the sleep required to refresh, with the two deeper stages 3 and 4 called slow wave sleep.
Snoring - The noise resulting from vibration in the upper airway; anywhere from the back of the nose down to the voice box. Often involves the palate.
Uvulopalatopharyngoplasty - The operation that cuts away part of the soft palate and side walls of the pharynx (or throat) in an attempt to reduce snoring volumes. Not very effective and extremely painful.