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
What waves feature during stage 3 of sleep?
Delta waves
True or False:
REMs can be seen during initial stage 1 EEG
False
REMs are experienced only during emergent stage 1 EEG
How long is each sleep cycle?
Around 90 minutes
True or False:
Antidepressants greatly reduced REM sleep without affecting aspects of dream recall
True
True or False:
Dreaming is unaffected by cortical lesions
False
Cortical lesions can abolish dreaming without affecting REM sleep
What is somniloquy?
Sleeptalking
What is somnambulism?
Sleepwalking
When does sleeptalking usually occur?
Usually during the transition to wakefulness but it can occur during any stage
When does sleepwalking occur?
Usually during slow-wave sleep (never during REM)
What did Freud believe dreams represented?
Dreams are triggered by unaccepted repressed wishes, often of a sexual nature
What are the two kinds of theories of sleep?
Recuperation theories
Adaption theories
What are the four main conclusions of the comparative analysis of sleep?
Sleep serves some important physiological function
The primary function of sleep is not some special, higher-order human function
Although sleep may be essential for survival, it is not necessarily needed in large quantities
There is no relationship between a species’ sleep time and its level of activity
What is a common confounder in sleep deprivation studies?
Stress
What are the three predictions that recuperation theories make about the effects of sleep deprivation?
Long periods of wakefulness will produce physiological and behavioural disturbances
These disturbances will grow worse as the sleep deprivation continues
After a period of deprivation has ended, much of the missed sleep will be regained
What are the effects of moderate sleep deprivation (loss of 3 to 4 hours) in humans?
Increased sleepiness
Decreased mood regulation
Decreased performance on tasks requiring attention
What types of cognitive function seem to be immune to sleep deprivation?
Logical deduction and critical thinking
What types of cognitive function seem to be susceptible to sleep deprivation?
Executive function
What are the physiological effects of sleep deprivation?
Reduced body temperature Increased blood pressure Decreased immunity Hormonal changes Metabolic changes
How many days of sleep deprivation are usually required before microsleeps occur?
2 to 3 days
What is a criticism of the carousel apparatus?
It may be that repeatedly being awakened by this apparatus kills the experimental rats not because it keeps them from sleeping but because it is stressful
What is REM rebound?
A phenomenon that occurs following a period of REM-sleep deprivation where an individual has more than their usually amount of REM sleep for the first two or three nights
What is the default theory of REM sleep?
It is difficult to stay continuously in NREM sleep, so the brain periodically switches to one of two other states. If there are any immediate bodily needs to be taken care of, the brain switches to wakefulness; if there are no immediate needs, it switches to REM sleep.
REM sleep is characterised by rapid eye movement, loss of core muscle tone, and _______
Emergent stage 1 EEG
________ believed that dreams are triggered by unaccepted repressed wishes
Sigmund Freud
Freud referred to dreams that we experience as _______
Manifest dreams
The _________ hypothesis states that the information supplied to the cortex during REM sleep is largely random, and the resulting dream is the cortex’s effort to make sense of random signals
Activation-synthesis
_______ are brief periods of sleep that are typically about two or three seconds long
Microsleeps
The effects of sleep deprivation are often difficult to study because they are often confounded by ______
Stress
Convincing evidence that REM-sleep deprivation does not produce severe memory problems comes from the study of patients taking certain _________ drugs
Antidepressant
After a lengthy period of sleep deprivation (e.g. several days), a person’s first night of sleep is only slightly longer than usual, but it contains a much higher proportion of ______ waves
Slow or delta
________ sleep in particular, rather than sleep in general, appears to play the major restorative role
Slow-wave (or stage 3)
Environmental cues, such as the light-dark cycle, that can entrain circadian rhythms are called _______
Zeitgebers
What are the symptoms caused by jet lag and shift work?
Sleep disturbances, fatigue, general malaise, and deficits on tests of physical and cognitive function
How can someone reduce the disruptive effects of jet lag?
Gradually shifting one’s sleep-wake cycle in the days prior to the flight
Administering treatments after the flight that promote the required shift in the circadian rhythm (i.e. melatonin)
Lesions to the suprachiasmatic nuclei results in what?
Disruption of various circadian cycles
True or False:
Under certain conditions, bilateral SCN lesion have been shown to leave some circadian rhythms unaffected while abolishing others
True
True or False:
Bilateral SCN lesions eliminate the ability of all environmental stimuli to entrain circadian rhythms
False
They do not eliminate it
What happens when you cut the optic nerve before the optic chiasm?
The light-dark cycle can no longer entrain circadian rhythms
What happens when you cut the optic nerve after the optic chiasm?
The light-dark cycle is still able to entrain circadian rhythms
What are retinohypothalamic tracts?
Nerves that leave the optic chiasm and project towards the SCN that mediate the ability of light to entrain circadian rhythms
True or False:
Rod and cones are not required for entrainment of circadian rhythms
True
What cells in the eye detect the light responsible for circadian rhythm entrainment?
Retinal ganglion cells
What photopigment do retinal ganglion cells have?
Melanopsin
What was the first circadian rhythm gene to be discovered?
Tau
Which parts of the brain promote sleep?
Anterior hypothalamus and adjacent basal forebrain
Which parts of the brain promote wakefulness?
Posterior hypothalamus and adjacent midbrain
What are the effects of a cerveau isole preparation?
Continuous slow-wave sleep
Low levels of activity in the reticular formation produce _______ and high levels produce ________
Sleep; wakefulness
Which part of the brain controls REM sleep?
A variety of nuclei scattered thoughout the caudal reticular formation. Each site is responsible for controlling one of the major indices of REM sleep
_________ means lasting about one day
Circadian
Free-running rhythms are those that occur in environments devoid of _______
Zeitgebers
The major circadian clock seems to be located in the _______ nuclei of the hypothalamus
Suprachiasmatic
The ______ tracts conduct information about light-dark cycles to the SCN
Retinohypothalamic
The first mammalian circadian gene to have its structure characterised was ________
Clock
Patients with damage to the _________ hypothalamus and adjacent basal forebrain often have difficulty sleeping
Anterior
Damage to the _________ hypothalamus and adjacent areas of the midbrain often cause excessive sleepiness
Posterior
The low-amplitude high-frequency EEG of wakefulness is said to be ________
Desynchronised
In Bremer’s classic study, cats with a _________ preparation displayed an EEG characteristic of continuous slow-wave sleep
Cerveau isole
The indices of REM sleep are controlled by a variety of nuclei located in the caudal ________
Reticular formation
What are drugs that increase sleep called?
Hypnotic drugs
What are the complications of benzodiazepines as a hypnotic drug?
Tolerance Withdrawal symptoms (insomnia) Normal sleep pattern disruption Following day drowsiness Reduction of life expectancy
What are three classes of hypnotic drugs?
Benzodiazepines
Imidazopyridines
5-hydroxytryptophan (5-HTP)
What are three classes of antihypnotic drugs?
Cocaine-derived stimulants
Amphetamine-derived stimulants
Tricyclic antidepressants
What are side-effects of antihypnotic drugs?
Loss of appetite, anxiety, tremor, addiction and disturbance of normal sleep patterns
Which part of the brain synthesises melatonin?
Pineal gland
Does exogenous (externally produced) melatonin improve sleep?
Exogenous melatonin has a slight, but statistically significant, soporific (sleep-promoting) effect
A substance that adjusts the timing of internal biological rhythms are called what?
Chronobiotic
What are the two complementary categories of sleep disorders?
Insomnia and hypersomnia
True or False:
Many cases of insomnia are caused by physicians
True
What are the two types of sleep apnea disorders?
Obstructive sleep apnea
Central sleep apnea
What is obstructive sleep apnea?
Sleep apnea caused by muscles spasms or atonia (lack of muscle tone) that block respiratory passages
What is central sleep apnea?
The failure of the CNS to stimulate respiration
What are the symptoms of narcolepsy?
Severe daytime sleepiness and repeated, brief daytime sleep episodes
Cataplexy
Sleep paralysiss
Hypnagogic hallucinations
What findings have suggested that narcolepsy is caused by an abnormality in the mechanisms that trigger REM sleep?
People with narcolepsy often go straight into REM sleep when they fall asleep
They experience dreamlike states and loss of muscle tone while awake
Which neuropeptide is responsible for narcolepsy?
Decreased orexin
Which part of the brain produces orexin?
Posterior hypothalamus
Individuals who experience REM sleep without core muscle atonia suffer from what?
REM-sleep behaviour disorder
Which part of the brain is responsible for core muscle atonia during REM sleep?
Nucleus magnocellularis
True or False:
There is no differences between individuals who sleep 6 hours or less and individuals who sleep 8 hours or more
True
Because REM sleep is similar to wakefulness in several respects, it makes sense that REM sleep circuits are controlled by a structure involved in maintaining wakefulness: Select one: a. the reticular activating system. b. the basal forebrain. c. the thalamus.
a. the reticular activating system.
Bilateral lesions of the \_\_\_\_\_\_\_\_\_\_ selectively disrupt circadian cycles. Select one: a. reticular activating system b. suprachiasmatic nuclei c. lateral hypothalamus d. lateral preoptic area
b. suprachiasmatic nuclei
During REM sleep, changes in autonomic nervous system activity suggest: Select one: a. neural inactivity. b. increased relaxation. c. unresponsiveness. d. arousal.
d. arousal.
Melatonin is synthesized from: Select one: a. GABA. b. glutamate. c. serotonin. d. dopamine.
c. serotonin.
Most selective sleep-deprivation studies have been studies of \_\_\_\_\_\_\_\_\_\_ deprivation. Select one: a. REM-sleep b. stage 3 sleep c. NREM-sleep d. stage 2 sleep
a. REM-sleep
Paradoxically, insomnia is often caused by: Select one: a. hypnotic drugs. b. anxiety. c. depression. d. Sleep deprivation.
a. hypnotic drugs.
REM sleep without the usual core muscle atonia is likely a consequence of damage to the: Select one: a. caudal hypothalamus. b. nucleus magnocellularis. c. subfornical organ.
b. nucleus magnocellularis.
Slow-wave sleep seems to play a particularly important Select one: a. physiological role. b. psychological role. c. circadian role. d. recuperative role.
d. recuperative role.
Theories postulating that sleep permits the body to recover from internal deficits produced by wakefulness are often referred to as: Select one: a. recuperation theories. b. free-running theories. c. circadian theories. d. adaptation theories.
a. recuperation theories.
Under normal living conditions, most people sleep during:
Select one:
a. the rising phase of the circadian body-temperature cycle.
b. body temperature homeostasis.
c. internal desynchronization.
d. the falling phase of the circadian body-temperature cycle.
d. the falling phase of the circadian body-temperature cycle.
