14 - Sleep, Dreaming, and Circadian Rhythms

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rapid eye movement (REM)

was discovered to occur under the closed eyelids of sleepers during periods of low-voltage, fast EEG activity

electroencephalogram (EEG), electrooculogram (EOG), and neck electromyogram (EMG)

three standard psychophysiological bases for defining the stage of sleep

first-night phenomenon

the disturbance of sleep observed during the first night in a sleep laboratory

alpha waves

After the eyes are shut and a person prepares to go to sleep, _____ waves—waxing and waning bursts of 8 to 12Hz EEG waves—begin to punctuate the low-voltage, high-frequency waves of alert wakefulness

stage 1 sleep EEG

low-voltage, high frequency 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 than the stage 1 EEG; in addition, it is punctuated by two characteristic wave forms: K complexes and sleep spindles

K complex

a single large negative wave (upward deflection) followed by a single large positive wave (downward deflection)

sleep spindle

Each _______ is a 0.5-3 second waxing and waning burst of 9-15Hz waves

stage 3 sleep EEG

defined by a predominance of delta waves

delta waves

the largest and slowest EEG waves, with a frequency of 1-2Hz

REM sleep: NREM sleep

The sleep associated with emergent stage 1 EEG is often called _____, 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

sleeptalking

somniloquy

sleepwalking

somnambulism

activation-synthesis

The essence of the ___________ hypothesis 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

The essence of _____________ is that being awake disrupts the homeostasis of the body in some way and sleep is required to restore it.

adaptation theories of sleep

The essence of _____________ is that sleep is not a reaction to the disruptive effects of being awake but the result of an internal 24-hour timing mechanism (we humans are programmed to sleep at night regardless of what happens to us during the day)

Adaptation

________ theories suggest that sleep is like reproductive behavior in the sense that we are highly motivated to engage in it, but we don’t need it to stay healthy.

microsleeps

brief periods of sleep, typically about 2 or 3 seconds long

carousel apparatus

used to deprive rats of sleep

zeitgebers

Environmental cues, such as the light–dark cycle, that can entrain (control the timing of) circadian rhythms are called ________

free-running rhythms; free-running period

Circadian rhythms in constant environments are said to be _________, and their duration is called the __________

internal desynchronization

when subjects are housed in constant laboratory environments, their sleep–wake and body temperature cycles sometimes break away from one another

jet lag

occurs when the zeitgebers that control the phases of various circadian rhythms are accelerated during east-bound/west-bound flights (phase advances/delays respectively)

shift work

In ______ , the zeitgebers stay the same, but workers are forced to adjust their natural sleep–wake cycles in order to meet the demands of changing work schedules

circadian clock

The fact that circadian sleep–wake cycles persist in the absence of temporal cues from the environment indicates that the physiological systems that regulate sleep are controlled by an internal timing mechanism—the ____

tau

the mutated gene in a group of hamsters that caused an abnormally short 20-hour free-running circadian rhythm

cerveau isolé preparation

translates to isolated forebrain, between their inferior colliculi and superior colliculi in order to disconnect their forebrains from ascending sensory input

disrupts the normal cycle of sleep EEG and wakefulness EEG (continuous slow-wave sleep)

encéphale isolé preparation

transections located in the caudal brain stem, thus, disconnecting the brain from the rest of the nervous system.

does not disrupt the normal cycle of sleep EEG and wakefulness EEG

hypnotic drugs

drugs that increase sleep

antihypnotic drugs

drugs that reduce sleep

5-HTP

the precursor to serotonin because it can readily pass through the blood-brain barrier

melatonin

A third class of sleep-influencing drugs comprises those that influence its circadian rhythmicity; the main drug of this class

soporific

sleep promoting drugs

chronobiotic

melatonin is better classified as a ____ (a substance that adjusts the timing of internal biological rhythms) than a soporific

benzodiazepines

Originally for anxiety but commonly prescribed for sleep problems

Insomnia

Difficulty initiating or maintaining sleep. It includes a range of issues, from taking too long to fall asleep to waking frequently or too early

Hypersomnia

Disorders involving excessive sleep or daytime sleepiness

Obstructive Sleep Apnea

Caused by blocked airways due to atonia or muscle spasms; common in snorer

Central Sleep Apnea

Caused by the brain failing to send proper signals to muscles controlling breathing.

Periodic Limb Movement Disorder

Involuntary limb movements during sleep, often unnoticed by the person but disrupting sleep quality.

Restless Legs Syndrome

An urge to move the legs due to discomfort, especially when lying down, making it hard to fall asleep.

Hypnagogic hallucinations

dreamlike experiences during wakefulness

REM Sleep Behavior Disorder (RBD)

A disorder where individuals physically act out dreams due to the absence of typical REM sleep muscle atonia. Common in Parkinson’s disease patients.

REM Sleep Abnormality in Narcolepsy

Narcoleptics often enter REM sleep directly and experience REM features (e.g., paralysis, vivid dreams) while awake.

sleep inertia

feeling groggy from too much sleep

polyphasic sleep cycles

sleep cycle of regularly sleeping more than once per day

monophasic sleep cycles

sleep once per day