One of the most common sleep disorders is sleep apnea. Sleep apnea is a condition when the airway temporarily closes during sleep. Severe conditions of sleep apnea can occur 30 or more times an hour. (Sleep disordered breathing is a more inclusive condition including hyopneas and apneas. Hypopneas are 30% decrease in airflow, while apneas are complete cessation of airflow.) Sleep apnea and sleep disordered breathing are screened for with a standard sleep study.
Sleep apnea can affect the patient in two ways:
- Decreasing the oxygen in the blood
- Disrupt sleep architecture.
The temporary closure causes the decrease of oxygen saturation in the blood. The repetitive nature of sleep apnea lowers the average oxygen saturation in the blood for the majority of the evening. Other cardiovascular implications include increased blood pressure.
When the airway reopens it is common for the patient to awaken or have an arousal. Arousals can disrupt sleep architecture. Arousals disrupt restorative sleep inlcuding: slow wave sleep and rapid eye movement sleep (REM). Without restorative sleep, patients experience daytime sleepiness.
Narcolepsy is a condition when the patient falls asleep uncontrollably. This condition can be treated with drug therapy. Narcolepsy is screened for with a fatigue study (MSLT).
Periodic Limb Movement Disorder (PLM)
PLM disorder is a condition when the patient twitches his/her leg(s) at least four times with equal time between each twitch. Some patients can experience long series of PLMs (20 or more). This condition can be treated with drug therapy. PLM disorder is screened for with a standard sleep study.