Sleep and Circadian Rhythms Flashcards
What is 5-hydroxytryptophan (5-HTP?
the precursor of serotonin
What is the activation-synthesis hypothesis?
the theory that the information supplied to the cortex by the brain stem during REM sleep is largely random and that the resulting dream is the cortex’s best effort to make sense of those random signals
What are the adaptation theories of sleep?
theories of sleep based on the premise that sleep evolved to protect organisms from predation and accidents and to conserve their energy rather than to fulfil some particular physiological need
What are alpha waves?
Regular, 8- to 12-per-second, high-amplitude EEG waves that typically occur during relaxed wakefulness and just before falling asleep
What are antihypnotic drugs?
sleep-reducing drugs
What are benzodiazepines?
a class of GABAa agonists with anxiolytic, sedative, and anticonvulsant properties; drugs such as chlordiazepoxide (Librium) and diazepam (Valium)
What is a carousel apparatus?
an apparatus used to study the effects of sleep deprivation in laboratory rats
What is cataplexy?
a disorder that is characterised by recurring losses of muscle tone during wakefulness and is often seen in cases of narcolepsy
What is cerveau isole preparation?
an experimental preparation in which the forebrain is disconnected from the rest of the brain by a midcollicular transection
What is a chronobiotic?
a substance that influences the timing of internal biological rhythms
What is a circadian clock?
an internal timing mechanism that is capable of maintaining daily cycles of physiological functions
What are circadian rhythms?
daily cycles of bodily functions
What are delta waves?
the largest and slowest EEG waves
What is a desychronised EEG?
low-amplitude, high-frequency EEG
What is an electroencephalogram (EEG)?
a measure of the gross electrical activity of the brain, commonly recorded through scalp electrodes
What is a electromyogram (EMG)?
a record of muscle tension
What is an electrooculogram (EOG)?
A measure of eye movement
What is emergent stage 1 EEG?
all periods of stage 1 sleep EEG except initial stage 1; each is associated with REMs
What is encephale isole preparation?
an experimental preparation in which the brain is separated from the rest of the nervous system by a transection of the caudal brain stem
What is executive function?
a collection of cognitive abilities (e.g., innovative thinking, lateral thinking and insightful thinking) that appear to depend on the prefrontal cortex
What is a free-running period?
the duration of one cycle of a free-running rhythm
What are free-running rhythms?
circadian rhythms that do not depend on environmental cues to keep them on a regular schedule
What is hypersomnia?
disorders characterised by excessive sleep or sleepiness
What are hypnagogic hallucinations?
dreamlike experiences that occur during wakefulness
What are hypnotic drugs?
sleep-promoting drugs
What does iatrogenic mean?
physician-created
What are imidazipyridines?
a class of GABAa agonists that were marketed for the treatment of insomnia
What is initial stage 1 EEG?
the period of the stage 1 EEG that occurs at the onset of sleep; it is not associated with REMs
What is insomnia?
Sleeplessness
What is internal desynchronisation?
the cycling on different schedules of the free-running circadian rhythms of two or more different processes
What is jet lag?
the adverse effects on bodily function of the acceleration of zeitgebers during eastbound flights or their deceleration during westbound flights
What is melanopsin?
photopigment found in certain retinal ganglion cells that responds to changes in background illumination and plays a role in the entrainment of circadian rhythms
What is melatonin?
a hormone that is synthesised from serotonin in the pineal gland, and is both a soporific and a chronobiotic
What are microsleeps?
brief periods of sleep that occur in sleep-deprived subjects while they remain sitting or standing
What are monophasic sleep cycles?
sleep cycles that regularly involve only one period of sleep per day, typically at night
What is narcolepsy?
a disorder of hypersomnia that is characterised by repeated, brief daytime sleep attacks and cataplexy
What is the nucleus magnocellularis?
the nucleus of the caudal reticular formation that promotes relaxation of the core muscles during REM sleep and during attacks of cataplexy
What is orexin?
a neuropeptide that has been implicated in narcolepsy; sometimes called hypocretin
What is periodic limb movement disorder?
characterised by periodic, involuntary movements of the limbs often involving twitches of the legs during sleep; one cause of insomnia
What is the pineal gland?
the endocrine gland that is the human body’s sole source of melatonin
What are polyphasic sleep cycles?
sleep cycles that regularly involve more than one period of sleep per day
What are recuperation theories of sleep?
theories based on the premise that being awake disturbs the body’s homeostasis and the function of sleep is to restore it
What is REM sleep?
the stage of sleep characterised by rapid eye movement, loss of core muscle tone and emergent stage 1 EEG
What is REM-sleep behaviour disorder?
a disorder where the individual experiences REM sleep without core-muscle atonia
What is restless legs syndrome?
tension of uneasiness in the legs that keeps a person from falling asleep; one cause of insominia
What is the reticular activating system?
the hypothetical arousal system in the reticular formation
What is sleep apnea?
a condition in which sleep is repeatedly disturbed by momentary interruptions in breathing
What is sleep inertia?
the unpleasant feeling of grogginess that is sometimes experienced for a few minutes after waking
What is sleep paralysis?
a sleep disorder characterised by the inability to move (paralysis) just as a person is falling asleep or waking up
What is slow-wave sleep (SWS)?
stage 3 sleep, which is characterised by the largest and slowest EEG waves (delta waves)
What is the suprachiasmatic nuclei (SCN)?
nuclei of the medial hypothalamus that control the circadian cycles of various body functions
What is tau?
the first circadian gene to be identified in mammals
What are zeitgebers?
environmental cues, such as light-dark cycle, that entrain circadian rhythms
What are the three standard psychophysiological measures of sleep?
EEG
EOG
EMG
According to the American Academy of Sleep Medicine, how many stages of sleep are there?
Three
What are the characteristics of brain waves during stage 1 of sleep?
Low-voltage, high-frequency signals that is similar to, but slower than, that of alert wakefulness
What are the characteristics of brain waves during stage 2 of sleep?
Higher-amplitude and lower-frequency signals compared to stage 1.
K complexes and sleep spindles also feature
A single large negative wave followed immediately by a single large positive wave experienced during stage 2 is called what?
A K complex
A 0.5 - 3-second waxing and waning burst of 9- to 15-Hx waves experienced during stage 2 is called what?
A sleep spindle