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Definition
| A brain potential of 8–12 Hz that occurs during relaxed wakefulness. |
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| A ventral region in the forebrain that has been implicated in sleep and Alzheimer’s disease. |
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Definition
| Sudden loss of muscle tone, leading to collapse of the body without loss of consciousness. |
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Definition
| A pattern of behavioral, biochemical, or physiological fluctuation that has a 24-hour period. |
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Definition
| Occurring on a roughly annual basis. |
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Definition
| The slowest type of EEG wave, characteristic of stage 3 slow-wave sleep. |
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Definition
| Also called beta activity. A pattern of EEG activity comprising a mix of many different high frequencies with low amplitude. |
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Definition
| A complex of two proteins that have bound together. |
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Definition
| Active during the light periods of the daily cycle. |
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Definition
| The unique assortment of environmental opportunities and challenges to which each organism is adapted. |
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Term
| electro-oculography (EOG) |
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Definition
| The electrical recording of eye movements, useful in determining sleep stages. |
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Term
| electroencephalography (EEG) |
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Definition
| The recording and study of gross electrical activity of the brain recorded from large electrodes placed on the scalp. The abbreviation EEG may refer either to the process of encephalography or to its product, the encephalogram. |
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Definition
| The electrical recording of muscle activity. |
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Definition
| The process of synchronizing a biological rhythm to an environmental stimulus. |
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Definition
| Referring to a rhythm of behavior shown by an animal deprived of external cues about time of day. |
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Definition
| A drug that renders an individual unconscious. |
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Definition
| Also called orexins. Neuropeptides produced in the hypothalamus that are involved in switching between sleep states, in narcolepsy, and in the control of appetite. |
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Term
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Definition
| Referring to a rhythmic biological event whose period is longer than that of a circadian rhythm—that is, longer than a day. |
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Definition
| Sometimes referred to by the French term, encéphale isolé. An experimental preparation in which an animal’s brainstem has been separated from the spinal cord by a cut below the medulla. |
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Definition
| Sometimes referred to by the French term, cerveau isolé. An experimental preparation in which an animal’s nervous system has been cut in the upper midbrain, dividing the brain from the brainstem. |
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Definition
| A sharp negative EEG potential that is seen in stage 2 sleep. |
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Definition
| A photopigment found within particular retinal ganglion cells that project to the suprachiasmatic nucleus. |
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Definition
| A disorder that involves frequent, intense episodes of sleep, which last from 5 to 30 minutes and can occur anytime during the usual waking hours. |
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Definition
| A sudden arousal from stage 3 slow-wave sleep that is marked by intense fear and autonomic activation. |
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Term
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Definition
| A long, frightening dream that awakens the sleeper from REM sleep. |
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Definition
| Active during the dark periods of the daily cycle. |
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Definition
| The interval of time between two similar points of successive cycles, such as sunset to sunset. |
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Definition
| A shift in the activity of a biological rhythm, typically provided by a synchronizing environmental stimulus. |
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Term
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Definition
| A secretory gland in the brain midline; the source of melatonin release. |
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Term
| rapid-eye-movement (REM) sleep |
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Definition
| Also called paradoxical sleep. A stage of sleep characterized by small-amplitude, fast-EEG waves, no postural tension, and rapid eye movements. |
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Term
| REM behavior disorder (RBD) |
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Definition
| A sleep disorder in which a person physically acts out a dream. |
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Term
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Definition
| An extensive region of the brainstem (extending from the medulla through the thalamus) that is involved in arousal (waking) and motor control. |
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Term
| retinohypothalamic pathway |
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Definition
| The projection of retinal ganglion cells to the suprachiasmatic nuclei. |
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Definition
| A sleep disorder in which respiration slows or stops periodically, waking the patient. Excessive daytime somnolence results from the frequent nocturnal awakening. |
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Definition
| A period of slow-wave sleep followed by a period of REM sleep. In humans, a sleep cycle lasts 90–110 minutes. |
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Definition
| The partial or total prevention of sleep |
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Definition
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Definition
| A state during the transition to or from sleep, in which the ability to move or talk is temporarily lost. |
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Definition
| The process of sleeping more than is normal, after a period of sleep deprivation, as though in compensation. |
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Term
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Definition
| A characteristic 14- to 18-Hz wave in the EEG of a person in stage 2 sleep. |
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Term
| sleep state misperception |
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Definition
| Commonly, a person’s perception that he has not been asleep when in fact he was. Typically occurs at the start of a sleep episode. |
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Term
| sleep-maintenance insomnia |
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Definition
| Difficulty in staying asleep. |
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Term
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Definition
| Difficulty in falling sleep. |
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Term
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Definition
| Sleep, divided into stages 1–3, that is defined by the presence of slow-wave EEG activity. |
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Term
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Definition
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Term
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Definition
| The initial stage of slow-wave sleep, which is characterized by small-amplitude EEG waves of irregular frequency, slow heart rate, and reduced muscle tension. |
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Term
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Definition
| A stage of slow-wave sleep that is defined by bursts of regular 14- to 18-Hz EEG waves called sleep spindles. |
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Term
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Definition
| A stage of slow-wave sleep that is defined by the spindles seen in stage 2 sleep, that is defined by the presence of a large amplitude of slow waves (delta waves). |
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Term
| sudden infant death syndrome (SIDS) |
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Definition
| Also called crib death. The sudden, unexpected death of an apparently healthy human infant who simply stops breathing, usually during sleep. SIDS is not well understood. |
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Term
| suprachiasmatic nucleus (SCN) |
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Definition
| A small region of the hypothalamus above the optic chiasm that is the location of a circadian oscillator. |
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Term
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Definition
| A region of the basal hypothalamus, near the pituitary stalk, that plays a role in generating SWS. |
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Term
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Definition
| Referring to a rhythmic biological event whose period is shorter than that of a circadian rhythm, usually from several minutes to several hours long. |
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Term
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Definition
| An sharp-wave EEG pattern that is seen during stage 1 slow-wave sleep. |
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Term
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Definition
| Literally, “time-giver” (in German). The stimulus (usually the light-dark cycle) that entrains circadian rhythms. |
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