A-C | D-G | H-L
| M-Q | R-T | U-Z
- advanced sleep phase syndrome (ASPS)
- circadian rhythm disorder in which the main sleep period is advanced in relation
to the desired clocktime, that results in symptoms of compelling
evening sleepiness, an early sleep onset, and an awakening that
is earlier than desired. More here.
- drug that binds to and causes a functional effect identical in
quality and quantity to the endogenous ligand
- altitude insomnia
- insomnia that occurs when people go to higher altitudes. Usually
accompanied by headaches, loss of appetite, and fatigue. Twenty-five
percent of individuals who go from sea level to 2,000 meters will
have some symptoms. Also called Acute mountain sickness, Acosta's
disease, Alpine sickness, and hypobaropathy.
- complete or partial loss of sensation, usually caused by artificially
produced unconsciousness. More.
- drug the binds but causes no functional effect; blocks the action
of the natural ligand or agonist drug
- drugs which combat the effects of histamine. (Histamine is a
chemical released by certain cells of the body.) Used to reduce
nausea and sickness. Drowinsess is a detrimental side-effect when
used for these purposes, but this drowsiness is desired when the
drugs are used to treat insomnia. Antihistimines are the active
component in over-the-counter sleep aids.
- awakening from sleep. Sleep scientists sometimes use this term
to refer to a change from a deeper stage of non-REM sleep to a
- arousal disorder
- parasomnia disorder presumed to be due to an abnormal arousal
function. Classical arousal disorders: sleepwalking, sleep terrors
and confusional arousals.
- arousal threshold
- in scientific studies this is a parameter that measures how easily
a sleeping person is awakened.
- group of medicines called central nervous system (CNS) depressants.
First developed in the 1950's, these drugs tranquilize and sedate.
They work by slowing down the activity of the central nervous system.
They slow the messages going to and from the brain to the body,
including physical, mental and emotional responses. Also referred
to as "minor tranquillisers".
Benzodiazepines (ben-zoe-dye-AZ-e-peens) belong to the group
of medicines called central nervous system (CNS) depressants (medicines
that slow down the nervous system).
- biological clock
- a collection of cells that regulates an overt biological rhythm,
such as the sleep/wake cycle, or some other aspect of biological
timing, including reproductive cycles or hibernation. The biological
clock of interest to sleep scientists is the circadian clock.
- biphasic sleep
- a pattern in which the main sleep period at night is broken into two rough halves, with a waking period of an hour of more in between. More.
- brain waves
- the brain's spontaneous electrical activity studied by electroencephalography
- teeth grinding or jaw clenching during sleep. The term clenching means you tightly clamp your top and bottom teeth together, especially
the back teeth. More.
- sudden muscle weakness associated with narcolepsy. It is often
triggered by emotions such as anger, surprise, laughter, and exhilaration.
No loss of consciousness is involved – i.e. it is not a black
out or a faint, and, despite the phonetic similarity of ‘narcolepsy’
and ‘cataplexy’ with ‘epilepsy’, cataplexy is not epileptic
in nature. You are fully conscious, you just can't move.
- light therapy. Use of bright light to affect a change in sleep
patterns. Chronotherapy advocates claim it affects the same brain
chemicals that antidepressant drugs do, with the advantages of being
less expensive, working very soon, and having fewer side effects.
- exhibiting a periodicity of 24 hours. Terms originated by Franz Halberg in the 1950s.
- circadian disruption
- also called circadian disturbance, a departure of the body's circadian cycle from the environment or habit. Results in a change in the time of day during which sleepiness and wakefullness happen. Often caused by jet lag (rapid travel across time zones), or transitions into and out of daylight savings time, or between workweeks and weekends.
- circadian rhythm
- relating to or exhibiting approximately 24-hour periodicity, especially
related to fluctuation of behavioral and physiological functions,
including sleep waking.
- circadian rhythm sleep disorders
- Disorders that are related to the timing of sleep within the 24-hour
day. Some of these disorders are influenced by the timing of the
sleep period that is under the individual's control (e.g., shift
work or time zone change). Others in this group are disorders of
neurological mechanisms (e.g., irregular sleep-wake pattern and
advanced sleep phase
syndrome). These are one of the major classifications of sleep disorders.
- CPAP - Continuous Positive Airway Pressure
- a machine that helps a person who has apnea breathe more easily
during sleep by sending blowing air at a constant pressure.
CPAP patients wear a face mask connected to a pump
that forces air into the nasal passages at pressures high enough
to overcome obstructions in the airway and stimulate normal breathing.
More on CPAP machines.
- delayed sleep phase syndrome
- circadian-rhythm sleep disorder thought to result from the endogenous
being “stuck” at a later-than-normal phase, relative
to the desired sleep-wake schedule. The basic pathophysiology of
DSPS remains poorly understood.
- deep sleep
- refers to combined non-REM sleep stages 3 and 4 (under the old
definition of stages. Under the new classification, just stage 3)
- delayed sleep phase disorder
- disorder in which the major sleep episode is delayed by two or
more hours of the desired bedtime. This causes difficulty awakening
at the desired time. More.
- delta sleep
- stage of sleep in which EEG delta waves are prevalent or predominant
(sleep stages 3 and 4). Called "slow wave" sleep because brain activity
slows down dramatically from the "theta" rhythm of Stage 2 to a
much slower rhythm of 1 to 2 cycles per second called "delta" and
the height or amplitude of the waves increases dramatically.
- delta waves
- brain waves with a frequency of 1 to 3 hertz that emanate from
the forward portion of the brain during deep sleep. Normal amplitude is 75 microvolts
- in the context of sleep studies and disorder diagnosis, refers
to lack of alignment between external signals and the biological
clock. The cause of many circadian disorders.
- difficulties initiating and maintaining sleep (DIS/DMS)
- diagnostic sleep study
- monitoring of several physiological activities. Usually performed
to determine the absence or presence of a specific sleep disorder.
The sleep study can occur in a sleep disorders center or in a patient's
home with portable recording equipment.
- active or occurring during the daytime; repeating once each day.
- inhibitory neurotransmitter involved in voluntary movement and
- When the body is in a state of desynchronization. In sleep medicine, this refers most often to people with circadian disorders.
- a measurement of the electrical activity associated with brain
activity. First developed in the 1920s by Hans Berger.
- electromyogram (EMG)
- a measurement of the electrical activity associated with muscle
movements. Part of the polysomnogram.
- a measurement of the electrical activity associated with eye movements. Part of the polysomnogram.
- endocrine system
- the ductless glands in the body that secrete hormones.
- to reset or align with the biological clock.
- bed-wetting, also called nocturnal enuresis or nocturnal micturition or nocturnia
- in polysomnography, an epoch is a
- epworth sleepiness scale
- a scale indicating propensity to sleep during the day as perceived
by patients. From the subjective answers to eight questions. A sample
is at http://www.stanford.edu/~dement/epworth.html
- The scale was developed by researchers in Australia and is widely
used by sleep professionals around the world to measure sleep deprivation.
It has the benefits of being fast and simple.
- excessive daytime sleepiness (EDS)
- (also "excessive daytime somnolence") - subjective
report of difficulty in staying awake, accompanied by a ready entrance
into sleep when the individual is sedentary
- EDS suggests the presence of a sleep disorder and is different
from fatigue. Depression, anxiety, stress, and boredom are commonly
thought to cause excessive sleepiness, but in fact these conditions
cause fatigue and apathy.
- endogenous rhythms
- rhythms driven by an internal, self-sustaining biological clock
rather than by signals that are external to the organism (for example,
- exogenous rhythms
- rhythms that are directly regulated by an external influence,
such as an environmental cue. They are not generated internally
by the organism itself.
- feeling of tiredness, weariness or lack or energy usually associated
with lower performance (physical or mental). Fatigue is different
from drowsiness. In general, drowsiness is feeling the need or propensity to sleep,
while fatigue is a lack of energy and motivation. Drowsiness and
apathy (a feeling of indifference or not caring about what happens)
can be symptoms of fatigue. Fatigue often develops in response to
physical exertion, emotional stress, boredom, or lack of sleep.
- ford insomnia response to stress test
- Quick test that is used to identify people at risk for insomnia. Developed at the Henry Ford Hospital. Available on-line at http://www.henryford.com/body.cfm?id=47590
- free-running disorder
- a circadian disorder where the sleep cycle becomes disattached
from the normal patterns observed by most of society, such as the
rising and setting of the sun. Often afflicts blind people. More.
- GABA (Gamma-Aminobutyric Acid)
- an amino acid neurotransmitter (C4H9NO2) in the brain. Believed
to be involved in muscle relaxation, sleep, diminished emotional
reaction and sedation.
- a false and distorted perception of objects or events.
- the ability or tendency of an organism or cell to maintain internal
equilibrium by adjusting its internal processes. From the Greek
"to remain the same".
- homeostatic regulation of sleep
- refers to the neurobiological signals mediating the pressure or
urge to sleep.
- excessive sleep, characterized by recurrent episodes of unusual
daytime sleepiness or prolonged nighttime sleep. Different from
feeling tired due to lack of or interrupted sleep at night, persons
with hypersomnia are compelled to nap repeatedly during the day,
often at inappropriate times such as at work, during a meal, or
in conversation. These daytime naps usually provide no relief from
symptoms. The symptoms are typically treated, not the underlying
problem. Page on hypersomnia.
- hypnagogic hallucination
- a “greater-than-life-like” dream experience. Sometimes
associated with narcolepsy.
- hypnic jerk
- a startle reaction as a person falls asleep; muscle jerks like
an electric shock. Normal. Everyone experiences them. Also called
a sleep start or a hypnagogic jerk.
- a graphical summary of the electrical activities occurring during
a night's sleep. More.
- medications that cause sleep or partial loss of consciousness.
They include benzodiazepines and imidazopyridines.
- a class of peptide hormones that function as neurotrasmitters. Important in the sleep-wake cycle. Also called orexin.
- a general term for the fear of sleep. It isn’t
classified as a sleep disorder ;it’s more properly thought of as an
anxiety disorder. There are many phobias. Treatment is the same as
for other anxiety disorders. Cognitive behavioral therapy is
considered the best long-term solution, although it is expensive.
Doctors also prescribe benzodiazepines for anxiety disorders.
Hypnophobia may also refer to a fear of being hypnotized.
- class of drugs prescribed for insomnia. Often called nonbenzodiazepines,
although nonbenzodiazepines refers to a number of different classes
of drugs. Imidazopyridines include zolpidem (Ambien) and alpidem.
- infradian rhythm
- biolpgical rhythm with a period longer than a day. Often seen in menstruation, breeding, or tidal rhythms
- initial insomnia
- sleep-onset insomnia
- complaint describing difficulty in sleeping. People with insomnia
have one or more of the following:
- difficulty falling asleep
- waking up often during the night and having trouble going
back to sleep
- waking up too early in the morning
- unrefreshing sleep.
Insomnia can cause problems during the day, such as sleepiness,
fatigue, difficulty concentrating, and irritability. Page on insomnia.
- person with insomnia, especially chronic insomnia. The word was coined in 1908.
- jet lag
- describes a combination of symptoms induced by a major rapid
shift in environmental time during travel to a new time zone. Called
"jet" lag because of the often noticed after airplane flights. Fatigue,
irritability, dehydration, and a broken sleep pattern are common
symptoms of jet lag.
- typical voltage patterns seen on EEG in light sleep. Happen every couple of minutues during Stage 2 sleep.
- lark (morning lark)
- person who naturally wakes up early and goes to bed early. See page on chronotypes.
- sudden awakening in which the person feels as if he or she is suffocating and has a wheezing.
- light sleep
- term used in clincial practice to describe non-REM stage 1, and
sometimes, stage 2 sleep. People in light sleep drift in and out
of sleep and can be awakened easily. Eyes move very slowly and muscle
activity slows. People awakened from stage 1 sleep often remember
fragmented visual images rather than narrative dreams. Many also
experience sudden muscle contractions called hypnic myoclonia, often
preceded by a sensation of starting to fall.
- light therapy
- form of therapy where the person is exposed to bright light at
the appropriate time of day to effect the timing, duration and quality
of sleep. Also used in the treatment of Seasonal Affective Disorder.
- luteinizing hormone
- a glycoprotein secreted by the pituitary gland. It stimulates
the gonads to secrete sex steroids.
- a hormone secreted by the pineal gland that is derived from the
amino acid tryptophan, which helps synchronize biological clock
neurons in the suprachiasmatic nucleus.
- partial awakening from sleep. An episode where a sleeper partially
awakes, but is not aware of it
- period lasting up to a few seconds during which people appear
to be asleep in otherwise waking periods. Cause for concern for
people in critical jobs like truck drivers or pilots.
- middle insomnia
- waking up during the night and not being able to fall back asleep quickly. Another name for sleep maintenance insomnia
- multiple sleep latency test (MSLT)
- a common sleep test given at sleep labs in the diagnosis of sleep
disorders. The multiple sleep latency test records brain waves (via
EEG), heart rate (via EKG), muscle activity and eye movements. Often
given as a series of "nap tests".
- stage 1 of sleep (NREM Stage 1)
- stage 2 of sleep (NREM Stage 2)
- stage 3 of sleep (NREM Stage 3)
- short period of sleep at a time separate from the major sleep
period, especially during the day
- sleep disorder characterized by brief attacks of deep sleep,
and with symptoms including excessive sleepiness, cataplexy, sleep
paralysis, hypnogogic hallucinations, overwhelming daytime sleepiness
(even after adequate nighttime sleep), and an abnormal tendency
to pass directly from wakefulness into REM sleep. See page on narcolepsy.
- natural short sleeper
- Person who normally sleeps less than five hours a night with no adverse effects. See page on short sleepers.
- compounds with classical “endocrine” functions also affect the
brain in a fashion that is not dependent upon the presence of the
appropriate endocrine or physiological target organ
- a chemical produced by neurons that carries messages to other
- unpleasant and/or frightening dream. Unlike night terrors, nightmares
occur during REM sleep.
- night terrors
- also known as sleep terrors, or pavor nocturnus. Incomplete arousal
from slow wave sleep accompanied by a state of intense fear and
agitation. The person awakens in terror
with feelings of anxiety and fear but is unable to remember any
incident that might have provoked those feelings. In contrast, people
who wake up from nightmares often recall some of the dream.
- urination at night especially when excessive
- relating to or taking place at night.
- nocturnal sleep-related eating disorder
- eating while sleepwalking. Typically the person doesn't remember
eating when he or she wakes up.
- nocturnal enuresis
- Bedwetting. Urinating during sleep
- non-REM sleep - a normal part of sleep accounting for typically
75-80% of sleep time. Characterized by slower and larger brain waves
than in REM. By larger, we mean greater amplitude in the EEG output.
- one full cycle of night and day; often simply called a day or a 24-hour day.
- obstructive sleep apnea (OSA)
- a disorder in which breathing is frequently interrupted for brief
intervals during sleep, resulting in intermittent decreases in blood
oxygen levels and transient arousals from sleep, leading to poor
sleep quality and excessive daytime sleepiness. See page
- protein neurotransmitter or neuropeptide active in the sleep
cycle and in appetite. Peptide family comprised of two peptides,
orexin-A (hypocretin-1) and orexin-B (hypocretin-2). Subject of
substantial scientific research at this time. Deficiency is associated
- Oxford Sleep Resistance test. Designed as an objective vigilance
test. Similar to the MSLT but without EEG monitoring in the sleep
cycle and in appetite
- night owl
- person who naturally sleeps late and goes to bed late
- paradoxical sleep
- REM Sleep
- the light/dark or day/night cycle.
- the brainstem region critical for initiating REM sleep.
- disorders that intrude into the sleep process and create disruptive
sleep-related events. These behaviors and experiences occur usually
during sleep, and are most often infrequent and mild. They may happen
often enough or become so bothersome that medical attention is required.
See page of parasomnias.
- partial agonist
- drug that causes functional effect that, at a maximum, is only
a fraction of that of the endogenous ligand
- periodic limb movement disorder
- phase advance
- a shift earlier in time, for instance if someone starts going
to bed earlier and waking up earlier.
- phase delay
- a shift later in time, for instance if one's sleep cycle moves
ahead on the clock
- polysomnogram (PSG)
- continuous and simultaneous recording of physiological variables
during sleep, i.e., EEG (brain waves) electromyography (major muscle
activity), electrooculography (eye movement), EKG (heart activity),
respiratory air flow, respiratory excursion, lower limb movement,
and other electrophysiological variables. See polysomnograms.
- a test of sleep cycles and stages through the use of continuous
recordings of brain waves (EEG), electrical activity of muscles,
eye movement (electrooculogram), breathing rate, blood pressure,
blood oxygen saturation, and heart rhythm and direct observation
of the person during sleep. See page
- a condition related to obstructive sleep apnea in which a very
obese person does not breathe sufficient air during sleep or while
awake. Also called Pickwickian syndrome
- obstructive apnea
- apnea due to a mechanical obstruction, such as a very large uvula
or tongue in the back of the mouth, or a problem with the trachea.
- quiet sleep
- Non-REM sleep
- rebound insomnia
- sleep difficulties after discontinuing use of a hypnotic medication.
- REM latency
- period of time from sleep onset to the first appearance REM.
- REM motor atonia
- when the large skeletal muscles go limp during REM sleep.
- 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
- REM sleep behavior disorder (RBD)
- very rare disorder in which sleeper acts out dreams, often violently,
and has bodily movement. The body is usually paralyzed during REM
sleep. Patients often report an ongoing, hallucinatory REM dream
- rapid eye movement (REM) sleep
- deep sleep period with rapid eye movements. Normal part of sleep
cycle. Recurs cyclically several times during a normal period of
sleep. Characterized by increased neuronal activity of the forebrain
and midbrain, by depressed muscle tone. Most dreaming occurs in
this stage, which accounts for about 20% of sleep in adults.
- recurrent insomnia
- chronic insomnia.
- REM sleep rebound
- increase in REM sleep following unnatural reduction. Extension
of time in, and an increase in frequency and density of REM sleep
- restless legs syndrome (RLS)
- sleep disorder characterized by a deep creeping, or crawling
sensation in the legs even when the legs are not moving. There is
an almost irresistible urge to move the legs; the sensations are
relieved by movement. See RLS
- physiological tendency to remain constant
- seasonal affective disorder
- a form of depression caused by inadequate bright light affecting the biological clock during the late autumn and winter. Treatment often
involves the use of light therapy.
- chemicals (sometimes medicines) tending to calm, and reduce nervousness
or excitement and foster sleep. Many sleep medicines are sedatives.
Sometimes sedation is an undesired side effect of drugs given for
other purposes. Common sedatives include Antihistamines,
Z-drugs, and herbal sedatives.
- neurotransmitter involved in several important body functions
such as memory, emotions, moods, sleep and arousal.
- shift work sleep disorder
- disorder characterized by excessive sleepiness and caused by working hours that differ from the body's circadian cycle.
- the natural periodic suspension of consciousness during which
the powers of the body are restored, characterized by lessened consciousness
and slowed-down metabolism
- sleep apnea
- condition where the sleeper repeatedly stops breathing for 10
or more seconds during sleep. The Greek word "apnea" literally means
"without breath." There are three types of apnea: obstructive, central,
and mixed; of the three, obstructive is the most common. Can be
dangerous as people with sleep apnea sometimes stop breathing hundreds
of times during the night and often for a minute or longer.
- sleep architecture
- NREM/REM stages and cycles of sleep and time spent in each stage.
Also called sleep timing mechanism. One's sleep architecture changes
with age. Middle-aged and elderly people tend to spend less time
in deeper sleep than younger people.
- sleep cycle
- term used by scientists and sleep researchers to describe the
pattern of sleep stages, especially the NREM-REM cycle
- sleep debt
- physiological state that results from recurrent sleep deprivation
occurs over time. When an individual does not experience sufficient
restorative daily sleep required to maintain a sense of feeling
rested and refreshed.
- sleep deprivation
- acute or chronic lack of sufficient sleep.
- sleep disorders
- general term applied to a broad range of illnesses, including
dysfunctional sleep mechanisms, abnormalities in physiological functions
during sleep, abnormalities of the biological clock, and sleep disturbances
that are induced by factors extrinsic to the sleep process
- sleep disordered breathing
- general description for a group of disorders that produce pauses
in breath in the sleeper or that reduce the amount of air the person
is getting. Apnea is a common type.
- sleep efficiency
- percentage of time in bed spent sleeping
- sleep fragmentation
- sleep interruption due to frequent or sustained awakenings or
early morning awakenings
- sleep hygiene
- conditions and practices that promote continuous and effective
sleep. These include bedtime routines, regular bed and arise times.
And regularly getting enough sleep to avoid sleepiness during the
day. For some people, can also refer to limiting alcoholic and caffeinated
beverages prior to bedtime and using exercise, nutrition, and environmental
factors so that they enhance, not disturb, restful sleep
- sleep hyperhidrosis or sleep
- profuse sweating during sleep
- sleep inertia
- feelings of grogginess and/or sleepiness that persist longer
than 10 to 20 minutes after waking up. Symptoms include what goes
under the scientific term is transitory "hypovigilance" or low vigilance,
along with confusion, disorientation of behavior and impaired cognitive
and sensory-motor performance. Happens often when a person is aroused
from deep sleep in the first part of the night. More on sleep
- sleep latency
- the time between going to bed and sleep onset. Similarly, the
term "REM sleep latency" refers to the time between sleep onset
and the onset of the first episode of REM sleep. The term "sleep
efficiency" refers to the proportion of time in bed that is spent
sleeping. Also called "sleep onset latency".
- sleep maintenance
- the ability to remain asleep for a long period of time
- sleep manners
- See this page
- sleep paralysis
- temporary inability to talk or move when falling asleep or waking
- sleep talking
- utterence of speech or sounds during sleep without awareness of
the event. Takes place during stage REMS, representing a motor breakthrough
of dream speech, or in the course of transitory arousals from NREMS
and other stages. The person is not fully consciousness and retains
no memory of the talking. See somniloquy
- sleep spindle
- event in the brain that produces a 12 to 14 Hz spike in voltage on an EEG. Characteristic of Stage 2 sleep.
- somnolence, drowsiness - state where the subject finds it difficult
to maintain the wakeful state and falls asleep if not actively kept
aroused. Differs from simply a feeling of physical tiredness or
listlessness. Is sleepiness a state or a trait? That's a philosophical question.
- somnambulism. A sleep disorder where the person gets out of bed
and walks around during sleep. Typically occurs in the first third
of the night during deep NREM sleep (stages 3 and 4).
- slow wave sleep
- stages 3 and 4 sleep. Called because the EEG readings show slow waves. Deep sleep.
- talking while asleep
- sleep disorder
- fear of sleep, fear of falling asleep. An anxiety
- drowsiness, especially when the person seems on the verge of falling asleep.
- noise produced with inspiratory respiration during sleep owing
to vibration of the soft palate and the pillars of the oropharyngeal
inlet. Forty-five percent of normal adults snore at least occasionally,
and 25 percent are habitual snorers. Problem snoring is more frequent
in males and overweight persons, and it usually grows worse with
age. Problem snorers may develop obstructive sleep apnea.
- stage 1 sleep
- EEG readings show theta rhythms – (4-8 Hz). External observers see shallow eye movements
- stage 2 sleep
- EEG readings show frequencies in the (4-7 Hz range with slow waves (K complexes) and sleep
spindles (rapid at 14-16 Hz)
- stage 3 sleep
- also called slow-wave sleep or slow-wave activity. EEG readings show delta waves (0.5-4 Hz) with high
amplitude (>75 microvolt)
- Stanford Sleepiness Scale
- 7-point rating scale consisting of seven numbered statements describing
subjective levels of sleepiness/alertness. An example can be seen
- suprachiasmatic nucleus (SCN)
- the part of the brain (in the hypothalamus) that contains the
biological clock for the circadian cycle.
- terminal insomnia
- waking up too early
- a part of the brain consisting of two large ovoid structures at
the base of the cerebrum. It acts as a vital relay station between
the sensory nerves and the cerebral cortex.
- the process of regulating body temperature.
- thetha waves
- EEG waves with frequency of 4–7 Hz.
- ultradian rhythm
- A biological perodicity of less than 24 hours. Compared to a circadian rhythm (about a day) and an infradian rhythm (longer than a day).
- unihemispheric sleep
- a type of sleep in which one side of the brain is asleep while
the other is awake. This phenomenon is observed most notably in
birds (like those that make long, transoceanic flights) and aquatic
mammals (like dolphins and porpoises).
- uvulopalatopharyngoplasty (UPPP)
- an operation on the throat to treat severe snoring and sleep
apnea. Soft tissue on the back of the throat and soft palate (the
uvula) is removed. The tonsils and possibly other excess tissue
may also be removed, if present.
- wake state (stage 0)
- characterized by fast frequency EEG beta (>12 Hz) and alpha
rhythm (8-12 Hz) if eyes are closed
- white noise
- heterogeneous mixture of sound waves extending over a wide frequency
range that may be used to mask unwanted noise that may interfere
- worn out syndrome
- a somewhat outdated term. Refers to the feeling of fatige resulting from too much sleep or more sleep than normal. Related to sleep inertia.
- German for "time givers". External cues that affect
the Circadian cycle. Examples include sunlight, familiar morning
noises and sounds, and meals.
Books about sleep
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