13-Sleep, Dreaming, and Circadian Rhythms

Rapid eye movement (REM)

occur under the closed eyelids of sleepers

during these periods of low-voltage, fast EEG activity

1. electroencephalogram (EEG)

2. electrooculogram (EOG)

3. neck electromyogram (EMG)

became the three standard

psychophysiological bases for defining

the stages of sleep

first-night phenomenon

The disturbance of sleep observed during

the first night in a sleep laboratory

is called the

Alpha waves

waxing and waning bursts of 8- to

12-Hz EEG waves—begin to punctuate the low-voltage high-frequency waves of alert wakefulness

Stage 1 sleep EEG

as the person falls

asleep, there is a sudden transition to a

period of

Stage 1 sleep EEG

is a low-voltage, highfrequency

signal that is similar to, but

slower than, that of alert wakefulness.

Stage 2 sleep EEG

has a slightly higher amplitude and a lower

frequency

K complex

is a single large negative

wave (upward deflection) followed immediately by a single

large positive wave (downward deflection)

Sleep spindle

is a 0.5- to

3-second waxing and waning burst of 9- to 15-Hz waves

Stage 3 sleep EEG

is defined by a predominance of delta waves

Delta waves

the largest

and slowest EEG waves, with a frequency of 1 to 2 Hz.

initial stage 1 EEG

The first period of stage 1 EEG during

a night’s sleep is not marked by

any striking electromyographic or electrooculographic

changes

emergent stage 1 EEG

are accompanied by REMs

and by a loss of tone in the muscles of the body core.

REM sleep

The sleep associated with emergent stage 1 EEG

is often called -

NREM sleep

after the

associated rapid eye movements; whereas all other stages

of sleep together are called

slow-wave sleep (SWS)

NREM 3 is often referred to as - after the delta waves that characterize it

Somniloquy

sleeptalking

Somnambulism

sleepwalking

Sigmund Freud

believed that dreams are triggered by unacceptable repressed

wishes, often of a sexual nature.

Manifest dream

dreams we experience

Latent dreams

real dreams

activation-synthesis hypothesis

The essence of the - is that the information supplied to the cortex

during REM sleep is largely random and that the resulting

dream is the cortex’s effort to make sense of these random

signals.

recuperation theories of sleep

being awake disrupts the homeostasis (internal physiological

stability) of the body in some way and sleep is required

to restore it.

recuperation theories of sleep

they all imply that sleepiness is triggered by

a deviation from homeostasis caused by wakefulness and

that sleep is terminated by a return to homeostasis.

adaptation theories of sleep

is that sleep

is not a reaction to the disruptive effects of being awake but the result of an internal 24-hour timing mechanism

adaptation theories of sleep

focus more on when we sleep than on the function

of sleep

mammals and birds

the sleep of -,

like ours, is characterized by high-amplitude, low-frequency

EEG waves punctuated by periods of low-amplitude, highfrequency

waves

executive function

(cognitive abilities that appear

to depend on the prefrontal cortex

Microsleeps

are brief periods

of sleep, typically about 2 or 3 seconds long, during which

the eyelids droop and the volunteers become less responsive

to external stimuli, even though they remain sitting

or standing

carousel apparatus

has been used to

deprive rats of sleep

REM rebound

First, following REMsleep

deprivation, participants display a -; that

is, they have more than their usual amount of REM sleep

for the first two or three nights

default theory of REM Sleep

According to this

theory, it is difficult to stay continuously in NREM

sleep, so the brain periodically switches to one of

two other states.

circadian rhythms

Most surface-dwelling

species have adapted to this regular change in their environment

with a variety of

nocturnal animals

such as rats, sleep for much of the

day and stay awake at night

zeitgebers

Environmental cues, such as the light–dark cycle,

that can entrain circadian rhythms are called

free-running rhythms

Circadian rhythms in constant environments

are said to be

free-running period

vary in length from individual to individual, are of

relatively constant duration within a given individual, and

are usually longer than 24 hours

internal desynchronization

when subjects are housed in constant

laboratory environments, their sleep–wake and body temperature

cycles sometimes break away from one another

Jetlag

occurs when the zeitgebers

that control the phases of various circadian rhythms are

accelerated during east-bound flights or decelerated during west-bound flights

phase advance

east-bound flights

phase delays

west-bound flights

Circadian clock

the physiological systems that regulate sleep are controlled

by an internal timing mechanism

suprachiasmatic nuclei (SCN)

specific lesions of the - of the medial hypothalamus

were shown to disrupt various circadian cycles, including

sleep–wake cycle

retinohypothalamic tracts

which leave the optic chiasm and project to the adjacent

suprachiasmatic nuclei

retinohypothalamic tracts

mediate the ability of light to entrain circadian rhythms

melanopsin

During the course of evolution, these photoreceptors

have sacrificed the ability to respond quickly and

briefly to rapid changes of light in favor of the ability to

respond consistently to slowly changing levels of background

illumination. Their photopigment is

tau

breeding experiments showed that the abnormality was the

result of a genetic mutation, and the gene that was mutated

was named

clock

first to have its molecular structure characterized.

Baron Constantin von Economo

discovered that the brains of deceased victims who had

problems with excessive sleep all had damage in the posterior

hypothalamus and adjacent parts of the midbrain

posterior hypothalamus

promotes wakefulness

anterior hypothalamus

promotes sleep

cerveau isolé preparation

severed the brain

stems of cats between their inferior colliculi

and superior colliculi in order to disconnect

their forebrains from ascending sensory input

desynchronized EEG

low-amplitude, high-frequency EEG.

encéphale isolé preparation

These transections were located in the

caudal brain stem, and thus, they disconnected the

brain from the rest of the nervous syste

reticular formation

wakefulness structure in

the brain stem was the

reticular activating system,

proposed that low levels of

activity in the reticular formation produce

sleep and that high levels produce wakefulnes

caudal reticular formation

The fourth area of the brain involved in sleep controls

REM sleep

Hypnotic drugs

drugs that increase sleep

Antihypnotic drugs

drugs that reduce sleep

melatonin

sleep-influencing drugs

comprises those that influence its circadian rhythmicity

1. Benzodiazepines

2. Imidazopyridines

3. 5- hydroxytryptophan (5-HTP)

classes of hypnotic drugs

benzodiazepines

are GABA agonists, were developed and tested for the treatment

of anxiety, yet they are some of the most commonly

prescribed hypnotic medications

Diazepam and clonazepam

examples of benzodiazepines

Imidazopyridines

GABAA agonists marketed for the treatment

of insomnia. It was claimed that they have fewer adverse

side effects and less potential for addiction

Zolpidem

One of the

most widely prescribed imidazopyridines is

5- hydroxytryptophan (5-HTP)

the precursor of serotonin—

because it but not serotonin, readily passes

through the blood–brain barrier.

1. Cocaine-derived stimulant

2. Amphetamine-derived stimulants

3. Tricyclic antidepressants

classes of antihypnotic drugs

Antihypnotic drugs

The drugs in these three

classes seem to promote wakefulness by

boosting the activity of catecholamines by

increasing their release into synapses, by blocking

their reuptake from synapses, or both.

Pineal gland

Melatonin is a hormone synthesized from the neurotransmitter

serotonin in the -

Pineal gland

is an inconspicuous gland that

René Descartes once believed to be the seat of the soul.

Chronobiotic

a substance that adjusts the timing of internal

biological rhythms

Insomnia

includes

all disorders of initiating and maintaining

sleep

Hypersomnia

includes disorders of

excessive sleep or sleepiness

Iatrogenic

Many cases of insomnia are -, or physician-created

sleep latency

time to fall asleep)

sleep apnea

stops breathing

many times each night

Obstructive sleep apnea

results from obstruction

of the respiratory passages by muscle spasms or

atonia

central sleep apnea

results

from the failure of the central nervous system to stimulate

respiration

Periodic limb movement disorder

characterized by periodic, involuntary movements of the

limbs, often involving twitches of the legs during sleep.

Restless leg syndrome

They

complain of a hard-to-describe tension or uneasiness in

their legs that keeps them from falling asleep

Sleep restriction therapy

One of the most effective treatments for insomnia is

Narcolepsy

is the most widely studied disorder of hypersomnia

Narcolepsy

experience

severe daytime sleepiness and repeated, brief (10- to

15-minute) daytime sleep episod

Cataplexy

is characterized

by recurring losses of muscle tone during wakefulness,

often triggered by an emotional experience

Sleep paralysis

is the inability to move just as one is falling asleep

or waking up.

Hypnagogic hallucinations

are dreamlike

experiences during wakefulness

Orexin/ hypocretin

The gene that causes narcolepsy encodes a receptor

protein that binds to a neuropeptide called

REM-sleep–related disorders

Several sleep disorders are specific to REM sleep

REM-sleep behavior disorder

Some patients experience REM sleep without core muscle

atonia and is common

in individuals with Parkinson’s disease

nucleus magnocellularis

structure of the caudal reticular formation that evolved to control muscle relaxation during REM sleep

polyphasic sleep cycles

Most mammals and human infants display -, they regularly sleep more than once per day

Monophasic sleep cycles

most adult humans display -, they sleep once per day

Sleep inertia

too much sleep which

left them groggy for several minutes when they awoke