|
| Quiet Sleep | A term used for describing NREM sleep in
infants and animals when specific NREM sleep stages 1 to
4 cannot be determined. |
|
| Rapid Eye Movement Sleep (REM Sleep) | See Sleep Stages. |
| Record | The end product of the polysomnograph recording
process. |
| Recording | The process of obtaining a polysomnographic
record. The term is also applied to the end product of the
polysomnograph recording process. |
| REM Density (-Intensity) | A function that expresses the
frequency of eye movements per unit time during sleep stage
REM. |
| REM Sleep Episode | The REM sleep portion of a NREM-
REM sleep cycle; early in the night it may be as short as a
half-minute, whereas in later cycles longer than an hour. See
Sleep Stage REM. |
| REM Sleep Intrusion | REM Sleep Intrusion: A brief interval of REM sleep appearing out of its usual position in the NREM-REM sleep cycle; an interposition of REM sleep in NREM sleep; sometimes appearance of a single, dissociated component of REM sleep (e.g, eye movements, “drop out” of muscle tone) rather than all REM sleep parameters. |
| REM Sleep Latency | The interval from sleep onset to the
first appearance of stage REM sleep in the sleep episode. |
| REM Sleep Onset | The designation for commencement of
a REM sleep episode. Sometimes also used as a shorthand
term for a sleep-onset REM sleep episode. See Sleep Onset;
Sleep-Onset REM Period (SOREMP). |
| REM Sleep Percent | The proportion of total sleep time
constituted by the REM stage of sleep. |
| REM Sleep Rebound (Recovery) | Lengthening and increase
in frequency and density of REM sleep episodes, which result
in an increase in REM sleep percent above baseline. REM
sleep rebound follows REM sleep deprivation once the depriving influence is removed. |
| Respiratory Disturbance Index (RDI) (Apnea-Hypopnea Index) | The number of apneas (obstructive, central, or mixed) plus hypopneas per hour of total sleep time as determined by all-night polysomnography. |
| Restlessness (referring to a quality of sleep) | Persistent or
recurrent body movements, arousals, and brief awakenings
in the course of sleep. |
| Rhythm | An event occurring at an approximately constant
period length. |
|
| Saw-Tooth Waves | A form of theta rhythm that occurs during REM sleep and is characterized by a notched appearance in the waveform. Occurs in bursts lasting up to 10 seconds. |
| Severity Criteria | Criteria for establishing the severity of a
particular sleep disorder according to categories: mild, moderate, or severe. |
| Sleep Architecture | The NREM-REM sleep stage and cycle
infrastructure of sleep understood from the vantage point of
the quantitative relationship of these components to each
other. Often plotted in the form of a histogram. |
| Sleep Cycle | Synonymous with the NREM-REM Sleep Cycle. |
| Sleep Efficiency (or Sleep Efficiency Index) | The proportion
of sleep in the episode potentially filled by sleep, i.e., the
ratio of total sleep time to time in bed. |
| Sleep Episode | An interval of sleep that may be voluntary
or involuntary. In the sleep laboratory, the sleep episode
occurs from the time of “lights out” to the time of “lights
on.” The major sleep episode is usually the longest daily
sleep episode. |
| Sleep Hygiene | The conditions and practices that promote
continuous and effective sleep. These include regularity of
bedtime and arise time; conformity of time spent in bed to
the time necessary for sustained and individually adequate
sleep (i.e., the total sleep time sufficient to avoid sleepiness
when awake); restriction of alcohol and caffeine beverages
prior to bedtime; and employment of exercise, nutrition, and
environmental factors so that they enhance, not disturb, restful sleep. |
| Sleepiness (Somnolence, Drowsiness) | Difficulty in maintaining alert wakefulness so that the person falls asleep if not actively kept aroused. This is not simply a feeling of physical
tiredness or listlessness. When sleepiness occurs in inappropriate circumstances, it is considered excessive sleepiness. |
| Sleep Interruption | Breaks in sleep resulting in arousal and
wakefulness. See Fragmentation; Restlessness. |
| Sleep Latency | The duration of time from “lights out,” or
bedtime, to the onset of sleep. |
| Sleep Log (-Diary) | A daily, written record of a person’s
sleep-wake pattern containing such information as time of
retiring and arising, time in bed, estimated total sleep time,
number and duration of sleep interruptions, quality of sleep,
daytime naps, use of medications or caffeine beverages, nature of waking activities. |
| Sleep-Maintenance DIMS (Insomnia) | A disturbance in
maintaining sleep, once achieved; persistently interrupted
sleep without difficulty falling asleep. Synonymous with sleep
continuity disturbance. |
| Sleep Mentation | The imagery and thinking experienced
during sleep. Sleep mentation usually consists of combinations of images and thoughts during REM sleep. Imagery is vividly expressed in dreams involving all the senses in approximate proportion to their waking representations. Mentation is experienced generally less distinctly in NREM sleep, but it may be quite vivid in stage 2 sleep, especially toward
the end of the sleep episode. Mentation at sleep onset (hypnagogic reverie) can be as vivid as in REM sleep. |
| Sleep Onset | The transition from awake to sleep, normally
to NREM stage 1 sleep but in certain conditions, such as
infancy and narcolepsy, into stage REM sleep. Most polysomnographers accept EEG slowing, reduction, and eventual disappearance of alpha activity, presence of EEG vertex sharp transients, and slow rolling eye movements (the components
of NREM stage 1) as sufficient for sleep onset; others require
appearance of stage 2 patterns. See Sleep Latency; Sleep Stages. |
| Sleep-Onset REM Period (SOREMP) | The beginning of
sleep by entrance directly into stage REM sleep. The onset
of REM sleep occurs within 10 minutes of sleep onset. |
| Sleep Paralysis | Immobility of the body that occurs in the
transition from sleep to wakefulness that is a partial manifestation of REM sleep. |
| Sleep Pattern (24-Hour Sleep-Wake Pattern) | A person's
clock hour schedule of bedtime and arise time as well as nap
behavior; may also include time and duration of sleep interruptions. See Sleep-Wake Cycle; Circadian Rhythm; Sleep Log. |
| Sleep-Related Erections | The natural periodic cycle of penile
erections that occur during sleep, typically associated with
REM sleep. Sleep-related erectile activity can be characterized by four phases: T-up (ascending tumescence), T-max (plateau maximal tumescence), T-down (detumescence), and T-zero (no tumescence). Polysomnographic assessment of sleep-related erections is useful for differentiating organic from nonorganic erectile dysfunction. |
| Sleep Spindle | Spindle-shaped bursts of 11.5-15 Hz waves
lasting 0.5-1.5 seconds. Generally diffuse, but of highest voltage over the central regions of the head. The amplitude is generally less than 50 uV in the adult. One of the identifying
EEG features of NREM stage 2 sleep; may persist into NREM
stages 3 and 4; generally not seen in REM sleep. |
| Sleep Stage Demarcation | The significant polysomnographic characteristics that distinguish the boundaries of the sleepstages. In certain conditions and with drugs, sleep stage demarcations may be blurred or lost, making it difficult to
identify certain stages with certainty or to distinguish the
temporal limits of sleep stage lengths. |
| Sleep Stage Episode | A sleep stage interval that represents
the stage in a NREM-REM sleep cycle; easiest to comprehend
in relation to REM sleep, which is a homogeneous stage, i.e.,
the fourth REM sleep episode is in the fourth sleep cycle
(unless a prior REM episode was skipped). If one interval of
REM sleep is separated from another by more than 20 minutes, they constitute separate REM sleep episodes (and are in separate sleep cycles); a sleep stage episode may be of any
duration. |
| Sleep Stage NREM | The other major sleep state apart from
REM sleep; comprises sleep stages 1-4, which constitute levels in the spectrum of NREM sleep “depth” or physiological intensity. |
| Sleep Stage REM | The stage of sleep with highest brain
activity characterized by enhanced brain metabolism and
vivid hallucinatory imagery or dreaming. There are spontaneous rapid eye movements, resting muscle activity is suppressed and awakening threshold to nonsignificant stimuli is
high. The EEG is a low-voltage, mixed-frequency, non-alpha
record. REM sleep is usually 20-25% of total sleep time. It
is also called “paradoxical sleep.” |
| Sleep Stages | Distinctive stages of sleep, best demonstrated
by polysomnographic recordings of the EEG, FOG, and EMG. |
| Sleep Stage 1 (NREM Stage 1) | A stage of NREM sleep
that occurs at sleep onset or that follows arousal from sleep
stages 2, 3, 4, or REM. It consists of a relatively low-voltage
EEG with mixed frequency, mainly theta activity and alpha
activity of less than 50% of the scoring epoch. It contains
EEG vertex waves and slow rolling eye movements; no sleep
spindles, K complexes, or REMs. Stage 1 normally represents
4-50% of the major sleep episode. |
| Sleep Stage 2 (NREM Stage 2) | A stage of NREM sleep
characterized by the presence of sleep spindles and K complexes present in a relatively low-voltage, mixed-frequency EEG background; high-voltage delta waves may comprise up to 20% of stage 2 epochs; usually accounts for 45-55% of the major sleep episode. |
| Sleep Stage 3 (NREM Stage 3) | A stage of NREM sleep
defined by at least 20% and not more than 50% of the episode
consisting of EEG waves less than 2 Hz and more than 75
uV (high-amplitude delta waves); a “delta” sleep stage; with
stage 4, it constitutes “deep” NREM sleep, so-called slow
wave sleep (SWS); often combined with stage 4 into NREM
sleep stage 3/4 because of the lack of documented physiological differences between the two; appears usually only in the first third of the sleep episode; usually comprises 4-6%
of total sleep time. |
| Sleep Stage 4 (NREM Stage 4) | All statements concerning
NREM sleep stage 3 apply to stage 4 except that high-voltage.
EEG slow waves persist 50% or more of the epoch; NREM
sleep stage 4 usually represents 12-15% of total sleep time.
Sleepwalking, sleep terrors, and confusional arousal episodes
generally start in stage 4 or during arousals from this stage.
See Sleep Stage 3. |
| Sleep Structure | Similar to sleep architecture. However, in
addition to encompassing sleep stages and sleep cycle relationships, sleep structure assesses the within-stage qualities of the EEG and other physiological attributes. |
| Sleep Talking | Talking in sleep that usually occurs in the
course of transitory arousals from NREM sleep. Can occur
during stage REM sleep, at which time it represents a motor
breakthrough of dream speech. Full consciousness is not
achieved and no memory of the event remains. |
| Sleep-Wake Cycle | Basically, the clock hour relationships
of the major sleep and wake episodes in the 24-hour cycle.
See Phase Transition; Circadian Rhythm. |
| Sleep-Wake Shift (-Change, -Reversal) | When sleep as a
whole or in part is moved to a time of customary waking
activity, and the latter is moved to the time of the major
sleep episode; common in jet lag and shift work. |
| Sleep-Wake Transition Disorder | A disorder that occurs
during the transition from wakefulness to sleep or from one
sleep stage to another. A form of the parasomnias; not a
dyssomnia. |
| Slow Wave Sleep (SWS) | Sleep characterized by EEG waves
of duration slower than 4 Hz. Synonymous with sleep stages
3 plus 4 combined. See Delta Sleep. |
| Snoring | A noise produced primarily with inspiratory respiration during sleep due to vibration of the soft palate and the pillars of the oropharyngeal inlet. All snorers have incomplete obstruction of the upper airway, and many habitual
snorers have complete episodes of upper airway obstruction. |
| Spindle REM Sleep> | A condition in which sleep spindles
persist atypically in REM sleep; seen in chronic insomnia
conditions and occasionally in the first REM period. |
| Synchronized | A chronobiological term used to indicate that
two or more rhythms recur with the same phase relationship.
In EEG it is used to indicate an increased amplitude and
usually a decreased frequency of the dominant activities. |
|
| Theta Activity | EEG activity with a frequency of 4-8 Hz,
generally maximal over the central and temporal cortex. |
| Total Recording Time (TRT) | The duration of time from
sleep onset to final awakening. In addition to total sleep time,
it is comprised of the time taken up by wake periods and
movement time until wake-up. See Sleep Efficiency. |
| Total Sleep Episode | This is the total time available for sleep
during an attempt to sleep. It comprises NREM and REM
sleep, as well as wakefulness. Synonymous and preferred to
the term total sleep period. |
| Total Sleep Time (TST) | The amount of actual sleep in a
sleep episode; equal to total sleep episode less awake time.
Total sleep time is the total of all REM and NREM sleep in
a sleep episode. |
| Trace Alternant | Define Here |
| Term Here | EEG pattern of sleeping newborns, characterized by bursts of slow waves, at times intermixed with sharp waves, and intervening periods of relative quiescence
with extreme low amplitude activity. |
| Tumescence (Penile) | Hardening and expansion of the penis(penile erection). When associated with REM sleep it is referred to as a sleep-related erection. |
| Twitch (Body Twitch) | A very small body movement such
as a local foot or finger jerk; not usually associated with
arousal. |
|
|
| Vertex Sharp Transient | Sharp negative potential, maximal
at the vertex, occurring spontaneously during sleep or
response to a sensory stimulus during sleep or wakefulness.
Amplitude varies but rarely exceeds 250 uV. Use of the term
vertex sharp wave is discouraged. |
|
| Wake Time | The total time scored as wakefulness in a polysomnogram occurring between sleep onset and final wake-up. |
| Waxing and Waning | A crescendo-decrescendo pattern of
activity, usually EEG activity. |
|
| Zeitgeber | An environmental time cue that usually heIps entrainment to the 24-hour day, such as sunlight, noise, social interaction, alarm clocks. |
| Top
|
|
|
|
|
© Copyright 2000-2005 Kestrel Sleep Diagnostics, Inc.
| |
