Chapter 9: Sleep, Dreaming, & Circadian Rhythms

Activation-synthesis hypothesis

Premise that states dreaming is just a way for the cortex to deal with the high activity of the brain stem & basal forebrain, serves a function in information processing & that dreams don't necessarily have meaning

Adenosine

A byproduct of energy used by neurons. As it builds, it causes drowsiness and promotes sleep

Alpha waves

Smooth electrical activity of 8-12 Hz & generally associated with a state of relaxation

Antihypnotics

Produce arousal and inhibit sleep (e.g. amphetamine & cocaine)

Basal forebrain

area anterior and dorsal to the hypothalamus; releases acetylcholine & is vital for REM sleep

Benzodiazepines

GABA agonists like valium that can be used as a sleep aid but can be addictive when combined with other drugs like alcohol & opiates, they can cause overdose by suppressing breathing

Beta waves

Irregular electrical activity of 12-38 Hz & generally associated with a state of arousal

Biofeedback

A technique in which a person uses a device to get real time info about physiological responses, and then uses associative learning to control actions typically out of our conscious control (e.g. heart rate, brain waves & temperature)

Caffeine

A competitive antagonist for adenosine that builds up while awake and the most common antihypnotic

Cataplexy

A sudden loss of voluntary muscle strength and control (atonia) that should only occur during REM but happens while awake

Central sleep apnea

Age related sleep disorder that causes breathing to stop for minutes at a time

Chronobiology

The study of how time affects biological changes in the body

Circadian rhythms

A consistent cycle of body activity & behavior that occurs over around 24 hours

Crepuscular

Awake & active during dawn & dusk but sleeping in the middle of the day & middle of the night (e.g. cats)

Delta waves

Regular synchronous electrical activity of 3 Hz or less & occurs during the deepest stages of slow-wave sleep

Diurnal

Awake & active during the day & sleeping at night (e.g. humans)

Electroencephalogram (EEG)

record of the electrical activity (waves) of the brain

Electrooculogram (EOG)

Measures eye movement

Free-running clock

Circadian rhythm without external cues - not always perfectly 24 hours

Glymphatic system

A lymphatic system made of tubal glial cells in the brain that participates in the removal of wastes and metabolites and distributing sugars & fats

Habenula

Connects the pineal gland to the thalamus & releases melatonin

Hypnotics

Sleeping aids or sleeping pills

Hypocretin

a neurotransmitter secreted by cells in the hypothalamus; helps regulate sleep-wake cycles, & prevents REM from occurring at the wrong time

Information processing theory of sleep

Theory that memories tend to improve during sleep as events are replayed, connections made that represent learning during the day are strengthened, & synapses & dendritic spines of memories that are not needed decrease

Insomnia

Recurring problems in falling or staying asleep that is usually associated with anxiety, depression, stress, eating, & traveling. It can also affect blood pressure, diabetes, weight, & heart disease

K complexes

High amplitude waves during N2

Locus coeruleus

Area in the dorsal pons that contains norepinephrine; primary role is arousal especially in stressful situations

Melanopsin

A photopigment in cells of the retina that are senstive to short wavelength (blue) light

Melatonin

A hormone manufactured by the pineal gland that produces sleepiness

Modafinil

Drugs like provigil prescribed to people with narcolepsy & causes hypocretin to be released

Narcolepsy

A sleep disorder characterized by uncontrollable sleep attacks. The sufferer may lapse directly into REM sleep, type 1: cataplexy, type 2: non-cataplexy. Potential hallucinations

Nocturnal

Awake & active during the night & sleeping during the day (e.g. bats)

Obstruction sleep apnea

disorder, most common in men, characterized by the back of the throat relaxing & blocking the airway

Parasomnias

Abnormal movements & behaviors while sleeping

Pineal gland

Communicates with the SCN, releases melatonin, & plays an important role in circadian rhythms & sleep/wake cycles

Ponto-geniculo-occipital (PGO) spikes

Term referring to dreaming generated by activity in the pontine reticular formation, the LGN, and the occipital lobe

Polysomnography

Multimodal technique to measure sleep disorders & physiological processes during sleep

Raphe nucleus

A group of nuclei located in the reticular formation of the medulla, pons, and midbrain, situated along the midline, contains serotonergic neurons responsible for sleep-wake cycles

REM rebound

increased amounts of REM sleep after being deprived of REM sleep on earlier nights

REM sleep

Stage of sleep associated with dreaming, high brain desynchronization, & happens in the later hours of the night & early morning.

REM sleep behavior disorder

A sleep disturbance in which atonia during REM sleep is not functioning correctly, resulting in the acting out of dreams

Sleep apnea

A sleep disorder characterized by temporary cessations of breathing during sleep and repeated momentary awakenings

Sleep paralysis

Inability to move before falling asleep or after waking up. Can produce hallucinations & atonia caused by REM happens too soon or doesn't dissipate after waking up.

Sleep spindles

short bursts of high frequency brain waves detected in stage 2 sleep

Suprachiasmatic nuclei (SCN)

Area in the hypothalamus just above the optic chiasm

Tau-mutant hamster

A research animal used to study circadian rhythms. It has a free-running clock of twenty to twenty-two hours.

Theta waves

Electrical activity of 3-8 Hz & occurs intermittently during early stages of slow-wave sleep

Unihemispheric sleep

A type of sleep in which one side of the brain is asleep while the other is conscious

Wearables

clothing or accessories that are equipped with computer technology or sensors that allow the collection and sharing of data

Z-drugs

GABA agonists, similar to benzodiazepines, like ambien that can cause sleep disturbances like sleep walking & eating

Zeitgebers

Environmental cues, such as time & temperature, that entrain circadian rhythms

Defensive activation theory

A theory by Eagleman and Vaughn (2021) that dreaming keeps neurons in the visual cortex in the occipital lobe active at night when our eyes are closed.

Ventrolateral preoptic nucleus of the hypothalamus (VLPO)

• Helps promote sleep

• GABA neurons

• Projects to locus coeruleus and raphe nucleus to inhibit arousal

• Also inhibits the lateral hypothalamus and neurotransmitter hypocretin