| R sleep | Rapid Eye Movement (REM) Sleep. One of the stages that make up a sleep cycle. The name comes from the rapid twitching eye movements that occur during this stage. Most dreams occur during R sleep. |
| R/O | Rule out |
| Radiofrequency (RF) | Electromagnetic radiation in the frequency range 3 kilohertz (kHz) to 300 gigahertz (GHz); considered to include microwaves and radio waves. Microwaves occupy the spectral region between 300 GHz and 300 MHz while RF or radio waves include 300 MHz to 3 kHz. |
| Radiofrequency (RF) Procedure | (also known as Somnoplasty) procedure for treating nasal obstruction snoring and in some cases sleep apnea. The procedure uses radiowave energy to reduce snoring and the size of the soft palate. |
| Ramp | The slow rise to full pressure after first turning on the machine available from some manufacturers. |
| RBD | Rem Behavior Disorder |
| RCP | Respiratory Care Practitioner |
| RDI | Respiratory Disturbance Index includes all respiratory events per hour. |
| RDI | Respiratory Disturbance Index |
| REM | Rapid Eye Movement (sleep) |
| REM Density | A function that expresses the frequency of eye movements per unit of time during REM sleep. |
| REM Motor Atonia | The active suppression of activity in the antigravity and voluntary muscles during REM sleep. The muscles are completely flaccid and limp. |
| REM onset | Designation for commencement of a REM period; used also as a shorthand term for a sleep-onset REM period. |
| REM period | REM portion of a NREM-REM cycle; early in the night it may be as short as a half-minute whereas in later cycles longer than an hour. |
| REM rebound or recovery | lengthening and increase in frequency and density of REM periods which results in an increase in REM percent above base line. REM rebound follows REM deprivation once the inhibitory influence is removed. |
| REM sleep | Rapid eye movement sleep - sleep characterized by the active brain waves flitting motions of the eyes and weakness of the muscles; most dreaming occurs in this stage which accounts for about 20% of sleep in adults. |
| REM SLEEP | See sleep stages. |
| REM Sleep Behavior Disorder (RBD) | Disorder in which REM motor atonia is partially or completely absent and the individual acts out the ongoing dream. The behavior in REM behavior disorder is often correlates with the ongoing hallucinatory REM dream episode. |
| REM Sleep Episode | REM sleep portion of a NREM-REM sleep cycle. Early in the first sleep period episodes may be only several minutes in duration. Later REM episodes almost are always longer 20 to 30 minutes up to an hour. |
| REM Sleep Intrusion | Brief interval of REM sleep appearing out of its usual positioning in the NREM-REM sleep cycle. |
| REM Sleep Latency | Interval from sleep onset to the first appearance of REM sleep |
| REM Sleep Onset | Designation for the first epoch of a REM sleep episode |
| REM Sleep Percent | proportion of total sleep time occupied by REM sleep. |
| REM Sleep Rebound | Compensatory increase in REM sleep following experimental reduction. Extension of time in and an increase in frequency and density of REM sleep episodes; usually an increase in REM sleep percent of total sleep time above baseline values. |
| REM-Associated Disorders | Sleep disturbances that occur in REM sleep. |
| REML | REM latency |
| REMS latency | The period of time in the sleep period from sleep onset to the first appearance of stage REMS. |
| RERA | Respiratory effort-related arousal |
| Respiratory Care Practitioner (RCP) | Licensed health care professional specifically trained in cardiopulmonary assessment diagnostics therapy administration and patient education including the identification and treatment of sleep disorders. |
| Respiratory effort | Breathing Effort. It can be measured by the movements of your chest and stomach. OSA involves pauses in breathing that occur even though your body continues making an effort to breathe. In contrast a pause in breathing with no effort to breathe is a sign of CSA. The best method of measuring respiratory effort is respiratory inductance plethysmography. |
| Respiratory inductance plethysmography | Also RIP. The most accurate way to measure respiratory effort. You wear belts around your chest and stomach. These belts contain sensors and wires that carry a small electrical current. Chest or stomach movements produce changes in the current. |
| Restless Legs Syndrome (RLS) | Sleep disorder characterized by a deep creeping or crawling sensation in the legs that tends to occur when an individual is not moving. There is an almost irresistible urge to move the legs; the sensations are relieved by movement. |
| Restlessness (Referring to Quality of Sleep) | Persistent or recurrent body movements arousals and/or brief awakenings in the course of sleep. |
| RF | Radiofrequency |
| RINATEC | Nasal spray that reduces congestion and discharge. Can be used on a long term basis. Prescription only. |
| RIP | Respiratory Inductance Plethysmography |
| RLS | Restless Leg Syndrome |
| RPSGT | Registered polysomnographic technologist. A professional credential that a sleep technologist earns by passing the national certification examination. |
| RSD | Reflex Sympathetic Dystrophy |
| Rx | Prescription |
